Neurocognitive profiles in bipolar I and bipolar II disorder: differences in pattern and magnitude of dysfunction.
OBJECTIVE
Studies on neurocognitive functioning in bipolar disorder, reporting deficits in memory, attention, and executive functioning, have primarily focused on bipolar I disorder. The aim of this study was to examine whether patients with bipolar I and bipolar II disorder have different neurocognitive profiles.


METHODS
Forty-two patients with bipolar I disorder, 31 patients with bipolar II and 124 healthy controls, from a large ongoing study on psychotic disorders, were included. Neurocognitive function was measured with a comprehensive neuropsychological test battery.


RESULTS
The bipolar I group performed significantly poorer than the healthy control group and the bipolar II group on all measures of memory. Compared with the control group, the bipolar I group also had significantly reduced performance on most measures of attention and executive functioning, while the bipolar II group only had a significantly reduced performance on a subset of these measures. On average, 24% of the bipolar I group had clinically significant cognitive impairment (< or =1.5 SD below the control group mean) across measures, compared with 13% of the bipolar II group.


CONCLUSIONS
Patients with bipolar I and bipolar II disorder in this study have different neurocognitive profiles. Bipolar I patients have more widespread cognitive dysfunction both in pattern and magnitude, and a higher proportion has clinically significant cognitive impairments compared with patients with bipolar II. This may suggest neurobiological differences between the two bipolar subgroups.
Simonsen
Carmen
C
Department of Psychiatry, Ulleval University Hospital, and Institute of Psychology, University of Oslo, Oslo, Norway. c.e.simonsen@medisin.uio.no
Sundet
Kjetil
K
Vaskinn
Anja
A
Birkenaes
Astrid B
AB
Engh
John A
JA
Hansen
Charlotte Fredslund
CF
Jónsdóttir
Halldóra
H
Ringen
Petter Andreas
PA
Opjordsmoen
Stein
S
Friis
Svein
S
Andreassen
Ole A
OA
D000328:Adult; D001288:Attention; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D001921:Brain / Q000503:physiopathology*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000453:epidemiology; D009483:Neuropsychological Tests; D015995:Prevalence; D012720:Severity of Illness Index; D014706:Verbal Learning