Brain region volume differences in elderly patients with late- and early onset mania
MedWire News: Results from a Taiwanese study show that late-onset mania is associated with volumetric differences in specific brain regions compared with early-onset mania in elderly patients with bipolar disorder.
"An increasing number of neuroimaging studies of bipolar disorder show significant volumetric alteration in various areas of the brain, including the striatum, frontal lobe, orbitofrontal cortex, amygdala, anterior cingulate gyrus, dorsolateral prefrontal cortex, temporal lobe, and thalamus," explain Shang-Ying Tsai (Taipei Medical University) and team.
However, they add that few studies have investigated such changes in elderly patients with bipolar disorder, particularly with respect to late-onset mania, which "is associated with increased cerebrovascular morbidity and neurological damage compared with typical/early-onset mania."
To address this, the researchers studied 44 patients with bipolar disorder who were older than 60 years of age. Of these, 25 patients had early-onset and 19 had late-onset mania, with a cutoff age of 45 years defining the two groups.
Patients in both groups, who were similar in terms of demographic variables, and had comparable cognitive function, body mass indexes, psychosocial functioning, and clinical course (total number of episodes), underwent volumetric magnetic resonance imaging of the brain. The volume of each cortical region was measured as a percentage of the total intracranial volume.
The researchers found that, overall, left caudate nucleus and left middle frontal gyrus volumes were significantly greater in late- than early-onset patients, at 0.2611% versus 0.2591%, and 0.7864% versus 0.7045%. respectively. In contrast, mean right posterior cingulate gyrus volume was significantly smaller in late- than early-onset patients, at 0.0744% versus 0.0798%.
There was no statistically significant difference in mean total intracranial volume (1194.5 vs 1238.3 ml) or total volume of gray and white matter (913.7 vs 879.8 ml) between the late- and early-onset patients.
However, the researchers note that comorbid cerebrovascular disease was more common in late-than early-onset patients, at 26.3% versus 4.2%.
"The results of this study suggest that reduced volume of the right posterior cingulate gyrus is closely associated with late-onset mania and that reduced volume of the left caudate nucleus and left middle frontal gyrus is associated with early-onset mania," Tsai and team conclude.
The research is published in the journal International Psychogeriatrics.
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By Mark Cowen