Individuals with autism spectrum disorders (ASD) have persistent impairments across the life course and therefore have an ongoing need for services and treatment, often including medications (Aman, Lam, Van Bourgondien, 2005
; Martin, Scahill, Klin & Volkmar, 1999
). Only one medication, risperidone, has been approved by the Food and Drug Administration specifically for use among individuals with ASD who have serious behavior problems (Scahill, Koenig, Carroll & Pachler, 2007
) and there are few clinical studies addressing the effectiveness of medications in this population (Matson & Dempsey, 2008
). There is a limited, but growing, body of research on psychotropic medications used by individuals with ASD. Traditionally, most trials in the population have been open label (Matson & Dempsey, 2008
), although controlled trials are becoming more common (Myers, 2007
). Whereas advances have been made in pharmacological management of children with ASD (RUPP, 2002
), less is known about medication treatment for adolescents and adults with this diagnosis (Broadstock, Doughty & Eggleston, 2007
). Similarly, although there are several studies of medication prevalence in children and adolescents with ASD (Aman, Lam & Collier-Crespin, 2003
; Aman, Van Bourgondien, Wolford & Sarphare, 1995
; Langworthy-Lam, Aman & Van Bourgondien, 2002
; Witwer & Lecavalier, 2005
), less is known about the prevalence of medication during adolescence and especially adulthood in this population, which is the focus of the present study.
The prevalence of prescription medications for children with ASD is high. Surveys indicate that one-half to two-thirds are prescribed at least one medication of any type, and about 45% are prescribed at least one psychotropic medication (Aman et al., 2005
; Witwer & Lecavalier, 2005
). The most commonly prescribed psychotropic medications are antidepressants, stimulants, and antipsychotics (Langworthy-Lam et al., 2002
; Martin et al., 1999
). However, non-psychotropic medications are also prescribed at high rates for individuals with ASD, although few studies have been conducted to benchmark the prevalence of medications to treat physical health symptoms in this population. One exception to this gap in data about medication for physical health symptoms concerns anticonvulsant medication. The reported prevalence of anticonvulsant medication is approximately 5% among children with ASD (Witwer & Lecavalier, 2005
) and 11-13% among individuals across the life course (Aman et al., 2005
There is evidence that psychotropic medications are currently more frequently prescribed for individuals with ASD than they were in the past. Separate cross-sectional analyses of medication data collected from members of the North Carolina Autism Society in 1993 and 2001 suggested a 48% increase in psychotropic medication use during this eight-year period (Aman et al., 2005
). A higher prevalence of antipsychotic medications, antidepressants, psychostimulants, and alpha agonists and beta blockers was observed in 2001 than 1993, whereas a lower prevalence of hypnotics and anxiolytics was observed in 2001. There was no difference in the prevalence of other psychotropic medications such as mood stabilizers and opiate blockers between 1993 and 2001. During this same time period, the use of non-psychotropic medications, such as anticonvulsants, did not significantly change, although differences were observed in the types of anticonvulsants used (Aman et al., 2005
Prescription practices among individuals with ASD are influenced by the complex relationship between behavior problems and psychopathology (Brereton, Tonge & Einfeld, 2006
; Tsakanikos, Costello, Holt, Sturmey & Bouras, 2007
). Among individuals with ASD, the symptoms of autism and behavior problems change with age (Fecteau, Mottron, Berthiaume & Burack, 2003
; Mawhood, Howlin & Rutter, 2000
; Seltzer, Krauss, Shattuck, Orsmond, Swe & Lord, 2003
; Shattuck et al., 2007
), which potentially leads to differences in the medications that are prescribed at different life stages. Thus, there is a need to understand the prevalence and patterns of medication use among adolescents and adults with ASD and how these may change with age.
However, the literature on change in medication use by individuals with ASD suffers from two methodological limitations. First, repeated cross-sectional designs have been used to investigate both changes
in medication use over time and age-related differences
in medication use. Such designs can be affected by changes in prescription practices, not just the maturation and aging of the population of individuals with ASD. For example, atypical antipsychotics and SSRIs were developed in the 1990s and rapidly grew in popularity. Further, the use of risperidone among children with ASD has grown dramatically as a result of research demonstrating its effectiveness in treating tantrums, aggression and self-injury (RUPP, 2002
). Repeated cross-sectional studies are useful measures of general prescription practices but are neither informative of within-individual medication change, nor of differences in medication practices for children as compared to adults with ASD.
A second limitation of past research is that it has primarily focused on the use of psychotropic medications for individuals with ASD, with less investigation of the use of medications for other conditions in this population. Given the prevalence of comorbid physical health symptoms in individuals with ASD (e.g., seizures, gastrointestinal symptoms), additional research is warranted.
The present longitudinal analysis is unique because it examines changes in medication use over a period of 4.5 years in a community sample of individuals with ASD ranging in age from 10 to 48 years at the start of the study. For this analysis, we addressed two research questions. First, we asked whether medication use changes over time for adolescents and adults with ASD. We examined change using both measures of the proportion of individuals taking medication and the number of medications taken. Further, we examined if changes over time are different among adolescents as compared to adults with ASD. Second, we determined the odds of starting or stopping medication over the study period. For both of our aims, we examined psychotropic medications in separate analyses from non-psychotropic medications.