Cortical Thinning in Alzheimer Disease Tied to Neighborhood-Level Disadvantage

Neighborhood-level disadvantage is associated with cortical thinning in Alzheimer disease (AD) and cognitive decline as measured by the revised Preclinical Alzheimer disease Cognitive Composite (PACC-R) test, according to study results published in Neurology.

Study researchers derived data from neuroimaging substudies of the Wisconsin Registry for Alzheimer Prevention (WRAP) and the Wisconsin Alzheimer Disease Research Center clinical cohort longitudinal studies. They recruited participants in these studies from the community or from referrals from memory clinics. Participants did not have major psychiatric, neurological, or other illnesses that were likely to interfere with partaking in the study.

To measure neighborhood disadvantage, study researchers used the Area Deprivation Index for 601 participants’ latest residential address and compared it with the rest of their state. They collected magnetic resonance images (MRI) from each participant to estimate cortical thickness and its change between baseline and follow-up. They then calculated the per-year change rate of thickness in AD signature meta-ROI to quantify neurodegeneration.

 Additionally, the researchers calculated the participants’ score on the PACC-R, which included the Rey Auditory Verbal Learning Test learning trials (RAVLT-L); the Trails-Making Test, Part B (TMT-B); and a story memory delayed recall score (SM-D).

Findings indicated a significant association between high neighborhood-level disadvantage and faster decline in cortical thickness in AD signature regions, which remained significant when they controlled for participants’ racial and demographic differences. Living in highly disadvantaged neighborhoods was associated with significantly lower baseline scores on PACC-R and longitudinal decline on the tests (-0.67 [standard deviation, 0.13], P <.001).

Limitations of the study included the fact that a small portion of the participants in the longitudinal cohort lived in the 20% most disadvantaged neighborhoods, and the treatment of sex as a binary variable. Additionally, participants were predominantly nonHispanic, White and highly educated.

Based on their findings, the study researchers concluded, “The longitudinal structural degeneration and cognitive decline observed in individuals from the most disadvantaged neighborhoods suggests that increased clinical vigilance for early signs of dementia may be particularly important in this vulnerable population.”

Reference

Hunt JFV, Vogt NM, Jonaitis EM, et al. Association of neighborhood context, cognitive decline, and cortical change in an unimpaired cohort. Neurol. Published online April 14, 2021. doi:10.1212/WNL.0000000000011918