In 2007, Nunes and colleagues3 published a report of a cross-sectional study that examined lithium and the risk of Alzheimer disease in elderly patients (60 years and older) with bipolar disorder. The researchers found that the prevalence of dementia was lower in the patients who were receiving continuous lithium treatment than in those who were not.
Case registry studies have also found a lower risk of Alzheimer disease in bipolar patients after long-term lithium use, according to Gildengers. He described the work of Kessing and colleagues4 that linked registry data on prescribed lithium in all patients discharged from a psychiatric health care service with a diagnosis of mania or bipolar disorder and subsequent diagnoses of dementia. Continued treatment with lithium was associated with a reduced rate of dementia in patients with bipolar disorder in contrast to continued treatment with anticonvulsants, antidepressants, or antipsychotics.
Certainly, there is the concern that having bipolar disorder may increase the patient’s risk for dementia, but among individuals with bipolar disorder who took lithium continuously, their rate for having dementia returned to that of the general population, Gildengers said.
In their research, Nunes and colleagues found that among older patients with bipolar disorder, the prevalence of dementia was 19%—almost 3 times that expected in the elderly Brazilian population. But in their study, the prevalence of Alzheimer disease was increased only in patients who had not received recent continuous lithium treatment (33%). Conversely, the prevalence of Alzheimer disease in the continuous lithium group (5%) was similar to that reported in the elderly general population in Brazil.
Gildengers also presented preliminary data from his ongoing study of the effects of long-term lithium treatment in older adults with bipolar disorder. He and his colleagues are comparing patients with bipolar disorder (50 years or older) who have been taking lithium for 10 or more years with patients with bipolar disorder who had minimal or no exposure to lith-ium and also with mentally healthy controls matched for age, education, and medical burden.
Gildengers’ team has been studying older patients with bipolar disorder for the past decade and has been giving them repeated cognitive assessments and brain scans. The team is looking at cognitive function assessed across multiple domains (eg, language, memory, information processing speed, executive function, visuospatial ability, and attention) and at neuroimaging measures of brain health, specifically WMH burden, and fractional anisotropy (a measure of brain integrity). Comparing the patients with bipolar disor-der with controls, Gildengers’ team found that those with bipolar disorder have “much higher markers of inflammation,” lower total gray matter, and lower brain integrity values.
Gildengers said that those with bipolar disorder who have had lithium treatment for a decade or more have “significantly lower amounts of white matter hyperintensity burden than those with minimal or no exposure. They look like the controls.”
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