The prevalence of mental illness in those with learning disabilities is estimated at around 28%, and 3% for psychosis specifically (Dept of Health, 2001; Smiley, 2005). Yet of all psychotropic medications prescribed in this population, 30-50% are antipsychotics (Tsiouris, 2010). So what else are they being prescribed for?

Around 12.5% of those with a learning disability show challenging behaviour (Smiley, 2005), which is usually managed using behavioural strategies, but in more severe cases antipsychotics may be considered.

Antipsychotics are recommended by NICE to help manage challenging behaviour in those with a learning disability if:

• Other challenging behaviour interventions fail
• Treating any coexisting health problems does not improve behaviour
• The risk to the person or others is severe (NICE, 2015)

This study aimed to identify the incidence of mental illness and challenging behaviour in those with learning disabilities, and to explore the prescription of psychotropic drugs in this population.

Methods

This is a cohort study, using data from The Health Improvement Network (THIN) from 1999 to 2013. THIN is a primary care database with more than 3.7 million active patients from 571 general practitioners (GPs). The patients are representative of the UK population in terms of age, sex, medical conditions and death rates. THIN contains information on symptoms, diagnoses, secondary care referrals, treatments and prescriptions, and demographic information.

The researchers excluded anyone who contributed less than 12 months of data or was under 18. They identified participants and determined outcomes using Read codes (standardised clinical terms), the final list of which were refined by three psychiatrists specialising in learning disabilities and one GP.

The outcomes of interest were as follows:

• Neuropsychiatric diagnoses: schizophrenia, bipolar, other psychosis, depression, anxiety, dementia, autism, epilepsy
• Challenging behaviour: aggressive, self injury, stereotypic behaviour, agitation, disruptive or destructive acts, withdrawn behaviour, arson, sexual misconduct
• Severity of intellectual disability
• Psychotropic drug prescription: antipsychotics, antidepressants, mood stabilisers, anxiolytics, hypnotics, antidementia drugs, drugs for ADHD.

Results

There were 33,016 people who met the inclusion criteria, and their mean follow-up time was 5.5 years (interquartile range: 2.2-11.5 years).

In total, 21% of participants had a diagnosis of any mental illness at study entry, including 7% with a diagnosis of a severe mental illness. These figures were 34% and 9% respectively at study end, with an incidence rate of 262 new records of mental illness per 10,000 person years during follow-up.

At study entry, 25% of participants showed challenging behaviour, and 36% at study end.

A history of psychotropic drug prescription was present in 49% of participants at study entry, and 63% by study end. The incidence rate of new prescription of any psychotropic drugs over the follow-up period was 518 per 10,000 person years.

A positive association was found between challenging behaviour and degree of intellectual disability. Those with a record of challenging behaviour were more than twice as likely to receive a prescription for antipsychotics compared with those without a record of challenging behaviour, after neuropsychiatric diagnosis was controlled for.

Of those with a history of antipsychotic prescription, 71% had no record of severe mental illness, and 26% had no record of severe mental illness or of challenging behaviour.

Conclusions

There are far more people with learning disabilities being prescribed psychotropic drugs than there are with a recorded mental illness. In particular, antipsychotics are very commonly prescribed to those presenting with challenging behaviour who do not have a record of any psychiatric comorbidity.

It is as yet unclear why antipsychotics are being prescribed so commonly for those without a severe mental illness, particularly in the absence of challenging behaviour. As the authors state:

Changes are needed in the prescribing of psychotropics for people with intellectual disability.

Strengths and limitations

The researchers note that the THIN database is “a record of real life clinical practice in UK primary care and thus provides an accurate and representative insight into contemporary care”. It is true that this insight would be difficult to gain otherwise, and particularly on such a large scale. The database has also been shown to be representative of the UK population in terms of demographics and prevalence of major conditions (Blak et al, 2011).

However, the use of the THIN database is somewhat limiting in that it is likely that both learning disabilities (particularly mild) and challenging behaviour are under-reported to GPs. Indeed, the estimated prevalence of intellectual disability in the THIN database was slightly lower than usual estimates. Furthermore, certain details are not always recorded by GPs, such as severity of intellectual disability and the reason for prescription of medication, limiting our interpretation and understanding of the study results.

It is unclear why some exclusions, such as people under 18 years old, were made by the researchers. The mental illness code lists were also restrictive, ignoring (for example) personality disorders and substance misuse.

Summary

Qualitative research should be conducted to address the following questions:

1. Why are antipsychotics being prescribed so commonly in those with learning disabilities in the absence of mental illness?
2. Why are antipsychotics being prescribed so often to manage challenging behaviour?

It may be that we are underestimating the prevalence of psychosis in this population (and thus under-treating it), or prescribing antipsychotics for behaviour unrelated to psychosis, possibly leaving other health problems untreated (Northfield, 2015).

The accessibility and efficacy of alternative strategies of managing challenging behaviour should also be addressed. The short-term side effects of antipsychotics can be extremely unpleasant, and the long-term side effects potentially serious. Harmful effects on learning and cognitive abilities may be particularly detrimental to those with an intellectual disability. It is important that patients, relatives and carers are provided with adequate information about psychotropic drugs and their side effects, and are told about the availability of other support and management strategies.

Evidence is lacking in terms of the efficacy of antipsychotics when prescribed for challenging behaviour as well as their long-term effects (Brylewski et al, 2004; Matson et al, 2012), and a 2008 RCT showed no significant benefit on challenging behaviour over placebo (Tyrer et al, 2008). Cost-effectiveness research is also lacking, considering the high level of monitoring required with antipsychotics.

From an evidence-based medicine point of view, there is not enough evidence for the efficacy and safety of these drugs in this population for them to be widely prescribed. From a human perspective, we should be demanding an explanation for the frequency with which this class of powerful drugs are being prescribed to a vulnerable group of people.

Links

Primary paper

Sheehan R, Hassiotis A, Walters K. et al (2015) Mental illness, challenging behaviour, and psychotropic drug prescribing in people with intellectual disability: UK population based cohort study. BMJ 2015 351 h4326.

Other references

Blak B, Thompson M, Dattani H. et al (2011) Generalisability of The Health Improvement Network (THIN) database: demographics, chronic disease prevalence and mortality rates. J Innov Health Inform 2011 19(4) 251-255.

Brylewski J, Duggan L. (2004) Antipsychotic medication for challenging behaviour in people with learning disability. Cochrane Database Syst Rev 2004 3. [PubMed abstract]

Department of Health. (2001). Valuing People: A New Strategy for Learning Disability for the 21st Century – Cm 5086 (PDF). Department of Health website, last accessed 27 May 2016.

Matson JL, Neal D, Kozlowski AM. (2012) Treatments for the Challenging Behaviours of Adults With Intellectual Disabilities. Can J Psychiatry 2012 57(10) 587. [PubMed abstract]

National Institute for Health and Clinical Excellence. (2015) Challenging behaviour and learning disabilities: prevention and interventions for people with learning disabilities whose behaviour challenges (NG11). NICE guidelines website, last accessed 27 May 2016.

Northfield J. Psychotropic medications: scale and patterns of prescribing to people with learning disabilities. The Learning Disabilities Elf, 29 July 2015.

Smiley E. (2005) Epidemiology of mental health problems in adults with learning disability: an update. Adv Psychiatr Treat 2005 11(3) 214-22.

Tsiouris JA. (2010) Pharmacotherapy for aggressive behaviours in persons with intellectual disabilities: treatment or mistreatment? J Intellectual Disabil Res 54(1) 1-6. [Pubmed abstract]

Tyrer P, Oliver-Africano PC, Ahmed Z. et al (2008) Risperidone, haloperidol, and placebo in the treatment of aggressive challenging behaviour in patients with intellectual disability: a randomised controlled trial. The Lancet 2008 371(9606) 57-63. [PubMed abstract]

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