A focus on valproate and cognitive deficits in Bipolar Disorders : a mini-review

BACKGROUND: Cognitive deficits represent a core feature of Bipolar Disorder (BD), which seem to characterize this disorder regardless of the mood phase. However, the role of pharmacological treatment in determining cognitive alterations is still not clear. Indeed, although drugs improve cognition by targeting mood symptoms, they could also carry their own cognitive side effects. This is true especially for mood stabilizers as they are the most commonly prescribed drugs in patients affected by BD and they are usually administered also during euthymic phases. METHODS: In this context, the present review aimed at summarizing the results of the studies evaluating the impact of valproate on cognitive functions in patients suffering from BD, as primary or secondary results. The inclusion criteria were met by ten studies. Specifically, we included one double-blind quasi-randomized study and nine cross-sectional or naturalistic studies, which a) used healthy subjects as control group (N = 1), b) compared valproate treated patients with healthy individuals and other treatments (N = 5), and c) compared valproate treated patients just with other treatments, with a specific focus on lithium (N = 3). RESULTS: Overall the results suggested a negative effect of valproate on cognitive functions in chronically-treated patients affected by BD. Notably, it has been found that the working memory was the most affected cognitive domain. LIMITATIONS: Few studies directly explored the effect of valproate on cognition in BD. CONCLUSIONS: These findings seem to suggest that valproate might have a negative effect on cognitive functions, especially on working memory domain. However, the results should be taken cautiously since the limited number of available studies published so far. In conclusion, these evidences seem to point out that the possible cognitive side effects of pharmacological treatments should be carefully taken into account, especially in chronic patients.