Working memory – not processing speed – mediates fluid intelligence deficits associated with attention deficit/hyperactivity disorder symptoms
Article first published online: 31 DEC 2015
DOI: 10.1111/jnp.12096
© 2015 The British Psychological Society
Issue
Journal of Neuropsychology
Keywords:
- attention deficit/hyperactivity disorder;
- fluid intelligence;
- working memory;
- processing speed
Abstract
Attention
deficit/hyperactivity disorder (ADHD) is a psychological condition
characterized by inattention and hyperactivity. Cognitive deficits are
commonly observed in ADHD patients, including impaired working memory,
processing speed, and fluid intelligence, the three of which are
theorized to be closely associated with one another. In this study, we
aimed to determine if decreased fluid intelligence was associated with
ADHD, and was mediated by deficits in working memory and processing
speed. This study tested 142 young adults from the general population on
a range of working memory, processing speed, and fluid intelligence
tasks, and an ADHD self-report symptoms questionnaire. Results showed
that total and hyperactive ADHD symptoms correlated significantly and
negatively with fluid intelligence, but this association was fully
mediated by working memory. However, inattentive symptoms were not
associated with fluid intelligence. Additionally, processing speed was
not associated with ADHD symptoms at all, and was not uniquely
predictive of fluid intelligence. The results provide implications for
working memory training programs for ADHD patients, and highlight
potential differences between the neuropsychological profiles of ADHD
subtypes.
