Case-control study of neurocognitive function in euthymic patients with bipolar disorder: an association with mania.
BACKGROUND
Neurocognitive impairments in euthymic patients with bipolar disorder may represent trait rather than state variables.


AIMS
To test the hypothesis that euthymic patients with bipolar disorder would exhibit impairment in verbal learning and memory and executive function compared with healthy controls matched for age, gender and premorbid IQ.


METHOD
Twenty euthymic patients with bipolar disorder were matched, on a case-by-case basis, to twenty healthy community controls. Cases and controls were tested with a battery of neuropsychological tests.


RESULTS
Impairments were found in cases compared with controls in tests of verbal learning and memory. Verbal learning and memory correlated negatively with the number of manic episodes.


CONCLUSIONS
Impaired verbal learning and memory may be a trait variable in bipolar disease. There are implications for adherence to medication and relapse and for the role of early treatment interventions. Prospective designs and targeting first-episode groups may help to differentiate trait v. disease process effects.