Mood stabilizers and cognitive functions

Mood stabilizers are widely used for various indications particularly for bipolar disorders. For instance, lithium is an option in resistant depression cases, whereas valproate is used in impulse control disorders. Generally speaking, lithium and some anticonvulsants, such as valproate, carbamazepine, lamotrigine, and oxcarbazepine are members of mood stabilizers. In addition, off-label use of topiramate and gabapentin is also possible for same indications. Currently, mood stabilizers are the most accepted treatment for bipolar disorders. Among psychiatric problems, bipolar disorders are the second most leading cause of functional loss in social, academic and occupational fields; following schizophrenia spectrum disorders, therefore one may say that mood stabilizers are worth to mention. Bipolar disorders particularly when in depressive or manic state lead to cognitive impairments. In previous studies, it has been reported that impairment in cognitive functions are observed not only in disorder, but also in euthymic state (1). It is also known that besides the natural course of the disorders, Mood stabilizers are also associated with cognitive impairments. On the other hand, it is reported to be uncertain in some studies whether the cognitive functional performances of the bipolar cases are associated with mood stabilizer drugs (1). In some studies, lithium was reported to be associated with low processing speed and verbal memory performance (2), whereas in some studies no significant correlations were found between verbal memory processing speed and lithium as well as the other mood stabilizers (3). It is commonly accepted that valproate and carbamazepine are more likely to cause impaired cognitive functions in comparison with the other mood stabilizers. One may say that lamotrigine is the most tolerable one among mood stabilizers for cognitive functions. Despite all these considerations, mood stabilizers are less likely to have negative effects on cognitive functions when compared with anti-psychotics or benzodiazepines (1). In conclusion, it is accepted that the cognitive functions are impaired in bipolar disorders both endophenotypically and clinically. The overlapping results of the disorders themselves and the mood stabilizers in terms of cognitive functional impairment must be enlightened.