LEARNING DISABILITIES

Health Evidence Bulletins - Wales

Literature searches completed on: 19th April 1999

7: Medical Conditions in People with Intellectual Disability 

This bulletin is a supplement to, not a substitute for, professional skills and experience. Users are advised to consult the supporting evidence for a consideration of all the implications of a recommendation.

The Statements The Evidence
7.1 Medical Conditions – General
7.1a. The frequency of most common medical conditions is similar in adults with intellectual disability and the general population. There is however an increased frequency of thyroid disorders, non-ischaemic heart disorders, and sensory (visual and hearing) impairmenti,ii. i. Kapell D, Nightingale B, Rodriguez A, Lee JH, Zigman WB, Schuff N. Prevalence of chronic medical conditions in adults with mental retardation: comparison with the general population. Mental Retardation 1998: 36(4): 269-79
(Type IV evidence – use of standardised mortality ratios based on the review of medical records and interviews with care-givers of 278 adults with intellectual disability, with and without Down syndrome, 45-74 years of age)
ii. Beange H, McElduff A, Baker W. Medical disorders of adults with mental retardation: a population study. American Journal on Mental Retardation 1995; 99(6): 595-604
(Type IV evidence – comparison of rates of medical disorders among 202 adults with intellectual disability between age 20 and 50 years and a control group of 619 non-intellectually disabled adults)
7.1b. Compared with non-Down syndrome adults with intellectual disability, people with Down syndrome have a significantly lower rate of hypertensioni. i. Kapell D, Nightingale B, Rodriguez A, et al. Prevalence of chronic medical conditions in adults with mental retardation: comparison with the general population. Mental Retardation 1998; 36(4): 269-79
(Type IV evidence - use of standardised mortality ratios based on the review of medical records and interview with care-givers of 278 adults with intellectual disability, with and without Down syndrome, 45-74 years of age)
7.1c. People with intellectual disability have lower levels of arthritis and back pain compared to the general populationi. i. Welsh Office. Welsh Health Survey 1995. London: HMSO, 1996
(Type IV evidence – postal survey of a random sample of 4000 people with intellectual disability with a 56% useable response rate, N=2240)

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7.1d. People with intellectual disability have higher levels of impaired vision compared to the general populationi. i. Welsh Office. Welsh Health Survey 1995. London: HMSO, 1996
(Type IV evidence – postal survey of a random sample of 4000 people with intellectual disability with a 56% useable response rate, N=2240)
7.1e. People with intellectual disability have higher levels of impaired hearing (14.2%) compared to the general population (11.7%)i. i. Welsh Office. Welsh Health Survey 1995. London: HMSO, 1996
(Type IV evidence – postal survey of a random sample of 4000 people with intellectual disability with a 56% useable response rate, N=2240)
7.1f. People with intellectual disability have fewer natural teeth (less than 20 including teeth which have been capped or filled) compared to the general populationi.
One third of children with mild, moderate and severe intellectual disability have high levels of poor oral hygiene, but this is no higher than the general populationii.
Children with borderline or mild intellectual disability have the poorest dental condition and worst dental care with the lowest level of restorative care (restorative index 43.9%). 22% do not brush daily and over 90% do not receive any help with toothbrushing from their parents or carersii,iii.
Oral health care guidelines for people with a learning disability are due for publication in February 2001iv.
i. Welsh Office. Welsh Health Survey 1995. 1996: HMSO, London
(Type IV evidence – postal survey of a random sample of 4000 people with intellectual disability with a 56% useable response rate, N=2240)
ii. Declerck D. Vinckier F. Gizani S et al. [Status of the teeth and degree of care in handicapped in Flanders]. [French] Revue Belge de Medecine Dentaire. 1995: 50(3): 9-24
(Type IV evidence: comparison of 12-year old children with intellectual disability with age-matched children without intellectual disability in Flanders regarding general caries prevalence, caries distribution and total caries experience, Belgium)
iii. Gizani S, Declerck D, Vinckier F et al. Oral health condition of 12-year-old handicapped children in Flanders (Belgium). Community Dentistry & Oral Epidemiology. 1997: 25(5): 352-7
(Type IV evidence: observational study of 625 12-year-old children with mild, moderate and severe intellectual disability living in Flanders, Belgium)
iv. Oral Health Care Guidelines for People with a Learning Disability will be available from the Royal College of Surgeons (http://www.rceng.ac.uk) or the British Society for Disability and Oral Health (http://www.bsdh.org.uk).

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7.1g. People with intellectual disability are less likely to smoke (19.2% smokers / ex-smokers) compared to the general adult population (63.1% smokers / ex-smokers)i. i. Welsh Office. Welsh Health Survey 1995. London: HMSO, 1996
(Type IV evidence – postal survey of a random sample of 4000 people with intellectual disability with a 56% useable response rate, N=2240)
7.2 Hypothyroidism
7.2a. Subclinical hypothyroidism* is present in one third of children and adults with Down syndrome. Clinically manifested hypothyroidism can be detected in 2.3% of children with Down syndromei,ii.
*( high basal level TSH, low total or free T4)
i. Karlsson B, Gustafsson J, Hedov G, Ivarsson S-A, Anneren G. Thyroid dysfunction in Down's syndrome: relation to age and thyroid autoimmunity. Archives of Disease in Childhood 1998; 79(3): 242-5
(Type IV evidence – longitudinal study of 85 patients with Down syndrome aged up to 25 years)
ii. Rubello D, Pozzan GB, Casara D, et al. Natural course of subclinical hypothyroidism in Down's syndrome: prospective study results and therapeutic considerations. Journal of Endocrinological Investigation 1995; 17: 35-40
(Type IV evidence – Two to seven year follow-up of 344 people with Down syndrome, 257 age- and sex-matched healthy subjects, and 120 parents of subjects with Down syndrome)
Antithyroid Antibodies

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7.2b. The presence of antithyroid antibody is higher amongst people with Down syndrome (18%) when compared with a control group of non-Down syndrome subjects (5.8%)i. i. Rubello D, Pozzan GB, Casara D, et al. Natural course of subclinical hypothyroidism in Down's syndrome: prospective study results and therapeutic considerations. Journal of Endocrinological Investigation 1995; 17:35-40
(Type IV evidence – two to seven-year follow-up study of 344 people with Down syndrome, 257 age- and sex-matched healthy subjects, and 120 parents of subjects with Down syndrome)
Hepatitis B and Autoimmune Thyroiditis
7.2c. The frequency of thyroiditis in people with Down syndrome who are also carriers of HBsAg is three times higher than in people with Down syndrome who are non-carriers. They should be regularly monitored for the development of thyroid disease. This does not apply to non-Down syndrome people with intellectual disabilityi.
(Health gain notation – 2 "likely to be beneficial")
i. May P, Kawanishi H. Chronic hepatitis B infection and autoimmune thyroiditis in Down syndrome. Journal of Clinical Gastroenterology 1996; 23(3): 181-4
(Type IV evidence – case-controlled study of 57 adults with Down syndrome and 450 age-, sex- and environmentally matched disabled people without Down syndrome)
Screening for Thyroid Function
7.2d. People with Down syndrome should be screened annually for thyroid function. Antithyroid antibodies are rare in children under 8 years of age but titres subsequently increase with agei,ii,iii.
(Health gain notation – 2 "likely to be beneficial")
i. Karlsson B, Gustafsson J, Hedov G, Ivarsson S-A, Anneren G. Thyroid dysfunction in Down's syndrome: relation to age and thyroid autoimmunity. Archives of Disease in Childhood 1998; 79(3): 242-5
(Type IV evidence – longitudinal study of 85 patients aged up to 25 years)
ii. Rubello D, Pozzan GB, Casara D, et al. Natural course of subclinical hypothyroidism in Down's syndrome: prospective study results and therapeutic considerations. Journal of Endocrinological Investigation 1995; 17: 35-40
(Type IV evidence – two to seven-year follow-up study of 344 people with Down syndrome, 257 age- and sex-matched healthy subjects, and 120 parents of subjects with Down syndrome)
iii. Rooney S, Walsh E. Prevalence of abnormal thyroid function tests in a Down's syndrome population. Irish Journal of Medical Science 1997; 166(2): 80-2
(Type IV evidence - observational study of 36 subjects)
7.3 Epilepsy

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7.3a. 14-24% of people with an intellectual disability are affected by epilepsy.
The frequency of life-time history of epilepsy ranges from 7-15% of people with mild to moderate intellectual disability, 45-67% of people with severe intellectual disability and 50-82% of people with profound intellectual disability. The prevalence also varies according to the age of patients and the aetiology of intellectual disabilityi,ii,iii,iv,v.
The cumulative incidence of epilepsy at 22 years of age is much higher among those intellectually disabled people who also have cerebral palsy (38%) compared to those who do not (15%)ii.
i. Rutter M, Tizand J, Yule W, et al. Research Report: Isle of Wight Studies 1964-1974. Psychological Medicine 1976; 6: 313-32
(Type IV evidence – several epidemiological studies of children in the Isle of Wight)
ii. Goulden KJ, Shinnar S, Koller H, Katz M, Richardson SA. Epilepsy in children with mental retardation: a cohort study. Epilepsia 1991; 32(5): 690-697
(Type IV evidence - prospective cohort study of 221 children with intellectual disability born in Aberdeen between 1951 and 1955)
iii. McGrother CW, Hauck A, Bhaumik S, Thorp C, Tomb N. Community care for adults with learning disability and their carers: needs and outcomes from the Leicestershire register. Journal of Intellectual Disability Research 1996; 40(2): 183-90
(Type IV evidence - cross sectional study of 2117 adults with intellectual disability and 982 carers)
iv. Shepherd C, Hoskins G. Epilepsy in school children with intellectual impairment in Sheffield: the size and nature of the problem and its implications in service provision. Journal of Mental Deficiency Research 1989; 33: 511-14
(Type IV evidence – a study of the prevalence and nature of epilepsy in all children between the ages of 5 and 16 years in Sheffield, UK)
v. Deb S. Epidemiology and treatment of epilepsy in patients who are mentally retarded. CNS Drugs 2000; 13(2): 117-28
(Type V evidence – expert opinion based on a review of observational, experimental and randomised controlled trials)

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7.3b. False positive and false negative diagnoses of epilepsy in people with intellectual disability are possiblei. i. Alvarez N, Besag F, Iivanainen M. Use of antiepileptic drugs in the treatment of epilepsy in people with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 1-15
(Type V evidence – expert opinion based on a review of the literature)
7.3c. For people with intellectual disability multiple seizure types are common and up to three-quarters of patients remain refractory to treatment. Tonic-clonic seizures are the most common type of epilepsy in people with an intellectual disability (60%). Complex partial seizures are the second most common type (20%).
Compared with the general population, seizure types such as absences (typical and atypical), myoclonus, tonic and atonic are more common among adults with an intellectual disabilityi,ii.
i. Deb S, Joyce J. Characteristics of epilepsy in a population based cohort. Irish Journal of Psychological Medicine 1999; 16(1): 5-9
(Type IV evidence - cross sectional study of 143 adults with intellectual disability and epilepsy)
ii. Branford D. Bhaumik S. Duncan F. Epilepsy in adults with learning disabilities. Seizure 1998; 7(6): 473-7
(Type IV evidence - cross sectional study of adults with intellectual disability and epilepsy)
Assessment
7.3d. EEG remains difficult to perform in a proportion of people with an intellectual disability. EEG abnormality is detected in a high proportion of adults with an intellectual disability and epilepsy (>90%). In most cases EEG abnormality is non-specific such as excessive background slow wave. In 50% of cases the abnormality includes epileptiform changes in the EEGi,ii. i. Deb S. Electrophysiological correlates of psychopathology in individuals with mental retardation and epilepsy. Journal of Intellectual Disability Research 1995; 39(2): 129-35
(Type IV evidence - cross sectional study of 100 adults, with intellectual disability and epilepsy, randomly selected from hospital and community settings)
ii. Deb S, Joyce J. Characteristics of epilepsy in a population based cohort. Irish Journal of Psychological Medicine 1999; 16(1): 5-9
(Type IV evidence - cross sectional study of 143 adults with intellectual disability and epilepsy)
Treatment and Care

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7.3e. Reducing polypharmacy use of antiepileptic drugs in institutionalised people with intellectual disability is associated with a reduced frequency of seizures and a reduced frequency of behavioural disorders and improved quality of life. Large scale studies including community based cohorts are required to confirm this apparent benefiti,ii.
(Health gain notation – 2 "likely to be beneficial")
i. Pellock JM, Hunt PA. A decade of modern epilepsy therapy in institutionalized mentally retarded patients. Epilepsy Research 1996; 25(3): 263-8
(Type IV evidence - prospective cohort study of 244 institutionalised patients)
ii. Mirza WU, Credeur LJ, Penry JK. Results of antiepileptic drug reduction in patients with multiple handicaps and epilepsy. Drug Investigation 1993; 5(6): 320-26
(Type IV evidence – open prospective study of 44 institutionalised patients)
7.3f. Phenobarbitone is no longer a drug of choice for people with intellectual disability. It can cause cognitive deficiency and serious behavioural disturbancesi.
(Health gain notation – 6 "likely to be ineffective or harmful")
i. Alvarez N. Barbiturates in the treatment of epilepsy in people with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 16-23
(Type V evidence – expert opinion based on a review of experimental and observational studies, but no randomised controlled trials)
7.3g. Phenytoin can not be recommended as a first line drug for treatment of epilepsy in people with intellectual disability due to its potentially severe adverse effects on the central nervous systemi.
(Health gain notation – 6 "likely to be ineffective or harmful")
i. Iivanainen M. Phenytoin: effective but insidious therapy for epilepsy in people with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 24-31
(Type V evidence – expert opinion based on a review of experimental and observational studies)
7.3h. Sodium Valproate is a drug of first choice for a broad range of epileptic seizures in people with intellectual disability. These include: generalised tonic-clonic, tonic, clonic, atonic (drop attacks), myoclonic, absence and partial seizures with or without secondary generalisationi.
(Health gain notation – 2 "likely to be beneficial")
i. Friis ML. Valproate in the treatment of epilepsy in people with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 32-5
(Type V evidence – expert opinion based on a review of experimental and observational studies)
7.3i. Carbamazepine is a drug of first choice for a range of epileptic seizures in people with intellectual disability. These include partial seizures with or without secondary generalisation and generalised tonic-clonic seizuresi.
(Health gain notation – 3 "trade-off between beneficial and adverse effects")
CARBAMAZEPINE MAY MAKE ABSENCE, MYOCLONIC AND ATONIC (DROP ATTACKS) SEIZURES WORSEi.
i.Waisburg H, Alvarez N. Carbamazepine in the treatment of epilepsy in people with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 36-40
(Type V evidence – expert opinion based on a review of experimental and observational studies)

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7.3j. Oxcarbazepine is similar to Carbamazepine in its indication, but has fewer adverse effects. It is useful in the treatment of epilepsy in people with intellectual disability including partial seizures with or without secondary generalisation and generalised tonic-clonic seizuresi.
(Health gain notation – 2 "likely to be beneficial")
i.Gaily E, Granström M-L, Liukkonen E. Oxcarbazepine in the treatment of epilepsy in children and adolescents with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 41-5
(Type III evidence – open-label non-controlled (non-randomised) prospective study of 40 children and adolescents with intellectual disability, with a mean follow-up of 18.8 months)
7.3k. Lamotrigine is an effective broad-spectrum antiepileptic treatment with minimal adverse effects in people with intellectual disability. It is effective in generalised tonic-clonic, partial seizures with or without secondary generalisation, Lennox-Gastaut and West Syndromei.
(Health gain notation – 2 "likely to be beneficial")
i. Besag FMC. Lamotrigine in the treatment of epilepsy in people with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 50-6
(Type V evidence – expert opinion based on a review of experimental and observational studies)
7.3l. Vigabatrini, Gabapentinii, Topiramateiii and Tiagabineiv are effective as add-on therapies in the treatment of partial seizures in people with intellectual disability.
(Health gain notation – 2 "likely to be beneficial")
Vigabatrin is effective in the treatment of infantile spasmsi.
(Health gain notation – 3 "trade off between beneficial and adverse effects")

THERE IS EVIDENCE OF AN ASSOCIATION BETWEEN VIGABATRIN AND VISUAL FIELD DEFECTS (BILATERAL VISUAL FIELD CONSTRICTION)i. IT IS SOMETIMES ASYMPTOMATIC. ONE STUDY FOUND A DEFINITE BILATERAL FIELD DEFECT IN 39% OF PATIENTS, WHICH PERSISTED AFTER TREATMENT WAS WITHDRAWNv.

i. Ylinen A. Antiepileptic efficacy of vigabatrin in people with severe epilepsy and intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 46-9
(Type III evidence – evaluation study in a group of patients with refractory epilepsy; 36 patients with intellectual disability and 75 patients with normal intelligence)
ii. Mikati MA, Choueri R, Khurana DS, Riviello J, Helmers S, Holmes G. Gabapentin in the treatment of refractory partial epilepsy in children with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 57-62
(Type III evidence - non-randomised trial of 26 children and adolescents with intellectual disability and 6 with normal intelligence, all suffering from refractory partial seizures)
iii. Kerr MP. Topiramate: uses in people with an intellectual disability who have epilepsy. Journal of Intellectual Disability Research 1998; 42(S1): 74-9
(Type V evidence – expert opinion based on a review of experimental and observational studies)
iv. Kälviäinen R. Tiagabine: a new therapeutic option for people with intellectual disability and partial epilepsy. Journal of Intellectual Disability Research 1998; 42(S1): 63-7
(Type V evidence – expert opinion based on a review of experimental and observational studies)
v. Lawden MC, Eke T, Degg C, Harding GFA, Wild JM. Visual field defects associated with vigabatrin therapy. Journal of Neurology, Neurosurgery and Psychiatry 1999; 67: 716-722
(Type IV evidence – prevalence study of visual defects in 33 patients with epilepsy taking vigabatrin (31 assessed) and 16 unexposed control patients with epilepsy)

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7.3m. Zonisamide is effective in the treatment of partial and generalised seizures in people with intellectual disabilityi.
(Health gain notation – 2 "likely to be beneficial")

NOTE: ZONISAMIDE IS NOT CURRENTLY LICENSED IN THE UK

i. Iinuma K, Minami T, Cho K, Kajii N, Tachi N. Long-term effects of zonisamide in the treatment of epilepsy in children with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 68-73
(Type III evidence - non-randomised controlled trial of 115 children with epilepsy (66 with intellectual disability and 49 with normal intelligence)
7.3n. Benzodiazepines including clobazam, nitrazepam and clonazepam can be used as short-term adjuncts in the treatment of epilepsy in people with intellectual disabilityi.
Long term use of benzodiazepines is not recommended due to the effects on tolerance and symptoms associated with withdrawali.
(Health gain notation – 3 "trade off between beneficial and adverse effects")
i. Isojärvi JIT, Tokola RA. Benzodiazepines in the treatment of epilepsy in people with intellectual disability. Journal of Intellectual Disability Research 1998; 42(S1): 80-92
(Type V evidence – expert opinion based on a review of experimental and observational studies)
7.3o. Intranasal and buccal spray of Midazolam may have significant advantages over rectal diazepam as a rescue medication for prolonged recurrent seizures or seizures associated with hypoxia in people with intellectual disabilityi,ii,iii.
Intranasal midazolam is as effective as intravenous diazepam in the treatment of prolonged febrile seizures in children ii.
Buccal midazolam is at least as effective as rectal diazepam in the acute treatment of children and
adolescents iii.
(Health gain notation – 2 "likely to be beneficial")
i. Scheepers M, Scheepers B, Clough P. Midazolam via the intranasal route: an effective rescue medication for severe epilepsy in adults with a learning disability. Seizure 1998; 7: 509-12
(Type IV evidence – case studies of 3 patients with epilepsy)
ii. Lahat E, Goldman M, Barr J. Bistritzer T, Berkovitch M. Comparison of intranasal midazolam with intravenous diazepam for treating febrile seizures in children: prospective randomised study. British Medical Journal 2000; 321: 83-86
http://www.bmj.com/cgi/content/full/321/7253/83
[accessed 8.12.00]
(Type II evidence – randomised controlled trial (intranasal midazolam or intravenous diazepam) of 47 children, aged 6 months to 5 years, with prolonged febrile seizures)
iii. Scott RC, Besag FMC, Neville BGR. Buccal midazolam and rectal diazepam for treatment of prolonged seizures in childhood and adolescence: a randomised trial. Lancet 1999; 353: 623-626
(Type II evidence – randomised controlled trial of young people, aged 5-19, treated with buccal midazolam (40 episodes in 14 patients) or rectal diazepam (39 episodes in 14 patients))
7.3p. A substantial proportion of epileptic patients with an intellectual disability improve following neurosurgery with some becoming totally seizure freei.
(Health gain notation – 2 "likely to be beneficial")
i. Henriksen O, Bjørnaes H, Røste GK. Epilepsy surgery in metal retardation: the role of surgery. In Sillanpää M, Gram L, Johannessen SI, Tomson T (eds.) Epilepsy and Mental Retardation. Philadelphia:Wrightson Biomedical Publishing Ltd, 1999. pp. 105-113
(Type V evidence – expert review of the literature – no randomised controlled trials reported)

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Health Evidence Bulletins: Wales, Duthie Library, UWCM, Cardiff CF14 4XN. e-mail: weightmanal@cardiff.ac.uk