Anti-Alzheimer’s Drug Memantine (Namenda) Has Positive Effects On Cognitive Dysfunction In Patients With Bipolar Disorder
Many patients with bipolar disorder experience cognitive dysfunction, but few treatments are available for this aspect of the illness. In an abstract presented at the 67th Annual Meeting of the Society of Biological Psychiatry in 2012, Dan V. Iosifescu reported that in a randomized 12-week study in which the anti-Alzheimer’s drug memantine was given to 72 euthymic bipolar subjects experiencing cognitive deficits, the drug was associated with improvement in spatial and working memory, verbal and episodic memory, and other indices that included measurements of attention and language skills. In conjunction with this treatment, a subgroup of subjects had increases in left hippocampal NAA (a measure of neuronal viability) and increases in choline in the right hippocampus. The initial improvements in these neuropsychological test results remained over 12 weeks of open follow-up.
Editor’s Note: These data are of considerable importance. Many studies indicate that the severity of the cognitive dysfunction patients experience while euthymic varies directly as a function of the number of prior episodes of mania or depression they have experienced. The degree of cognitive dysfunction in patients with bipolar disorder is also correlated with disability in social and economic functioning. Thus, the data that memantine can lead to improvement in several types of memory tests suggest that the drug could be useful in treating these deficits in some patients with bipolar disorder.
Memantine acts in part by blocking glutamate NMDA receptors and provides a different mechanism of action compared to the other drugs used to treat Alzheimer’s, which increase acetylcholine by blocking acetylcholinesterase.
Memantine has also shown promising effects in enhancing the antidepressant effects of lamotrigine, a drug that inhibits glutamate release. Thus, the similar target of action by which lamotrigine (blocking glutatmate release) and memantine (blocking glutamate receptors) operate suggest that the two drugs used in conjunction might produce additive effects in decreasing glutamate function. The current data suggest that memantine compared to placebo as an add-on to other agents in euthymic bipolar patients improves several measures of cognition as well.
New data published by Koukopoulos in the Journal of Affective Disorders in 2012 suggest that memantine (10-30mg/day) is an effective add-on treatment in severely ill patients with treatment-resistant bipolar disorder. Among those in Koukopoulos’ study, 72.5% were much or very much improved, thus there is a strong rationale for considering this drug.
