The purpose of the current study was to investigate the manifestation of ADHD in adults using a combination of structured clinical interview, behavioral self-report, and a range of neuropsychological measures. Symptom criteria that are endorsed by adults with ADHD as compared to non-diagnosed adults and an adult sample with other clinical disorders tend to reflect problems with follow-through, forgetting, organization, and losing things. Notably, adults in the No Diagnosis group endorsed a higher frequency of symptoms than base rates reported elsewhere. Related to sense of time, adults with ADHD endorsed problems with meeting deadlines, not completing tasks, not planning ahead, and having a poorer sense of time significantly more frequently than adults in either the No-Diagnosis or Other Clinical Disorder group. Results highlighted the need for further research specific to the manifestation of ADHD in adulthood and the development of diagnostic criteria that take into account the differences in development as well as age-related differences in contextual demands.
Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common disorders among children and adolescents; an estimated 3–7% of children are diagnosed with ADHD (American Psychiatric Association [APA], 1994, 2000; Barkley, 1998a). Historically, ADHD has comprised a constellation of behaviors that reflect attentional problems, poor impulse control, and motor activity or restlessness (APA, 1994). As a disorder, there is evidence to support a long-term developmental course for individuals with ADHD as well as familial patterns (National Institutes of Health Consensus Development Panel [NIH], 2000). There is general agreement that ADHD is a disorder that can be diagnosed reliably in children through the use of formal diagnostic criteria; however, these criteria were designed for and selected based on studies with children. Although ADHD is likely the most studied of the childhood psychopathologies (Barkley, 1998a), much less is known about ADHD in adulthood. Findings from studies with adolescents (e.g., Fischer, Barkley, Edelbrock, & Smallish, 1990; Seidman, Biederman, Faraone, Weber, & Ouellette, 1997) suggest that the neuropsychological deficits evident in children do not disappear over time. Of children identified as ADHD, the prevalence of continued manifestation of childhood symptoms is variable across studies and ranges from about 10% (e.g., Shaffer, 1994) to 79% (Weinstein, 1994) of individuals with ADHD.
Based on recent research, it is now estimated that 30–70% of those individuals diagnosed in childhood will continue to demonstrate significant distress in adolescence and adulthood (Barkley, Fischer, Edelbrock, & Smallish, 1990; Biederman et al., 1996; Gittelman, Mannuzza, Shenker, & Bonagura, 1985; Greenberg, 1994 and Hunt, 1997; Klein & Mannuzza, 1991; Mannuzza et al., 1991; Mannuzza, Klein, Bessler, Malloy, & Hynes, 1993; Spencer, Biederman, Wilens, & Faraone, 1998). The wide range is due at least in part to the variation in criteria used; differing criteria across research studies impede the ability to enhance diagnostic accuracy as well as our understanding of ADHD across the life span (Wolf & Wasserstein, 2001). No prevalence rate or base rate has been established for ADHD in adulthood due to the changes in conceptualization and diagnostic criteria; however, it has been estimated that the base rate in adulthood would be between 0.30 and 3.5% of the adult population (Barkley, 1998a; Heiligenstein, Guenther, Levy, Savino, & Fulwiler, 1999). Based on continued impairment of 30–70% of those diagnosed in childhood, and a childhood prevalence rate of 3–5%, it may be expected that the prevalence of ADHD among adults would be about 1–2% (Bellak & Black, 1992). When looking at the symptom set for ADHD with undergraduate students in the general population, men reported a mean of 0.95 (S.D. = 1.36) symptoms of inattention while women reported a mean of 0.75 (S.D. = 1.31). For the hyperactive/impulsive symptoms, means of 1.51 (S.D. = 1.53) and 1.52 (S.D. = 1.57) were reported for men and women, respectively (DuPaul et al., 200
