The rate of reward center volume loss may vary between nondepressed individuals and depressed individuals across multiple age groups.
A recent study into striatal volumes in older patients with major depressive disorder (MDD) has uncovered an indication that deficits in the reward circuit may change with age and melancholic subtype.
The study, led by Natalie J. Sachs-Ericsson, PhD, from the Department of Psychology, Florida State University, Tallahassee, FL, was preceded by sparse research on striatal volume in older adults and depression subtypes. However, researchers noted growing evidence shows differences between those with and without MDD, and regions of the brain associated with reward sensitivity.
“Reward processing depends on the striatum of the basal ganglia, including the caudate nucleus and putamen, which have been implicated in the receipt and anticipation of reward,” researchers wrote.
Using data from the Neurocognitive Outcomes of Depression in the Elderly study, researchers delineated differences in putamen and caudate nucleus volumes in adults age 60 years and older, without dementia, from 1994 to 2011.
A group of 226 depressed participants was compared with a group of 134 healthy control participants. In addition, a group of 93 nonmelancholic depressed individuals was compared with a group of 133 melancholic depressed individuals. The study also accounted for group-by-age interactions.
In the left putamen, they determined that volume size was greater in the healthy control group’s left putamen when compared with those of the depressed group, but only among participants aged 60 to 65 years. Among the older participants, group differences were fewer.
No significant differences regarding the caudate nucleus were found, however.
In the groups of depression subtypes, the nonmelancholic group’s participants had larger left putamen volume than the melancholic group. The research team associated symptoms of anhedonia with smaller left and right putamen.
“Structural abnormalities in reward regions may underlie the anhedonic phenotype. Volume loss associated with MDD may attenuate in older age,” researchers noted. “The findings suggest that decreased volume in the putamen is associated with melancholic depression, and in particular, symptoms of anhedonia, in geriatric depressed patients.”
The rate of reward center volume loss may also vary between nondepressed individuals and depressed individuals across multiple age groups.
Researchers also indicated the result should be considered in light of evidence that late-life anhedonia is associated with a more serious course. Because the study was among the first to examine such issues in different subtypes of depression in elderly patients, the overall results should serve as a preliminary guide to future research.
“Further, we should note that although we examined age of onset of depression (early versus late) in relation to volume size—this measure is limited in regard to determining whether the individual had long-term or chronic depression over the lifetime,” researchers wrote.
The study, "Putamen Volume Differences Among Older Adults: Depression Status, Melancholia, and Age," was published online in the Journal of Geriatric Psychiatry and Neurology.
Related Coverage >>>