Long-Term Bipolar Treatment Maintains Cognitive Health

Cognitive impairment in patients with bipolar disorder is a growing research priority. Long suspected to be restricted to those with symptomatic illness, cognitive impairment has also been found in patients who are well controlled and euthymic.

Bipolar patients often experience cognitive impairments of various types throughout their lives, and they also are at elevated risk for mild cognitive impairment and dementia later on. In its latest online collection, the International Journal of Bipolar Disorders included a study that examined such issues as they relate to long-term lithium treatment.

Lithium has been the gold standard for long-term prophylactic treatment for bipolar disorder since the 1960s, mainly due to the drug’s ability to prevent new mood swings and reduce the frequency of harmful episodes. Cell culture and animal data have shown that lithium also offers neuroprotective effects by preventing programmed cell death and increasing neurotrophin excretion.

However, short- and long-term data on lithium’s neuroprotective effects in humans are scarce. Thus, a multinational team of researchers used data from the International Group for the Study of Lithium-Treated Patients to compare 3 groups of study subjects:

1. Bipolar patients with <3 months of exposure to lithium treatment (non-Li group, n=31) who received alternative mood stabilizers

2. Bipolar patients with ongoing lithium treatment for >24 months (Li group, n=58)

3. Healthy control subjects (n=53).

According to the authors, bipolar patients who had received long-term lithium treatment with any mood stabilizer were similar to controls on measures of cognitive functioning and verbal learning, recall, and recognition. Patients in the Li group had larger hippocampal volumes than non-Li subjects, but they were similar to healthy controls.

Compared with the control subjects, all bipolar patients—especially those in the Li group&mdash;exhibited inferior early visual information processing, indicating that their early learning was impaired. Nevertheless, the researchers suggested that effective phase prophylaxis with lithium or any mood stabilizer could reduce impairment in bipolar patients’ cognitive performance.

“Our data suggest that bipolar patients with a long illness history and effective prophylactic treatment do not show significantly impaired general cognitive functioning or verbal learning and memory, but that they do display worse early information processing,” the authors concluded.