Regular treatment with lithium may reduce the risk of dementia in people with bipolar disorder, according to scientists who analyzed data from more than 40,000 adults. The study, published January 22nd in the British Journal of Psychiatry, examined records of patients over 50 diagnosed with bipolar disorder. For those who took lithium more than 300 days during the prior year, dementia occurred less frequently than for those who took the drug less frequently or not at all during the same period. Using lithium sporadically or intermittently did not affect the incidence of dementia, nor did treatment with anticonvulsants, no matter how often they were used.
Tobias Gerhard, Ph.D., of Rutgers University, used his 2010 NARSAD Young Investigator grant award to conduct the study. His team included Davangere Devanand, M.D., a recipient of Independent Investigator and Young Investigator grants in 1997 and 1987, respectively, and Mark Olfson, M.D., a 2005 NARSAD Distinguished Investigator grantee.
Lithium is an effective mood stabilizer for people with bipolar disorder. It was approved by the U. S. Food and Drug Administration in the 1970s, but its use has declined in the last 20 years as alternative treatments, such as the anticonvulsants valproic acid (Depakote and others) and lamotrigine (Lamictal), have become available.
Lithium blocks an enzyme called glycogen synthase kinase 3 (GSK3), which is known to contribute to Alzheimer's disease. For that reason, scientists have suspected that the drug might protect broadly against neurodegeneration, but clinical evidence has been inconsistent. The Gerhard team's analysis is the largest to date of dementia among people taking lithium to treat bipolar disorder.
The researchers used Medicare and Medicaid insurance claims data of people in eight states, from 2001 to 2004. For each of the patient records, the scientists analyzed lithium and anticonvulsant use as well as dementia diagnoses over the course of follow-up. Within the group, 6,900 patients used lithium, and 20,748 used anticonvulsants. During the study period, 1,538 patients were newly diagnosed with dementia.
Patients with bipolar disorder are thought to be more likely to develop dementia than patients without the disorder. The new study contributes to the evidence that consistent treatment with lithium––and not anticonvulsants––may reduce this risk. According to Dr. Gerhard, the findings “strengthen the hypothesis that lithium exerts a protective effect on the development of dementia in patients with bipolar disorder, and support clinical trials to further investigate the neuroprotective effects of lithium.”