To our knowledge, this is the first study to report on late adolescent and young adult outcomes of girls diagnosed with ADHD in childhood. This study extends previous findings on impairment in adolescent females with ADHD (Hinshaw et al., 2006
; Biederman et al., 2006
), and explores domains relevant for late adolescents and young adults, including psychopathology, delinquency, interpersonal impairment, academic achievement, job performance, and substance use. Parent reports revealed more evidence of impairment for proband women than did self report alone.
The current study found some evidence of internalizing problems in proband females, consistent with other female ADHD studies (Biederman et al., 2008
; Hinshaw et al., 2006
). Forty-five percent of proband women (compared to only 26% of comparison women) had scores of 16 or higher (Beekman et al., 2002
), but the majority of the probands (55%) did not exhibit elevated levels of depression. Thus, only a subset of ADHD females appears to be at risk for depression in late adolescence and young adulthood. Parents of probands also indicated clinically impaired levels of self-esteem for women with ADHD, but there were no self-reported differences, which may be related to problems with self-perception often reported in individuals with ADHD (Owens et al., 2007
) discussed below.
Parents of ADHD females reported that their daughters experienced more ADHD symptoms than comparison females, and a small to moderate effect size was observed by self-report. However, the median of 3 ADHD symptoms endorsed by parents is lower than the 6 symptoms needed for diagnosis (APA, 2000
). Using symptom counts, only 41% of probands met DSM criteria in adulthood based on maternal report, and 12% of probands would have met criteria by self report. If a cut-off score of ADHD symptoms 1.5 standard deviations above the mean of the comparison sample was used to diagnose ADHD (cf. Barkley, Fischer, Smallish, Fletcher, 2002
), 57% of probands by parent report, and 23% by self report would have met diagnosis, compared to 5% by parent report and 8% by self-report in comparison females. The reduction in symptoms for proband females in late adolescence and young adulthood is consistent with developmental trends in ADHD diagnosis for boys into adulthood (Barkley et al., 2002
; Willoughby, 2003
), and the percentage of comparison women who meet criteria in late adolescence and young adulthood challenges the validity of ADHD diagnoses in adulthood.
Consistent with previous research, we found some evidence that proband females engage in more delinquency than comparison females (Biederman et al., 2006
; Molina et al., 2007
). However, the median level of offending reported by females with ADHD in this study is only moderate, (e.g. theft of approximately 5 dollars outside the home), and less severe than levels previously reported in males (e.g. Molina et al., 2007
). Over 9% of males within PALS engaged in serious levels of delinquency, which includes more than one instance of acts such as assault and murder (Sibley et al., in preparation), but no women endorsed such severe delinquency.
Parent and sibling relationships for probands appear to suffer, particularly as reported by parents. The findings of this study extend upon research on interpersonal difficulties in families affected by childhood ADHD (Peris & Hinshaw, 2003
; Pelham & Lang, 1999
), into young adulthood. It is not clear what proband behavior and parent-offspring interactions (e.g. mother-daughter) give rise to these negative evaluations. In childhood, noncompliance with parental requests and an impulsive, oppositional interpersonal style characterizes the social relationships of ADHD males and females (Pelham & Bender, 1982
). It is reasonable to speculate that the interpersonal style with a concomitant negative impact on relationship with others continues in females with ADHD. These negative interactions are likely exacerbated for women who continue to live at home. The greater conflict in relationships with mothers compared to fathers is consistent with research on young adult females (Laursen, Coy, & Collins, 1998
), however because the majority of parent report was from mothers, further research could clarify whether parent-child difficulties in ADHD women are specific to mothers or is a result of our methods
The impaired peer and romantic relationships experienced by proband females extend literature on interpersonal difficulties for females with ADHD (Barkley, 2006
; Blachman & Hinshaw, 2002
; Pelham & Bender, 1982
) into late adolescence and young adulthood. The same impulsive and oppositional interpersonal style speculated to affect females with ADHD’s parental relationships may also interfere in peer and romantic relationships. The absence of group differences in romantic relationships may be because measures were only administered to females (56% of probands and 79% of comparison) who were in relationships (and their parents). It is possible that the probands who are in romantic relationships are the females with the best interpersonal skills and provide an overestimation of ADHD women’s functioning in this domain.
The lower achievement and greater academic support and grade retention for probands in this study correspond with previous literature (Hinshaw et al., 2006
; Biederman et al., 2006
). It is notable that when IQ was controlled, differences in academic performance did not remain, suggesting that achievement deficits are not driven exclusively by ADHD (Neisser et al., 1996
). The nearly 15-point IQ difference between women with and without ADHD in this study is larger than the discrepancy reported for males with and without ADHD (Frazier, Demaree, & Youngstrom, 2004
). This finding, combined with the absence of school disciplinary problems, serves as evidence that academic difficulties for ADHD females are likely to be a function of general cognitive functioning (e.g. inattention, overall intelligence) rather than disruptive behavior, which may be an important cause of academic achievement problems in ADHD males. Females with ADHD may be more likely than males to be referred for treatment for learning problems (Gaub & Carlson, 1997
), rather than disruptive school behavior.
Consistent with research on occupational problems in males with ADHD (Barkley, 2006
), probands reported more disciplinary actions and parent rated impairment. However, the absence of group differences in occupational status and self reported job performance may be because approximately a third of the sample was 18 years old or younger, so even if the women were employed, they were in low-level part-time jobs in which they could function relatively well. Given the academic difficulties of young women with ADHD, females in the comparison group may be more likely than probands to pursue jobs that require higher education and skill when they move into the full time work force. Occupational differences may emerge later.
We did not find evidence of greater substance misuse in probands. The rates of alcohol, cigarette, and marijuana use were not higher than rates of comparison women, and reflect typical use patterns (SAMSHA, 2003). These null findings are likely related to the normative increased substance use in young adults, in general. In a sample of PALS males, adolescents (11 to 17 years old) reported more alcohol use compared to controls, but there were no group differences for young adult males (18 to 25 years old; Molina et al., 2007
). Substance misuse may become more salient in female ADHD samples as typically developing women engage in more professional activities, such as obtaining a job and home, marrying, and having children. Alternatively, in the context of impaired social relationships for probands, substance use may be low due to fewer social opportunities to engage in substance use and the fact that many women in both samples are still living with their parents. Substance use is an important domain to continue to study through the risk period for substance abuse to understand if the risk for alcohol and other drug use emerges at a later age.
A common thread throughout the results was that parents reported more impairment than their daughters with ADHD. This discrepancy extends previous research on reporting problems in children with ADHD (Barkley et al., 2002
; Smith et al., 2000
). Further support for problems in self-perception for late adolescent and young adult females with ADHD was found by considering the anchoring of the questions. When questions were asked to infer that women have problems (e.g. “have you experienced problems with alcohol?”) as opposed to questions that can be answered with objective statements (e.g. “how many beers do you typically consume in a week?”), proband women may be less likely to endorse the item. In this study, women reported fewer relationships and more work disciplinary actions, but when asked specifically about “problems,” group differences did not emerge.
Limitations and conclusions
The small sample size reduced power to detect statistically significant group differences. The use herein of unbiased nonparametric tests and reporting of effect sizes increases confidence that in a larger sample, larger group differences between proband and comparison women might emerge in several of the domains we assessed. In addition, clinic-referred females such as those in our study have been shown to display more severe impairment compared to community samples of females with ADHD (Gaub & Carlson, 1997
). Thus, the findings from this study may not generalize to all females with ADHD, and without comparing young adult female outcomes to the outcomes of males with ADHD, we are unable to determine whether there are gender-specific young adult outcomes of ADHD.
Almost the entire field of ADHD research has been developed from predominantly male samples. Consistent with previous research on females with ADHD (Biederman et al., 2006
; Hinshaw et al., 2006
), this study found evidence that female ADHD in late adolescence and young adulthood is a significant problem which persists into young adulthood for a substantial portion of females. The findings of the current study along with the growing literature on women self-identifying with ADHD in adulthood, highlight the importance of continued efforts to identify and understand ADHD in females.