Polypharmacy Profiles and Predictors Among Adults with Autism Spectrum Disorders

Background: Mental health and behavioural issues are extremely common in individuals with autism spectrum disorders (ASD) and the primary treatment for these issues is pharmacological. Recent studies estimate that over one half of young people with ASD are prescribed psychotropic medications with one fifth taking two or more (Aman, Lam, et al., 2003; Langworthy-Lam, et al., 2002; Mandell, at al., 2008). Greater age, more restrictive housing, and more severe autism are all associated with increased medication use (Aman, et al., 2003; 2005). Despite this, very few studies have examined drug prevalence rates or patterns of medication use among adults with ASD.

Objectives: To examine the medication profiles and risk factors for polypharmacy in a clinical sample of Canadian adults with ASD.

Methods: As part of a larger project examining behavioural crises and developmental disabilities, medication information was collected on 142 adults with ASD from three urban centers in Ontario, Canada. Each of these adults experienced a “psychiatric or behavioural crisis” and was served by participating social service or mental health agencies for people with developmental disabilities. Medication information was recorded by agency staff alongside other demographic and clinical information (e.g., risk behaviours, service use, comorbid medical and psychiatric conditions).

Results: Sixty-four percent of adults with ASD reported to be taking psychotropic medication and over three quarters of those taking psychotropic medications were prescribed antipsychotics. Of those prescribed medications, 30% percent were taking anxiolytics, 25% antidepressants, and 18% mood stabilizers. Over half were prescribed non-psychotropic medications and none reported taking stimulants.

Almost half of adults (46%) were prescribed 2 or more psychotropic medications and the majority of these individuals (83.3%) resided in group homes.

Psychiatric support, residence, and aggression predicted multiple medication use.  Adults with ASD living in a group home were 11 times more likely to be prescribed 3 or more psychotropic medications and 3 times more likely to be prescribed 2 or more psychotropic drugs than those living with family and relatively independently. Adults with ASD who had a history of aggression were 5 times as likely to be taking any psychotropic medication, and 2 times more likely to be taking 2 or more psychotropic medications than those without aggression history. Finally, adults with ASD who were receiving psychiatric services were 4 times more likely to be prescribed any psychotropic medication and 2 times more likely to be on 3 or more psychotropic drugs than those not seeing a psychiatrist.

Conclusions: Almost one half of the current sample was prescribed 2 or more psychotropic medications with antipsychotics being the most commonly prescribed psychotropic drug. Group home residence, psychiatric support and history of aggression were all risk factors for polypharmacy. As such, adults with ASD living in group homes or who have a history of aggressive behaviour may be at particular risk for polypharmacy. Knowledge of these patterns may help families, clinicians and individuals with ASD anticipate the use of medication, and explore strategies to best monitor medication use and consider alternative or adjunctive treatments.