Persistent cognitive dysfunctions in bipolar I disorder and schizophrenic patients: a 3-year follow-up study.
BACKGROUND
Neurocognitive impairment has consistently been considered a central and stable feature in schizophrenia. As this possibility has been far less studied in bipolar disorder, we aimed to prospectively investigate the stability and specificity of cognitive performance in bipolar disorder compared to schizophrenia.


METHODS
Fifteen DSM-IV bipolar type I patients and 15 schizophrenic patients were assessed twice with a comprehensive neuropsychological battery and the Positive and Negative Syndrome Scale over a 3-year follow-up. The cognitive performance of the groups was compared at baseline and 3 years later as a mean with that of 26 healthy volunteers. Endpoint and baseline assessments were also compared for each patient group in order to evaluate the stability of cognitive impairment.


RESULTS
At both time points, bipolar and schizophrenic patients showed significant deficits on most of the cognitive tasks compared to healthy subjects. Overall, the cross-sectional cognitive profile was similar for both patient groups. Moreover, after controlling for age and length of illness, the two groups' cognitive function did not differ over time in any test. With the exception of the Stroop color-word interference task, performance at baseline for each test but neither length of illness nor diagnostic category predicted the endpoint performance.


CONCLUSIONS
This preliminary study suggests that cognitive impairment is also mainly stable over time in bipolar I disorder and thus not specific to schizophrenia.
Balanzá-Martínez
Vicente
V
Psychiatry Service, University Hospital Doctor Peset, Valencia, Spain.
Tabarés-Seisdedos
Rafael
R
Selva-Vera
Gabriel
G
Martínez-Arán
Anabel
A
Torrent
Carla
C
Salazar-Fraile
José
J
Leal-Cercós
Carmen
C
Vieta
Eduard
E
Gómez-Beneyto
Manuel
M
D000328:Adult; D001714:Bipolar Disorder / Q000150:complications* / Q000523:psychology*; D003072:Cognition Disorders / Q000209:etiology* / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011379:Prognosis; D012559:Schizophrenia / Q000150:complications*; D013997:Time Factors