Middle-aged persons with subjective memory complaints have a thinner cortex in brain regions that are vulnerable to Alzheimer’s disease and perform worse on objective cognitive tests that suggest Alzheimer’s disease, compared with middle-aged persons without subjective memory complaints, according to research presented at the 2014 Alzheimer’s Association International Conference.
“These findings suggest that some persons who endorse subjective memory complaints in midlife might be at increased risk of progression to Alzheimer’s disease in the future,” reported Stephanie Schultz, a research specialist at the Wisconsin Alzheimer’s Disease Research Center in Madison. “Therefore, such individuals might be prime candidates for clinical trials aimed at retarding the evolution of the Alzheimer’s disease pathophysiologic process.”
Subjective memory complaints are subtle changes in memory that fall below detection thresholds of common cognitive tests. “However, it is not fully known whether persons with subjective memory complaints have Alzheimer’s disease–related brain alterations or whether they indeed demonstrate poorer cognitive performance,” noted Ms. Schultz.
The researchers sought to determine whether subjective memory complaints were associated with the thinning of cortical regions involved in Alzheimer’s disease and worse performance on objective cognitive tests. Analysis was based on 216 middle-aged persons with risk factors for Alzheimer’s disease who were enrolled in the Wisconsin Registry for Alzheimer’s Prevention (median age, 54; 67% women). Forty-two percent of subjects tested positive for APOE ε4, and 71% had a family history of Alzheimer’s disease.
All participants completed a questionnaire that included the following item pertaining to subjective memory difficulties: “Do you think you have a problem with your memory?” A total of 77 persons said “yes,” and 184 said “no.” During the same visit, the participants also underwent a comprehensive neuropsychologic examination. After a mean of 5.48 years, the subjects underwent a 3D T1 MRI scan.
The researchers observed no significant differences regarding age, sex, APOE ε4 status, family history of Alzheimer’s disease, education, or score on the Mini-Mental Status Examination between persons who reported subjective memory problems and those who did not.
Compared with those who did not report a subjective memory problem, persons with a subjective memory problem had “significant cortical thinning in the entorhinal, fusiform, posterior cingulate, and inferior parietal cortices, as well as significantly reduced amygdala volume,” stated Ms. Schultz.
In addition, compared with the group who did not report a subjective memory problem, the group with a subjective memory problem had “significantly lower test scores—albeit within normal limits—on measures of immediate memory, verbal learning and memory, and verbal ability,” Ms. Schultz concluded.
—Colby Stong