Neurocognitive function in clinically stable men with bipolar I disorder or schizophrenia and normal control subjects.
BACKGROUND
Patients with bipolar disorder and schizophrenia have been shown to have neurocognitive deficits when compared with control subjects. The degree and pattern of impairment between psychiatric groups have rarely been compared, especially when subjects are psychiatrically stable.


METHODS
Using a standard neurocognitive battery, we compared euthymic outpatients with bipolar disorder (n = 40), stable patients with schizophrenia (n = 20), and subjects with no psychiatric disorder (n = 22). The neurocognitive domains assessed included executive functioning, verbal memory, visual memory, procedural learning, visuoconstructive ability, and language functions. Effect sizes were calculated for each cognitive domain across groups.


RESULTS
Stable schizophrenic subjects demonstrated a generalized cognitive impairment across most domains compared with control subjects, with average effect sizes of .9. Euthymic bipolar subjects were significantly impaired compared with control subjects only in executive functioning (Wisconsin Card Sorting Task) and verbal memory (California Verbal Learning Test) domains (effect sizes in the .8-.9 range). Performance on the executive function measures was bimodal among bipolar subjects, suggesting two subgroups: one with relatively normal and one with impaired executive functioning. No significant differences between the bipolar patient group and control subjects were observed in visuoconstructive ability, procedural learning, or language function.


CONCLUSIONS
Both euthymic bipolar subjects and relatively stable schizophrenic subjects differed from control subjects in neurocognitive function. Among schizophrenic subjects, a generalized cognitive impairment was observed, and the degree of impairment was greater in the schizophrenic compared with the bipolar subjects. Subjects with bipolar disorder were impaired in two specific domains (verbal memory and executive function). Furthermore, within the bipolar group there was a subset with relatively normal executive functioning and a subset with significant impairment. Possible reasons for the persistence of these neurocognitive deficits in some subjects with bipolar disorder during periods of euthymia are reviewed.
Department of Psychiatry and Biobehavioral Sciences, University of California-Los Angeles, Los Angeles, California, USA. laltshuler@mednet.ucla.edu
Lori L
LL
Altshuler
Joseph
J
Ventura
Wilfred G
WG
van Gorp
Michael F
MF
Green
David C
DC
Theberge
Jim
J
Mintz
D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001714:Bipolar Disorder / Q000188:drug therapy / Q000503:physiopathology*; D016022:Case-Control Studies; D003071:Cognition / Q000187:drug effects / Q000502:physiology*; D003710:Demography; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011340:Problem Solving / Q000502:physiology; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000188:drug therapy / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D014705:Verbal Behavior / Q000502:physiology
D014150:Antipsychotic Agents