Background. Despite markedly different clinical presentations, few studies have reported differences
in neuropsychological functioning between mania and depression. The disinhibited behaviour
characteristic of mania and evidence that subgenual prefrontal cortex is differentially activated in
mania and depression both suggest that dissociable deficits will emerge on tasks that require
inhibitory control and are subserved by ventromedial prefrontal cortex.Methods. Manic patients and controls undertook computerized neuropsychological tests of
memory and planning ability. In addition, manic and depressed patients were directly compared
with controls on a novel affective shifting task that requires inhibitory control over different
components of cognitive and emotional processing.Results. Manic patients were impaired on tests of memory and planning. Importantly, affective
shifting performance of manic patients differed from that of depressed patients. Manic patients were
impaired in their ability to inhibit behavioural responses and focus attention, but depressed patients
were impaired in their ability to shift the focus of attention. Depressed patients exhibited an affective
bias for negative stimuli, and we believe this to be the first demonstration of an affective bias for
positive stimuli in manic patients.Conclusions. Observed impairments on tests of memory and planning suggest a global pathology
for mania consistent with previous profiles for this disorder and similar to established profiles for
depression. The results on the affective shifting task demonstrate the presence of mood-congruent
bias and dissociable components of inhibitory control in mania and depression. Against a
background of memory and planning impairments in the two groups, these findings are consistent
with a role for the ventromedial prefrontal cortex in mediating mood–cognition relationships.