Impaired cognitive function among bipolar disorder patients seems to be stable over time, suggesting it is an enduring feature of the condition, show the results of a longitudinal study.
Levkovitz Yechiel (Shalvata Mental Health Care Center Hod-Hasharon) and colleagues say: "This stability is further emphasized by the relative lack of effect that acute depressive/manic episodes had on the cognitive functioning of the bipolar disorder patients."
Writing in Psychiatry Research, the team adds: "Specifically, no difference was found in the cognitive trajectory of bipolar disorder patients who relapsed and those that did not relapse during the follow-up period. Also, no change was evident in the patients' cognitive functioning despite a significant increase in the patients' manic symptoms."
The team recruited 31 asymptomatic and mildly symptomatic patients with bipolar disorder and 31 gender- and age-matched mentally healthy controls. Alongside a clinical interview, demographic, clinical, and pharmacological data were gathered, and all participants were administered a series of tests to examine visual-spatial memory and executive functions. These were repeated at a 2-year follow-up assessment.
Compared with healthy controls, bipolar disorder patients had significant deficits in psychomotor speed, sustained attention, and cognitive planning, and took longer to solve subsequent problems within a task. Patients also had a reduction in the percentage of correct responses on a spatial recognition memory task, although this did not reach significance.
At follow-up, the team found that bipolar disorder patients had significantly higher Young Mania Rating Scale (YMRS) scores versus baseline. However, there were no significant differences in the cognitive functioning of bipolar disorder patients between baseline and follow-up, and no evidence of cognitive decline.
The researchers also report that 15 patients relapsed during follow up. Compared with patients who did not relapse, these individuals were less educated and more likely to be single or divorced. Patients who relapsed also had more psychiatric hospitalizations, were more likely to have carried out a suicide attempt prior to baseline, and were more likely to be hospitalized during follow up.
YMRS scores were also higher among patients who relapsed than in those who did not. There were only minor cognitive differences between those who did and did not relapse.
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