Format of Original
Cambridge University Press
Journal of the International Neuropsychological Society
Original Item ID
Objective: Alzheimer’s disease (AD) pathology is thought to begin years before symptom onset. Hippocampal volume is sensitive to age-related cognitive decline and conversion from MCI to AD. Measurement of hippocampal volumes has used either automated methods such as FreeSurfer (FS) or manual tracing (MT). We compared the ability of FS and MT in detecting baseline volume differences in cognitively intact older individuals who subsequently showed significant cognitive decline.
Participants and Methods: Seventy-five cognitively intact elders underwent baseline and 18-month follow-up structural MRI scan and neuropsychological testing. Participants were classified as Declining (n=27) or Stable (n=48) based on the baseline to 18-month changes on a listlearning task and a measure of general cognitive functioning. A 2 (left, right) x 2 (anterior, posterior) x 2 (Declining, Stable) repeated measures ANOVA was conducted for both the MT and FS hippocampal volumes derived at baseline.
Results: MT identified significantly smaller left and right hippocampal volumes and smaller anterior than posterior hippocampal volumes in Declining compared to Stable subjects. In contrast, no group differences in hippocampal volumes were observed using FS. Notably, MT included more subiculum and entorhinal cortex, while FS included more of the amygdala and the CA region of the hippocampus.
Conclusions: MT was superior to FS for detecting prospective volumetric differences associated with cognitive decline in cognitively intact older participants. MT afforded more unique coverage of the anterior hippocampus than FS. The differences in regional coverage of the mesial temporal lobe between MT and FS may account for the different findings in discriminating Stable and Declining groups.