Statement of the problem
The prevalence of epilepsy in people with an intellectual disability (ID) is apparently higher than in the general population. The outlook for individuals with both epilepsy and ID depends on the presence of any associated conditions. However, there have been few epidemiological studies of the prevalence of epilepsy and associated problems within a representative adult ID population to inform the development of policy.
Method
This was a population-based prevalence study using the Leicestershire Learning Disability Register. Prevalence was estimated from the number of individuals with reported epilepsy identified from structured home interviews with carers. Associations with epilepsy were investigated for a range of defined physical, mental and skill attributes. Logistic regression was done with and without adjustment for age, sex and level of understanding to identify specific and holistic links respectively.
Results
The prevalence of epilepsy was 26%. Among those with epilepsy, 68% experienced seizures despite anti-epileptic medication. Epilepsy showed a significant association with low levels of understanding. Specific morbid associations included wetting (adjusted odds ratio 2.7), soiling (2.2), walking (2.5), daily living skills (1.6), poor speech (2.2), lack of empathy (1.5), mood swings (1.5), being uncooperative (1.6), seeking attention (1.7) and disturbing others at night (1.9). Holistic associations included a wider range of physical and mental problems and global skills deficits.
Conclusions
The high prevalence, associated morbidities and global skills deficits make epilepsy care for adults with ID important and complex. Specialist epilepsy services for this population need a multidisciplinary skills mix.
The prevalence of epilepsy in people with an intellectual disability (ID) appears to be much higher than in the general population.1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 However, most of the previous studies have been confined to children with ID and cannot be generalised to adults with ID because of potential developments in later life. Community-based studies of epilepsy in adults with ID show a prevalence of 16–26%.1, 5, 10 and 11 A review of existing studies highlighted the methodological problems, particularly case ascertainment and selection bias.12 It is important to establish the extent of inequality in the prevalence of epilepsy between a representative group of adults with ID and the general population as a basis for providing equitable services for the socially neglected ID population.
Clinical studies of adults with ID have identified higher rates of behaviour and psychological problems in those who also have epilepsy compared with those without epilepsy.13, 14 and 15 However, there have been few epidemiological studies of morbidity associated with epilepsy in the adult ID population as a whole. Knowledge of physical and mental health problems specifically associated with epilepsy in adults with ID may improve understanding of co-morbid connections and help to focus therapeutic efforts.
Both epilepsy and ID may be caused by a range of genetic, congenital, traumatic and other pathological processes.1, 2 and 5 The risk of epilepsy is greater in those with additional neurological impairments as well as ID.6 It is generally accepted that epilepsy arises secondarily to brain damage or abnormality, which is the presumed cause of ID, but the precise relationship between ID and epilepsy is not always clear.1 and 8 It is important to identify factors related to the individual as a whole, incorporating both epilepsy and ID, as a basis for planning and delivering services.
The outlook for people with both epilepsy and ID varies according to the underlying and associated conditions.5, 6, 16 and 17 The latter include adaptive behaviour problems, which manifest as a lack of skills essential for living in our complex society.15 These have implications both for the management of individual patients and for planning services for those with multiple disabilities.
A key principle of the government's white paper Valuing People 18 is to enable people with ID to access mainstream services. However, professionals in primary care may have limited knowledge and experience of managing people with ID or epilepsy. 19 Services for epilepsy in the UK are highly variable and few are orientated towards the needs of individuals with ID. 20 Psychiatrists in specialist ID services often lack experience of diagnosing and managing epilepsy. An epidemiological perspective on the extent of epilepsy in adults with ID and factors specifically and holistically associated with it may inform the debate about the mix of appropriate service provision for this group.
The aims of the study were to estimate the prevalence of epilepsy in adults with ID; and, among adults with ID, to compare the frequency of overall and specific physical disabilities, deficits in daily living skills, autistic traits, psychological symptoms and behaviour problems in those with and without epilepsy.
The prevalence of epilepsy reported from the Leicestershire Learning Disability Register was at least 26 times higher than in the general adult population. There was no particular concentration of epilepsy in any gender, ethnic or residential subgroups. Morbidities specifically associated with epilepsy included low level of understanding, incontinence (urinary and faecal), difficulty in walking, poor speech, lack of empathy, mood swings, uncooperativeness, seeking attention and disturbing others at night. Holistically, accompanying problems included a wider range of physical, autistic, psychological and behavioural problems, probably linked to the associated low level of understanding. These problems and the attendant skills deficits make epilepsy care more difficult for people with ID and suggest the need for a multidisciplinary skills mix.
