Results of a new study showed that girls with a childhood diagnosis of attention-deficit hyperactivity disorder (ADHD) are more likely to report increased ADHD symptoms as adults. This finding was not present in boys.
The study, led by Sabina Millenet, Dipl.-Psych, Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany, was published in the journal European Child & Adolescent Psychiatry.
Although ADHD is primarily thought of as a childhood or adolescent disorder, prior studies have shown up to 70% of patients diagnosed as children still show symptoms into adulthood. However, one recent prospective, representative longitudinal study identified only 5% of participants with persistent symptoms. This large discrepancy is thought to be due to self-reporting of symptoms, which can result in significant bias.
Age is another obstacle when analyzing inconsistencies in the ADHD literature. Younger children tend to have difficulty self-judging their behaviors, which can lead to differences between self-reported symptoms and symptoms reported by their parents. Parent-reported symptoms have been shown to have higher agreement with objective neurophysiological markers than self-reported symptoms.
As the child ages, the transition from a measurement scale consisting of parent-reported symptoms to one with self-reported symptoms can cause further inconsistencies.
In this study, researchers sought to clarify the sex-specific differences in self-reported symptoms in young adults with and without a diagnosis of childhood ADHD.
They investigated the effects of a childhood ADHD diagnosis on parent-reported adolescent ADHD symptoms, the congruence of self- and parent-rated symptoms, and the trajectories of self-reported ADHD symptoms from adolescence to young adulthood. The study also examined sex-specific prediction of self- and parent-reported symptoms.
As part of the data analysis, post hoc contrasts were used to compare the sex by childhood ADHD diagnosis groups with respect to congruence with parent-reported ADHD symptoms; parent-reported ADHD ratings were given by mean and mean plus or minus one standard deviation.
Data came from participants in the Mannheim Study of Children at Risk, which includes outcomes from early risk factors from infancy to adulthood. Almost 400 children born between 1986 and 1988 in the Rhine-Neckar region of Germany were enrolled. After eliminating participants who dropped out or who were excluded, the final sample included 336 patients (male, 161; female, 175).
A Diagnostic and Statistical Manual of Mental Disorders-oriented ADHD scale constructed from the Child Behavior Checklist and the Youth Self-Report was used to obtain comparable ratings over the length of the study. The two questionnaires are widely used to assess various problems in children aged 4 to 18 years.
Results showed that 47 participants (14%) were diagnosed with ADHD at least once before the age of 11. More boys than girls received an ADHD diagnosis (ratio: 2.1:1), but boys and girls diagnosed with ADHD did not have significant differences regarding inattention and hyperactivity/impulsivity at 15 years of age.
Parent-reported scores were significantly higher in children at 15 years of age who had received a childhood ADHD diagnosis between the ages of 4.5 and 11 years. The parental ratings did not differ by the sex of the child.
After analyzing the congruence between parent- and self-reporting at age 15, an interaction between sex and childhood ADHD diagnosis was noted. Post hoc testing revealed female adolescents with childhood ADHD whose parent’s reporting was rated at the mean showed significantly less congruent self-rating scores than female adolescents without a childhood ADHD diagnosis.
Adolescent girls with a childhood ADHD diagnosis were shown to over-report their ADHD symptoms more often than others in the study. In addition, parent ratings at the mean minus one standard deviation showed a similar result. Adolescent boys with and without a childhood ADHD diagnosis did not differ at the three values of parent ratings.
There was a significant moderation of the effect of a childhood ADHD diagnosis by sex from the baseline at age 15 through age 25. Females with a childhood ADHD diagnosis had significantly higher self-rated scores than males at ages 15 and 25. Females with childhood ADHD also had significantly more self-rated symptoms at age 15 than those without a childhood diagnosis; this difference persisted into young adulthood. Males showed no significant effect, either at age 15 or at age 25.
In female adults, the presence of childhood ADHD—but not internalizing disorders—significantly predicted self-reported ADHD symptoms at age 25. Once again, this was not seen in males.
The authors note that self-reported ADHD symptoms have been shown to have less informative value than ratings reported by parents. In addition, girls with a childhood ADHD diagnosis but normal parent-rated scores tended to self-report worse scores.
One theory posits that since research has shown girls with ADHD report more relationship impairments and lower self-esteem than boys do, the resulting negative self-image may persist into adolescence and adulthood, even if ADHD symptoms are no longer present.
“From our prospective longitudinal study, it can be concluded that self-reports of young adults with a childhood diagnosis of ADHD are influenced by sex,” the authors wrote. “In particular, in contrast to females, males with childhood ADHD did not report enhanced levels of symptoms either in adolescence or in young adulthood.”
They explained that other sources of information in addition to self-reports are valuable in the measurement of ADHD symptoms and the level of impairment. For long-term ADHD outcomes, a sex-specific perspective is important.
To read more about this study, click here.