The issue of persistent cognitive deficits in euthymia is of profound importance because of its potential as a trait marker for bipolar disorder. The residual neurocognitive dysfunction in euthymic patients with bipolar disorder raises the possibility of primary cognitive changes that are independent of mood state.Aim
This study aimed to ascertain whether patients with bipolar I disorder show different pattern and deficits in neuropsychological performance compared with well-matched apparently healthy controls.Patients and methods
Thirty euthymic bipolar I patients (Hamilton depression score<7 and Young mania scale<7) were recruited from the Institute of Psychiatry; they fulfilled the Diagnostic and Statistical Manual of Mental Disorders, 4th ed. criteria for bipolar I disorder. We compared them with 30 healthy controls for neurocognitive functions. We assessed them using the Wechsler Adult Intelligence Scale (WAIS), the Wechsler Memory Scale (WMS), the Continuous Performance Test (CPT), and the Wisconsin Card Sorting Test (WCST).Results
Patients with bipolar I scored significantly lower in the total and all subscales of both WAIS and WMS, almost in all domains of the tests than did the controls (P=0.000).Results
On the CPT, the control group had statistically significant fewer total commissions (P=0.000) and fewer total omissions (P=0.003) than did bipolar I patients. The patient group obtained worse scores compared with the controls in almost all the subtests of WCST.Conclusion
The present study highlighted that cognitive impairment persists in the euthymic phase of bipolar disorder, which may represent a trait variable independent of mood state.