Neuropsychological correlates of emotional lability in children with ADHD
Background:
Emotional lability (EL) is commonly seen in patients with Attention
Deficit/Hyperactivity Disorder (ADHD). The reasons for this association are
currently unknown. To address this question we examined the relationship between
ADHD and EL symptoms, and performance on a range of neuropsychological tasks
to clarify whether EL symptoms are predicted by particular cognitive and/or
motivational dysfunctions and whether these associations are mediated by the
presence of ADHD symptoms.
Methods:
A large multi-site sample of 424 carefully diagnosed ADHD cases and 564
unaffected siblings and controls aged 6 to 18 years performed a broad
neuropsychological test battery, including a Go/No-Go Task, a warned 4-choice
Reaction Time task, the Maudsley Index of Childhood Delay Aversion, and Digit span
backwards. Neuropsychological variables were aggregated as indices of processing
speed, response variability, executive functions, choice impulsivity and the influence
of energetic and/or motivational factors.
EL and ADHD symptoms were regressed on each neuropsychological variable in
separate analyses controlling for age, gender and IQ, and, in subsequent regression
analyses, for ADHD and EL symptoms respectively.
Results:
Neuropsychological variables significantly predicted ADHD and EL
symptoms with moderate to low regression coefficients. However, the association
between neuropsychological parameters on EL disappeared entirely when the effect
of ADHD symptoms was taken into account, revealing that the association between
the neuropsychological performance measures and EL is completely mediated
statistically by variations in ADHD symptoms. Conversely, neuropsychological
effects on ADHD symptoms remained after EL symptom severity was taken into
account.
Conclusions:
The neuropsychological parameters examined here predict ADHD
more strongly than EL. They cannot explain EL symptoms beyond what is already
accounted for by ADHD symptom severity. The association between EL and ADHD
cannot be explained by these cognitive or motivational deficits. Alternative
mechanisms, including overlapping genetic influences (pleiotropic effects), and/or
alternative neuropsychological processes need to be considered.