Neurocognitive Function in the Euthymic Bipolar I Disorders

Cho, Hyun Sang; Lee, Sang Min; Soh, Hyung Suk; Song, Jin Kwan; Kim, Ji Hye; Jung, Hae Jung; Lee, Choong Heon; An, Suk Kyoon

Abstract

OBJECTIVES
The previous assumption that patients with bipolar I disorder make a full recovery of cognitive function in the euthymic phase has been challenged by studies that suggest neuronal changes, and recently persisting neuropsychological dysfunctions beyond episodes of the illness. The aim of the present study was to investigate the impairment of the neurocognitive performance of euthymic bipolar patients, the characteristics of cognitive impairment, and the relationship between cognitive dysfunction and clinical variables of illness in bipolar population.
METHODS
19 bipolar out-patients who had been euthymic for more than 3 months by Hamilton Depression Scale score below 7 and Young Mania Rating Scale score below 6 were compared with age- and education- matched 19 healthy subjects on neurocognitive tests. Patients showing observable extrapyramidal symptoms were excluded with the objective rating. The following tests were administered in according to cognitive domain: Korean-Wechsler Adult Intelligence Scale, subtests among Wechsler Memory Scale-Revised, Wisconsin Card Sorting Test, and Signal Detection/Decision-Reaction Timer/Psychomotor Performances among Vienna Test System.
RESULTS
The bipolar group performed significantly lower than the control group on verbal and performance IQ, total IQ, and psychomotor function or coordination. There was no relationship between the cognitive impairment and clinical course of illness, except duration of neuroleptic exposure.
CONCLUSIONS
Although our findings did not replicate the recently reported results, especially in the domain of executive function and verbal memory, they suggested the presence of neurocognitive difficulties, in the general ability and visuomotor function in stable bipolar patients. Also, we tailed to identify the influence of clinical course variables on cognitive area with statistically signficant differences.