An overview of the development of teenagers with Down syndrome (11-16 years)

doi:10.3104/9781903806043


Health care for teenagers with Down syndrome

Teenagers with Down syndrome, like typically developing teenagers, may be affected by any type of illness. However, it is recommended that all teenagers and adults with Down syndrome have regular health checks to detect certain disorders as soon as possible. These systematic health checks should be carried out because people with Down syndrome tend to be affected by a number of disorders more commonly than other people.

Some of the health issues which are of particular importance for teenagers with Down syndrome are the same as those for younger children (hearing, vision, thyroid, sleep apnoeas, atlanto-axial instability), others seem to fall in incidence (behavioural sleep difficulties, infections) and there are some new concerns for this age group (dental issues, puberty and sexual health, obesity and mental health).

In the authors' recent survey of 46 teenagers aged 11 to 20 years, 14 (30%) were on regular medications, 7 for thyroid, 3 for asthma, 1 for possible epilepsy manifested as unusual aggressive outbursts, 1 for depression, 1 for colitis and 1 for overactivity.[1,2]

Other medical problems reported were 2 cases of kidney/bladder problems, 2 cases of scoliosis of the spine, 1 case of Perthes disease, 1 of leukaemia but now in remission, 1 of 'slight' atlanto-axial instability, 1 case of sleep apnoea, 1 case of eye infections, 1 case of persistent constipation, 2 cases of problems with teeth and 1 of 'scaly' scalp. Hearing losses were reported for 18 (39%) of the teenagers and 39 (85%) had visual defects, with 34 wearing glasses. Parents considered that 22 (48%) of the teenagers were overweight. Two of the 5 most developmentally delayed teenagers were described as autistic.

Of those disorders which have a higher prevalence in people with Down syndrome there are several which are of particular importance because they are relatively easy to diagnose and treat, because they are preventable or because they may have a high popular profile. These disorders and the health issues relevant to adolescence are included in this section.

These disorders and issues are as follows:-

  • Disorders of hearing
  • Disorders of vision
  • Infections
  • Disorders of thyroid function
  • Constipation and diarrhoea
  • Congenital disorders of the heart
  • Atlanto-axial instability
  • Sleep disturbances and sleep apnoea
  • Obesity and healthy eating
  • Dental care
  • Puberty and sexual health
  • Mental health

These disorders and their treatments are explained in this health section.

Hearing disorders

Children with Down syndrome tend to have a significantly higher incidence of hearing problems than other groups and almost all surveys conclude that about 80% of them will have some problem with hearing.[32] Studies of teenagers suggest that the incidence is lower (50-60%) but this is still a much higher incidence than would be found in the general population. One Canadian study reported that in a group of 34 teenagers with Down syndrome, 20 (59%) of the teenagers had hearing loss in at least one ear and 41% had losses in both ears.[33] Of the teenagers with hearing loss, 6 had wax blocking the ear canal and causing deafness, identifying the need for good hygiene and regular checking for dry wax. Ten of the teenagers had sensori-neural loss, 5 had conductive loss and 5 had both types of loss.

A study from the USA[34] reports similar figures for 18-20 year olds with Down syndrome, with some 48% with no hearing loss, some 13% had conductive losses, 13% sensorineural and 26% mixed losses. Some 40% of the teenagers had abnormal tympanograms, due to the long-term damaging effect of 'glue ear' in infants and young children. The incidence of hearing loss in this group of young adults with Down syndrome was much greater than in a comparison group of young adults with learning disabilities but not Down syndrome, 80% of whom had normal hearing. In this study, individuals with hearing losses performed less well on speech and language tasks and speech discrimination tasks.

In the authors' recent survey of 46 teenagers in the UK, 18 (39%) were reported to have hearing loss, 7 having moderate to severe losses and 11 having mild losses. Seven teenagers were using binaural (two) hearing aids. The teenagers with hearing losses were all having regular checks, with all having had a test within the previous 18 months and most having annual checks. Of the 28 reported to have no hearing loss, 23 could not report the last time they had had a hearing assessment. As other studies indicate a 50% incidence of hearing loss at this age, it is likely that some 4 or 5 teenagers in this study had undetected hearing loss. Of the 22 teenagers receiving regular hearing assessments, 4 were being seen at their schools and the rest at a hospital clinic.

There is some evidence of sensori-neural hearing losses increasing with age for individuals with Down syndrome and therefore it is important to continue with hearing checks at least every 3 years. (Some readers may be interested to note that in a similar survey in 1987, 80% of parents could not remember when their son or daughter had last had a hearing test and only 12% of the group were known to have hearing losses suggesting that many of those young people had undetected losses. Clearly, audiological care in the UK has improved significantly).

The importance of hearing cannot be overemphasised. The vast majority of teenagers with Down syndrome are still acquiring language and good hearing is involved in the continued development of speech and language as well as in socialisation. These, as well as other factors, have a profound effect upon the general intellectual development of the young person. The detection and continued treatment of hearing difficulties will be of great benefit to the teenager with Down syndrome.

Hearing and the function of the ear

Sounds, which are pressure waves in the air, travel along the external auditory canal and impinge upon the eardrum. This causes the eardrum to vibrate which, in turn, produces movements in the bones or ossicles in the middle ear. These movements produce vibrations upon the oval window (a small membrane separating the middle ear from the inner ear) and, via the fluid in the inner ear, stimulate the hair cells of the cochlea differentially, depending upon their various frequencies and pressures. It is at this stage that the information that is contained in these pressure changes is transformed (transduced) into nerve impulses which travel along the acoustic nerve via complex routes to the brainstem and brain where sound is perceived. Anything which interferes with any stage of this transfer chain will affect hearing.

The detection and diagnosis of hearing problems depends largely upon two factors:-

  1. the routine screening of all young children as part of the prevailing public health program
  2. the existence of a high level of suspicion on the part of carers that a hearing problem might be present.

Because of the high incidence of hearing problems in children with Down syndrome, and the fact that special testing techniques are sometimes needed, it is recommended that all of them should undergo appropriate hearing tests in a properly equipped and staffed audiology centre. The choice of which tests to use will depend upon circumstances and expert advice should be sought about this. The following descriptions are only a very short introduction to the subject.

The structure of the ear

Figure 8. The structure of the ear (diagram - not to scale)

Tympanometry (or impedance or compliance testing) is a commonly used test that records the manner in which the ear drum moves under test conditions and this provides information about the function of the middle ear. It is a painless test but it does require a degree of co-operation from the child.

In the UK it is Government policy for all children to have their hearing evaluated shortly after birth with the Oto Acoustic Emission Test (OAE). This test is purely passive in that it does not require any active participation from the child and is, therefore, suitable for very young children. There are several versions of this test but they are all based on the detection and analysis of certain sounds which are produced by the inner ear. OAE is mainly useful for the detection of sensori-neural deafness, and other passive tests, which measure the way in which the eardrum moves, are used to detect middle ear problems.

Visual Response Audiometry, VRA, is now being used for older children. This test is one of a group of behaviourall tests in which the child is conditioned to respond to sounds and is, therefore, useful for children who cannot be relied on to actively cooperate in responding to different types of sounds.

Where children are able to understand instructions to respond when they hear a sound, pure tone audiometry may be used. There are a number of versions of this technique, the principle of which is to test hearing by producing tones of known loudness and pitch in small increments. The child signals whenever he hears a specific tone and the responses are plotted on a chart - the audiogram.

The audiogram covers the range of frequencies (pitch) from 125 to 8000 Hz (cycles per second), and the range of loudness from zero to 100 dB (decibels).

The decibel is the standard unit of measurement for the intensity of sound, and is recorded on a logarithmic scale on the audiogram, separately for each ear.

A person with normal hearing will have a line from the lowest frequency tested, 125 Hz (cycles per second), to the highest frequency tested, 8000 Hz, at the level of about zero decibels (see Figure 9).

Normal right ear audiogram

Figure 9. Normal right ear audiogram

Figure 10 shows the audiogram from one ear of a person with a conductive hearing loss of about 35 dB.

Conductive hearing loss

Figure 10. Conductive hearing loss

The common causes of hearing difficulties in Down syndrome are:- wax in the external ear canal, 'glue ear', infection of the middle ear ( (otitis media) and sensori-neural hearing loss.

Wax in the external ear canal, particularly if it is old and hard, may interfere with hearing and should always be removed. Wax-softening eardrops should be tried in the first instance but if this procedure is not successful the wax will have to be removed by syringing or with the use of an appropriate instrument. These procedures should be performed by experienced professionals since the external ear canal is usually narrower in individuals with Down syndrome and this may make the procedure more difficult to do.

Glue Ear is one of the commonest conditions involving the ear and it has a particularly high incidence in children with Down syndrome, causing conductive hearing loss. In this condition a mucoid secretion accumulates in the middle ear and has the effect of reducing hearing levels. The situation for children with Down syndrome is different because the 'glue' is stickier, is less likely to drain away, and is more likely to become infected. The Eustachian tubes, which connect the middle ear to the upper part of the throat, are often not effective in allowing drainage from the middle ear.

There are three main techniques which are used in the treatment of glue ear.

The insertion of grommets in the ear drum allows the fluid to drain out of the middle ear into the external auditory canal. Grommets are tiny tubes with flanges at each end which are inserted through the eardrum and allow the glue to drain out. Tonsillectomy and/or adenoidectomy may also be helpful. This form of treatment is effective as long as the grommets remain in position in the eardrum. They have a tendency to become extruded (pushed out), remaining in place for about three to twelve months, but they are almost always helpful in allowing drainage and therefore improving hearing.

The disadvantages of extrusion can be avoided by creating an artificial perforation in the eardrum with a laser apparatus. These laser-produced perforations tend to heal within a few weeks but many clinicians feel that the procedure is very worthwhile.

Microsuction is a technique in which the fluid in the middle ear is sucked out through a thin needle inserted through the eardrum. This procedure usually has to be repeated several times but can be very effective. It has the advantage that there is no discharge into the external auditory canal to be dealt with.

The likelihood of Middle Ear Infections in children with Down syndrome is considerably greater than in any comparable group of children. The reasons for this are the special problems of glue ear and the fact that individuals with Down syndrome are more susceptible to infections of all kinds. The treatment of middle ear infections usually involves the use of antibiotics and may also necessitate one of the interventions listed above for glue ear.

There is a view among some otologists that grommets should not be used because of the narrow external auditory canal found in children with Down syndrome, because they are often extruded and because continual replacement may scar the ear drum. The authors, and others,[32] disagree with this view because they feel that the benefits of improved hearing upon language development and upon socialisation as well as on general intellectual development and self-confidence outweigh the possible difficulties associated with grommets. If grommets are not appropriate for a particular child, hearing aids may be offered for conductive loss.

Sensori-neural hearing loss is a poorly understood set of conditions in which the inner ear or cochlea malfunctions. The phrase is sometimes used to include problems in other parts of the central nervous system as well. It may be constitutional or develop in later life and the higher tones are mostly affected. This type of hearing loss may have a serious effect on understanding since it is these frequencies which give speech most of its intelligibility. This type of hearing loss is often overlooked in the early stages because these children do not always behave as if they are deaf. They respond to sounds of many different kinds but what they hear is a type of low frequency rumble containing little real information. Those who can lip-read may sometimes be able to communicate to some extent.

Hearing ranges for speech sounds

Figure 11. Hearing ranges for speech sounds

There is no cure in this group of conditions and those who benefit from the use of hearing aids continue to depend on them indefinitely.

The suggested program for routine audiology is firstly at about nine months of age and annually until ten years of age. After the age of ten years testing every two years is considered sufficient.

There are a number of sophisticated techniques available which test different aspects of the hearing system but it is important to remember that the only way to be sure that a child has proper sound perception is by their behavioural response to purely aural information.

Hearing Aids may be needed in a proportion of people with Down syndrome and the situation has now improved in that hearing aids are now very much more sophisticated than they used to be.

The enormous processing power of digital chips is now being used in hearing aids so that the specific requirements of children with different types of hearing loss can be compensated for much more accurately.

Getting used to wearing an aid may be a difficult problem in some cases. Children need to learn that the aid is actually helpful and a period of training may be necessary. This is often best started in a quiet room with no distracting noises so that the child can appreciate the improvement in the understanding of speech. They may then be gradually introduced into more open environments. In more difficult cases a radio-link may be helpful. This consists of a combined aid and radio receiver for the child and a transmitter-microphone for the carer. This apparatus almost totally excludes extraneous noise and allows the child to appreciate the use of aiding more easily. It is obviously very important not to give up in the face of difficulties, but to be persistent in attaining success.

Although hearing losses of up to 25 dB are usually not considered to be serious in typically developing children, there is evidence to suggest that even mild hearing loss has a deleterious effect on the educational, emotional and language development in children who have other difficulties. [see 18]

These data lend powerful support to the view that mild hearing loss is likely to have an even greater effect on children with Down syndrome.

Signing is almost always helpful in the particular situation where language development is being impeded by hearing difficulties. The advantage of this strategy is that language development can progress even in the presence of hearing difficulties.

Disorders of vision

There are a number of eye disorders which are of special relevance in Down syndrome but, apart from infections of the eyelid and conjunctiva, the commonest and most important are disorders which distort the image upon the retina. The majority of these are errors of refraction, i.e. short and long sightedness and astigmatism.

Because these errors of refraction are so common in individuals with Down syndrome it is important to have a high index of suspicion that they may be present. It appears that children and teenagers with Down syndrome rely on visual information to a relatively larger extent than other children. If this is so it means that vision is, relatively, even more important than it would normally be.

In the authors' survey,[1,2] parents reported that 39 of the 46 teenagers (85%) had visual defects and 38 of these young people were wearing glasses. Of the teenagers with vision defects, all had had an assessment within the last 18 months and all but 2 within the past 12 months. The majority were being seen by their own opticians, with 3 being seen at a hospital clinic. Of the 6 teenagers reported to have no vision problems, 4 parents could not recall the last time that their son or daughter had had an eye test. In 1987 54% of teenagers were reported to have vision defects and all but two of this group wore glasses, suggesting that there were undetected visual defects for about a third of that group and that eye care has improved for teenagers with Down syndrome in the UK.

Testing of visual function should be carried out routinely every year in all children with Down syndrome until the age of ten years, every two years during teenage and adult years and as soon as possible if there is any clue in the behaviour of the child or young person which could be accounted for by deteriorating vision. It is possible to test vision in virtually all children and young people, even those who are very young and/or who cannot speak.

Fortunately almost all errors of refraction are treatable with the use of spectacles. New developments in lens manufacture have made lightweight plastic lenses available, and for those whose who have a very flat nasal bridge, double bridge pieces can be very helpful. Elasticised bands which attach to the ear pieces, such as are used by sportsmen can be useful in preventing spectacles from falling off. It is important that glasses be kept clean at all times, so that the child is always aware that they really do make the world around them easier to see.

A spare pair of glasses should always be available - it is not worth the disruption of waiting for new pair if the current one is lost or damaged.

The employment of behavioural techniques may be necessary if the child refuses to wear the spectacles. In any event it is useful to create situations where the child realises that vision is improved with use of spectacles.

Disorders of thyroid function

The thyroid gland is a shield-shaped gland situated at the base of the neck. It produces three main hormones; thyroxine, triiodothyronine and calcitonin. Disorders of thyroid function (excluding calcitonin, which will not be dealt with here) are amongst the commonest of all endocrine disorders. In the United Kingdom as a whole the prevalence of hypothyroidism is 1.4% in females and 0.1% in males. The prevalence in individuals with Down syndrome, however, is considerably higher. For example, in the authors' recent survey of 46 teenagers in the UK, 9 teenagers (20%) had a thyroid problem, with 7 having hypothyroidism (underactive thyroid) and 2 having hyperthyroidism (overactive thyroid).[1,2]

Thyroxine (T4) and triiodothyronine (T3) control many aspects of development and metabolism and are essential for proper development and function.

Of the many types of thyroid disorder which may occur, much the most frequent is hypothyroidism - underactivity of thyroid function - and the prevalence of this condition in people with Down syndrome is considerably higher than in the population as a whole.

The main clinical features of hypothyroidism (under-functioning of the thyroid gland), are slowness, both physical and mental, dry hair, thickening of the skin, deepening of the voice and weight gain. In addition the following symptoms are also found; intolerance of cold, slow pulse, constipation, slowed growth velocity, deteriorating performance at school, delayed or absent puberty, and a large variety of mental problems.

These signs and symptoms vary a great deal between individuals both in degree and in the particular combinations expressed. The situation is complicated by the fact that the signs of hypothyroidism, which are often insidious in their onset, are frequently attributed to Down syndrome itself.

The clinical features of hypothyroidism on their own are not sufficient to make the diagnosis; this can only be made with certainty by the laboratory measurement of thyroid stimulating hormone (TSH) and the thyroid hormones.

TSH is a hormone which is produced by the pituitary gland and which stimulates the thyroid gland to produce T4 and T3. This hormone is usually used as an index of thyroid function because its concentration increases when the level of T4 and T3 falls. However, because the level of TSH may be sometimes higher than normal in the presence of normal thyroid function in people with Down syndrome, it is considered advisable to measure T4, T3 as well as TSH whenever thyroid function tests (TFTs) are performed. Because of the great importance of not missing a diagnosis of hypothyroidism all screening protocols advise performing TFTs periodically throughout life. The recommended intervals vary from once every five years to annual testing, the most popular suggestion being two-yearly testing. Even if the symptoms of a disorder can be explained in other ways, it is still useful to perform TFTs as part of the general investigation of most problems because of its relative commonness and the possibility of multiple diagnosis.

Treatment

Once the diagnosis of hypothyroidism has been made, the treatment consists of the administration of tablets containing T4 by mouth. The thyroxine contained in these tablets is identical to the thyroxine produced by the human thyroid gland and if the dosage is properly monitored should not produce problems.

After the initiation of treatment, follow-up visits should be held at three-monthly intervals until the appropriate dose has been established and every six to twelve months thereafter. Growth and weight should be measured at regular intervals and some estimate of cognitive progress made. It is also useful to try to obtain some idea of the general state of well being of the patient.

As children grow and their body weight increases the need for T4 will increase and it will be necessary to adjust the dose guided by the results of the TFTs.

Rarely it is found that the treatment is stopped, either because it is felt that the patient is 'cured' or for other reasons. It is, therefore, important to impress upon all those involved that the treatment of hypothyroidism is lifelong, that proper monitoring is necessary and supplies of T4 are always kept available.

The treatment of hypothyroidism is not difficult, is cheap, has no side effects and, because it is perfect replacement therapy, produces ideal results.

Infection in people with Down syndrome

The increased incidence of infections in people with Down syndrome is very well documented. Until the nineteen fifties it was the leading case of morbidity and mortality in Down syndrome.

Respiratory infections are particularly common, especially during the first five years of life, and infections of the skin and the bladder are also common.

The great increase in longevity in people with Down syndrome is primarily due to modern methods of treating infection. There is evidence that people with Down syndrome have this increased susceptibility to infection because their immune systems have some abnormalities. Fortunately this does not mean that they do not respond to immunisation procedures or antibiotics, but it does mean that they are prone to more frequent infections than control groups and that they are sometimes more difficult to treat.

The implications of this increased susceptibility is that antibiotics tend to be needed more frequently in people with Down syndrome and it is likely that they will need to be used earlier in the course of an infection as well.

Immunisations ought to be carried out in the normal way but it is sometimes necessary to ensure that the antibody response is adequate. Immunisation against hepatitis B is now commonly included with the usual list of childhood immunisations since the incidence seems to be higher in people with Down syndrome. This disease is highly infectious and a good case could be made for everyone to be immunised against it.

The presence of occult, or hidden infections should be suspected if a child with Down syndrome seems below par for no obvious reason. Common sites for such infections are in the bladder, the throat and tonsils, the teeth, the middle ear and the skin.

Generally, problems with infections tend to decrease as the person with Down syndrome grows older.

Table 1 shows the percentage of teenagers who suffered from infections often, and the common types of infections reported in the authors' 1987 and 1999 surveys in the UK.

Table 1. Frequency of Common Illnesses

Question Mainstream '99
(%)
Special '99
(%)
'87 Data
(%)
Often suffers from coughs 27 16 21
Often suffers from colds 42 18 30
Often suffers from sore throats 0 12 9
Often suffers from ear infections 0 13 8
Often suffers from skin infections 17 31 20
Often suffers from stomach upsets 0 26 13

The figures indicate that there has been little change in infection rates over the 12 year period. Coughs and colds seem a little more prevalent for the teenagers attending mainstream schools and stomach and skin infections more common for those attending special schools. Skin infections can become more troublesome during adolescence and good hygiene needs to be encouraged plus the use of antiseptic ointments for septic spots.

Gastro-intestinal system

People with Down syndrome are more likely to have more problems with the stomach and intestines than other comparable groups of people. One of the commonest of these is constipation. If the constipation is very serious the child should, preferably, be investigated by a paediatric gastroenterologist since there are some rather serious conditions of the gut which present in this way. If special investigations reveal no obvious reason for the constipation it may then be managed symptomatically.

Occasionally the lower part of the colon becomes greatly distended and chronically filled with faeces. This can be a difficult problem to deal with and emptying the lower colon can be difficult. The help of a physician experienced in techniques for emptying the colon may be needed.

Even if the child has a good mixed diet and has an adequate fluid intake, constipation may continue to be a problem and the management then usually consists of a combination of habit training and laxatives.

The use of laxatives should be closely monitored as to dosage and frequency since these details often determine the difference between success and failure. It seems that constipation problems do tend to resolve as children get older as only one teenager in the authors' survey group of 46 teenagers still suffered from constipation.

Cardio-vascular system

Although incidence figures vary, it is generally accepted that about 50% of babies born with Down syndrome will have a disorder of the heart. These congenital cardiac disorders vary enormously in type and severity. Many of them are relatively mild and do not need surgical intervention, some are fairly easy to deal with, while a proportion are serious and necessitate complex surgery.

Because of the high incidence of congenital cardiac defects most paediatric departments have screening programs for newborn children with Down syndrome. The use of ultrasound in screening programs has made the detection of cardiac abnormalities easier and has had the effect of allowing earlier and more effective treatment.

In the authors' recent survey of 46 teenagers in the UK, 19 (41%) had cardiac defects, for which 13 had had surgery in infancy or preschool years.

The diagnosis and treatment of cardiac disorders is highly specialised and is the province of the paediatric cardiologist and paediatric cardiac surgeon.

Detailed information on the different types of cardiac disorders and their treatment as well as support is available from the Down's Heart Group. They provide continuing support for teenagers and young adults, not just for children.

There are a small group of teenagers who have severe cardiac abnormalities that could not be surgically repaired when they were babies or young children. These young people may begin to experience increased difficulties in energy and mobility in their teenage years, and they will have reduced life expectancy.

Atlanto-axial instability

Many parents and carers are advised not to allow teenagers with Down syndrome to engage in certain sports such as trampolining and forward rolling. This advice is based on the view that people with Down syndrome are more likely to have difficulties in the top part of the spinal column.

Some understanding of the anatomy of the area may help to clarify some of the issues (see Figure 12 and Figure 13).

Front view of cervical vertebrae 1 and 2, the odontoid process and the spinal cord

Figure 12. Front view of cervical vertebrae 1 and 2, the odontoid process and the spinal cord (diagram - not to scale)

The first vertebra of the spinal column is called the 'atlas' or C1 (1st cervical vertebra). It is a roughly circular bone with two areas on its upper surface which support the skull and the atlas, in turn, rests upon the second neck vertebra which is called the 'axis' or C2 (second cervical vertebra).

The axis has a projection, called the 'odontoid process', which projects upwards inside the circle of the atlas. This bony ring, therefore, contains, among other things, the odontoid process and the upper part of the spinal cord behind it.

If the anatomy of this area is altered so that the odontoid process is pushed backward it could then press upon the spinal cord and damage it.

Side view of cervical vertebrae 1 and 2, the odontoid process and the spinal cord

Figure 13. Side view of cervical vertebrae 1 and 2, the odontoid process and the spinal cord (diagram - not to scale)

This occurrence is very rare in people with Down syndrome and the mechanisms are still not properly understood but, at present, some organisations such as the Special Olympic Committee require that people with Down syndrome have been tested for evidence of 'atlanto-axial instability' (a-a instability) as a condition for being accepted for the Special Olympics.

The test for 'a-a instability' consists of taking x-rays of the neck in several different positions and measuring the distances between various parts of the vertebrae and the spinal cord.

In 1986 the Department of Health of the United Kingdom recommended that people with Down syndrome should have their necks x-rayed before engaging in vigorous sporting activity.

However it later became evident that x-ray examination for 'a-a instability' was not a reliable way of predicting whether there was an increased likelihood of spinal damage in those people who were diagnosed as having 'a-a instability' and the original recommendations of the Department of Health that these x-rays should be carried out were withdrawn in 1995.

'Atlanto-axial instability' remains a controversial issue and although damage to the spinal cord is rare, it is important to point out that when such damage does occur it seldom does so without warning.

The signs of upper spinal cord compression usually start with weakness, new difficulties in walking, not lifting the feet properly and unsteadiness. Pain or discomfort in the neck may occur and sometimes the neck may be held in unusual positions.

Bladder and bowel function may be affected and problems with hand and arm function may be later signs.

When possible warning signs do appear it is essential that competent medical intervention is sought as soon as possible in order to establish a diagnosis and institute appropriate treatment.

It is sometimes suggested that a supportive neck collar be worn, especially by people with Down syndrome, if they have pain or discomfort in the neck. This may do more harm than good because supporting the head in this way relieves the neck muscles of the normal exercise they continually perform with the result that they become weak.

Virtually all joints need properly functioning musculature to ensure that they function well and it is, therefore, important that all muscles should maintain their tone and strength with adequate exercise.

The view of many Down syndrome medical advice groups is that there is no good evidence that any form of exercise carries an additional risk for people with Down syndrome. In the author's recent survey only 1 of 46 teenagers was reported to have 'slight' atlanto-axial instability, presumably on the basis of an X-ray result, but no symptoms were reported.

Sleep Related Breathing Problems

Difficulties in breathing during the hours of sleep are now known to be relatively common in the population as a whole and one of the commonest and most important of these is Sleep Apnoea - SA. This phrase is used to denote the situation where the passage of air in and out of the lungs is interfered with during sleep.

There are, conventionally, two forms of SA.

The commonest is obstructive sleep apnoea - OSA, which accounts for about 90% of all forms of SA. In this condition the airflow is decreased by factors which produce obstruction of varying degrees in the upper air passages. This may be caused by enlarged tonsils and/or adenoids, small size or other abnormalities of the soft tissues of the airways, infections of these tissues which may cause further narrowing, and several other factors.

Airways obstruction may lead to the level of oxygen in the blood falling and the level of carbon dioxide rising. These, and other factors lead to sleep being disturbed and partial or complete awakening, a change of position and a few deep breaths. The person usually goes back to sleep again until another apnoeic event disturbs them again. These arousal episodes may happen many times during the night and are best understood as protective strategies which have the effect of re-establishing effective air flow. OSA may be associated with strange sleep positions, snoring and restlessness as well as apnoeic episodes.

A less common form of sleep apnoea is central sleep apnoea - CPA, which comprises about 10% of the sleep apnoeas. In this condition the breathing difficulties are related to disordered movement of the diaphragm which is presumed to be caused by disturbances in the centres in the brain which control diaphragmatic movement.

SA is associated with a surprisingly diverse, and often quite serious, number of conditions. Some of the commoner ones are high blood pressure, restricted growth, lung infections and number of daytime behaviour problems such as overactivity, sleepiness and poor attention, thus illustrating the adage that 'If you have a bad night you will not have a good day'.

The incidence of SA is reported to be 10% of the population over 65 years of age and between 2 to 4% of the middle-aged population of the USA. These figures suggest that sleep disorders are an important problem and there is convincing evidence that the figures are considerably higher in people with Down syndrome. In a UK survey[35] of 91 children with Down syndrome aged from 4 to 19 years, 12% were reported to have apnoeic episodes and this incidence did not change significantly across the age range. Other features thought to be related to sleep apnoea were reported to be very frequent, with loud snoring reported for 43% , sleeping with neck extended for 30%, gagging and choking during sleep for 7%, restlessness for 60% and mouth breathing for 73% of the children with Down syndrome. The incidence of all these difficulties was significantly higher than those reported for the siblings of the children with Down syndrome, a typically developing group of children and a group with learning difficulties but not Down syndrome. The comparison groups were all of a similar age distribution to the group with Down syndrome. This study also found that the presence and severity of sleep disturbance was associated with levels of daytime behaviour difficulties and levels of maternal stress.

If there is good evidence that SA might be present and especially if there are apparently associated difficulties such as undesirable behaviours and/or physical symptoms, the diagnosis should be elucidated in a sleep laboratory where a large number of measurements are taken during an overnight sleep stay.

Once the diagnosis is confirmed a treatment strategy will be worked out so that restful, non-fragmented sleep can be re-established.

Obesity, healthy eating and exercise

The risk of becoming overweight seems to increase for young people with Down syndrome after puberty. For example, an Italian study of 160 children[36] reported that only 14% of those who had not yet reached puberty were overweight, but 66% of those who had reached puberty were overweight based on BMI - Body Mass Index. Body Mass Index is based on the relationship between the individual's height and weight.

In the authors' recent survey of 46 teenagers, 22 (48%) were considered by their parents to be overweight and most of their parents were worried about their son/daughter's weight gain and would have liked advice on how to reduce their weight. This means that parents of teenagers need to particularly aware of encouraging healthy eating and sufficient exercise for their sons and daughters. A balanced diet containing a proper mix of the four key food groups (meat and fish, vegetables and fruit, bread and grains, and dairy products) needs to be encouraged while limiting the intake of foods high in fats and sugars. This is not easy given the kinds of foods encouraged in fast-food outlets and even school canteens.

Useful practical advice on how to encourage healthy eating written by Joan Medlen, a dietician who is also the parent of child with Down syndrome, is available[37] and can be found on the Disability Solutions website.

Dental care

There are a number of dental abnormalities which are associated with Down syndrome, including late appearance of teeth, missing teeth, some abnormally shaped teeth, abnormal bite as the upper an lower teeth are not normally aligned and an increased risk of gum disease.[38] On the positive side, children with Down syndrome seem to have a significantly lower incidence of dental caries. One study reported that 43% of children with Down syndrome were completely free from tooth decay.

Delayed appearance of teeth affects 75% of children. Sometimes first primary teeth do not appear until 2 years of age, they are not complete before 4 to 5 years and may be retained until 14 to 15 years. This means that many teenagers will still be getting their secondary teeth. Some 43% of teenagers will not get the usual number of teeth and it is at this time that treatment may be required to ensure that teeth are aligned and bite corrected if possible.

All teenagers should have regular dental checks and receive appropriate treatment for dental problems and abnormalities. The incidence of gum disease is reported to be higher in adolescents with Down syndrome than in other adolescents. Gum disease is affected by oral hygiene, dietary control and regular dental visits. Teenagers should be encouraged to brush their teeth after each meal, or at least twice a day. Some authors recommend flossing once a day but this may be difficult for teenagers to manage. The advice on a healthy diet is to avoid sugary, sticky foods.

Puberty and sexual health

Teenagers with Down syndrome experience the same physical and emotional changes during adolescence as other teenagers. Two studies in the UK[3,39] have found that girls with Down syndrome may begin to menstruate about a year earlier on average but this has not been reported in American studies.[40]

The majority of teenagers with Down syndrome cope well with the changes. Most girls learn to take care of their own hygiene needs effectively during their periods. Most boys learn to masturbate only in private.

Research into fertility, sexuality and pregnancy in individuals with Down syndrome is limited. It seems that both girls and boys are fertile though fertility may be lower than is typical in the general population. However, contraception should be considered if young people are sexually active - it should not be assumed that young people with Down syndrome are not fertile. There are recorded cases of men and women with Down syndrome becoming parents.[41,42]

The sexual and emotional needs of teenagers and young people with Down syndrome are the same as those of the rest of the population. Some young people appear to be more sexually aware and active than others, and this is also true of the rest of the population. The opportunity for teenagers with Down syndrome to have a boyfriend or girlfriend and to establish a meaningful relationship may be reduced as their social lives are usually still controlled by their parents and restricted by their limited independent travel skills.

However, increasing numbers of teenagers and adults are forming close relationships, with some establishing permanent partnerships or getting married.

It is important that all young people with Down syndrome learn as much as possible about the ways in which their body is changing and about taking care of their personal hygiene. It is also important that they have good and accurate sex education, which includes all the basic biological facts and includes discussion of relationships, how sexual relationships develop and how people love and care for each other. This is not only important in order to ensure that young people with Down syndrome can enjoy happy and fulfilling relationships, but also to ensure that they are able to protect themselves from advances that they do not want or that are abusive.

Sex education can take place in small steps over a number of years, in a way that is judged to be appropriate for each individual, especially as the personalities and abilities of individuals with Down syndrome varies so widely. Teenagers with Down syndrome should receive the same health care as other teenagers, as appropriate for their sexual development and experience.

All teenagers should have some understanding of intercourse and conception. If likely to be sexually active, then information on contraception and venereal diseases may be appropriate. In the authors' experience, promiscuity in teenage years is unusual, though a wish for a steady relationship is common. Since most teenagers do not wander about the community alone, risks of abuse and concealed sexual relationships are not great. More detailed sex education can usually be provided as relationships are beginning to blossom.

In the authors' experience, most teenagers and adults understand more about sexual development, sexual activity and pregnancy than their parents and others would expect. Most teenagers and adults are also able to act in a mature and responsible way in their relationships, and understand the need for contraception.

Mental Health and Behaviour Problems

Mental disorders

Most people are aware of the physical and social changes which take place during adolescence. However, the nature of the behavioural, perceptual and emotional changes are still not very well understood. There is also some difficulty in distinguishing between more-or-less normal adjustment problems and more serious forms of mental illness.

It is difficult to obtain reliable information on the overall prevalence of mental disorders in Down syndrome because of the poor reliability of diagnosis and the difficulties in obtaining sufficiently large and representative populations of people with Down syndrome.

However, most of the published studies on people with mental disorders and Down syndrome report that virtually all the mental disorders that are found in the population as a whole may occur in people with Down syndrome and it also seems likely that the prevalence of the more serious disorders is lower than in control groups consisting of people with learning disabilities of various types.[43,44]

It may be that some disorders such as clinical depression, autistic spectrum disorders and attention deficit hyperactivity disorder are more common in people with Down syndrome but evidence for this is not very good at present. Nevertheless is important to be aware that mental disorders may occur in people with Down syndrome and that they need to be treated in the same way as in anyone else.

There may be difficulties in diagnosis where, for example, the person concerned is unable to communicate effectively or manifests the disorder in an unusual way, but it should be possible to obtain a good diagnosis and formulation with the aid of a suitable expert.

Depression

The diagnostic category that causes considerable difficulty at present is covered by the phrase 'depression'. It does seem that clinical depression and serious unhappiness are often confused with each other, and since the management of these two conditions can sometimes be very different it is important to remember that the observation that someone is feeling miserable is only the beginning of the diagnostic process and not the diagnosis itself.

It is probable that a significant number of late adolescents with Down syndrome become chronically miserable and more-or-less withdrawn because they find that many of their childhood expectations have not been realised.

The story of Katrina [not her real name] is an example.

Katrina was told that she had Down syndrome when she was about ten years of age but this was not brought up subsequently. She had two older siblings who included her in most of their leisure activities and the family always went on their, frequent, holidays together. These arrangements stopped fairly abruptly when her siblings become occupied with examinations and boy friends and Katrina found herself both friendless and confronted with the realisation that she could no longer follow in the footsteps of her siblings. She became miserable, withdrawn and consumed with feelings of inadequacy and hopelessness. It took a great deal of help and time before she began to engage with life once more.

Katrina's story is an example of a severe adjustment reaction and not of a severe mental illness.

The presentation of clinical depression is essentially the same in Down syndrome as in any control group.

Self talk

A large percentage of people with Down syndrome of all ages tend to talk to themselves and/or have imaginary friends and this is sometimes a cause concern in their parents and carers. In virtually all cases this perfectly normal and has nothing to do with the hallucinations found in serious mental illnesses.[3,4]

Almost all typically developing children go though a stage of 'self talk' and this is progressively internalised with age. A fair number continue this practice throughout their lives regardless of their level of intelligence.

It is now generally accepted that self talk is merely a form of thinking aloud and serves an adaptive function by helping to think about the various tasks and problems of daily life.

Treatment

None of the above considerations affect the treatment of any person with Down syndrome who has been diagnosed as having a mental disorder since the management of theses disorders in people with Down syndrome should be the best conventional treatment available.

However, because the diagnosis if mental illnesses can some times be difficult and because the likelihood of more than one diagnosis being present at the same time is fairly high it is important exclude conditions such as thyroid diseases, problems with hearing and vision and sleep apnoea..

Behaviour problems

Behaviour problems, autism and ADHD are sometimes considered as mental health issues. These are discussed in the first section of this module (see 'Teenagers with more severe developmental delays').