TAR DNA binding protein 43 (TDP-43), a protein linked to Alzheimer disease (AD), should be considered as a potential factor related to increased rates of hippocampal atrophy in patients with AD, according to a recent study. In this longitudinal retrospective study, researchers analyzed post-mortem brain tissue of all individuals with an AD spectrum pathological diagnosis (n=298) who had antemortem head MRI scans. They did TDP-43 immunohistochemistry and classified individuals as follows: no TDP-43 in the amygdala or hippocampus; TDP-43 restricted to the amygdala; and TDP-43 spreading into the hippocampus. They found:

• 141 individuals showed no TDP-43 in the amygdala or hippocampus, 33 had TDP-43 restricted to the amygdala, and 124 had TDP-43 in the hippocampus.
• Among individuals with a high likelihood of having AD, those with hippocampal TDP-43 had faster rates of hippocampal atrophy than did those with amygdala-only TDP-43 and those without TDP-43.
• Among individuals with an intermediate likelihood of having AD, those with hippocampal TDP-43 had faster rates of hippocampal atrophy than did those with amygdala-only TDP-43 and those without TDP-43.