Preservation of limbic and paralimbic structures in aging

The relatively young age of the cohort is important because the DLPFC undergoes accelerated GM loss during normal aging, so in a geriatric MDD cohort these changes may be attenuated relative to the normal population due to age-related changes common to both groups.

“The relatively young age of our cohort is also important since the DLPFC undergoes accelerated GM loss during “normal” aging (Grieve et al., 2005), so in a geriatric MDD cohort these changes may be attenuated relative to the normal population due to age-related changes common to both groups.”

Studies using ROI or VBM have yielded contradictory results regarding whether the hippocampus is preserved or deteriorates with aging.

“In spite of the objectivity of this method, studies led to somewhat contradictory results regarding the hippocampus: some authors have found this structure to be preserved with aging [29,31], whereas others have reported structural deterioration [38,81,84,87].”

The discrepancy in hippocampal findings may result from the samples selected, with preservation found when the sample covered a large life span and atrophy observed when age effects were evaluated within older samples.

“This discrepancy may result from the samples selected in these studies. Thus, preservation of the hippocampus was found when the sample covered a large life span (17-79 years in Good et al. [29] and 8-79 in Grieve et al. [31]), whereas atrophy was observed when age effects were evaluated within older samples, i.e. 50 or 60 years and over ([38,70,81, but see [84]).”

In normal adults, global brain atrophy is generally more pronounced in frontal areas, often followed by parietal, temporal and insular gray matter loss.

“Overall, the literature consistently reports global brain atrophy in normal adults, generally more pronounced in frontal areas (for a review, [63]), often followed by parietal, temporal and insular gray matter (GM) loss [1,2,29,31,70,81,87].”

Optimized VBM studies have systematically reported gray matter loss in the frontal lobe with aging, also affecting the insula, Heschl gyrus, anterior cingulate cortex, sensorimotor areas and cerebellum.

“Authors have systematically reported GM loss in the frontal lobe with aging [1,29,31,37,38,81,84,87], also affecting the insula, Heschl gyrus, anterior cingulate cortex, sensorimotor areas and cerebellum.”