The impact of the trajectory of bipolar disorder on global cognitive function: A one-year clinical prospective case-control study.

BACKGROUND

The relationship between cognitive function and relapse of affective episodes in bipolar disorder (BD) is rarely studied. The aim of this prospective, longitudinal, case-control study was to assess the trajectory of cognitive function and mood occilations within a one-year period in patients with BD relative to healthy control (HC) individuals.

METHODS

The sample included 86 outpatients with BD in euthymia, and 44 gender-and-age-matched HC. All participants were evaluated with clinical assessement and neuropsychological testing at baseline and during euthymia after a year. Further patients with BD were reevaluated if they developed a new affective episode during follow-up. The patients´ affective states were recorded on a weekly basis as asymptomatic, subthreshold level, major depression or (hypo)mania. Cognitive changes over time were measured for a global cognitive score and for the four cognitive domains: 'working memory and executive skills', 'psychomotor speed', 'sustained attention', and 'verbal learning and memory' in patients and HC.

RESULTS

The study showed that cognitive performance in patients with BD was unaltered compared to baseline when they stabilised in euthymia following an affective episode and, at the one-year follow-up. Cognitive performance showed practice effect, thus improved within a year across patients with BD and HC. Furthermore, cognitive functions were not related to clinical subtypes BDI/II, prior psychosis, the polarity of the relapse and week-to-week mood fluctuations during follow-up. Functioning correlated weakly to moderately with week-to-week mood fluctuations.

LIMITATIONS: Modest sample size.

CONCLUSION

A one-year trajectory of BD seems to have no direct negative impact on cognitive function.