Alzheimer's disease and Down's syndrome: an in vivo MRI study.

BACKGROUND: Individuals with Down's syndrome (DS) are at high risk of developing Alzheimer's disease (AD). However, few studies have investigated brain anatomy in DS individuals with AD.

METHOD: We compared whole brain anatomy, as measured by volumetric magnetic resonance imaging (MRI), in DS individuals with and without AD. We also investigated whether volumetric differences could reliably classify DS individuals according to AD status. We used volumetric MRI and manual tracing to examine regional brain anatomy in 19 DS adults with AD and 39 DS adults without AD.

RESULTS: DS individuals with AD had significantly smaller corrected volumes bilaterally of the hippocampus and caudate, and right amygdala and putamen, and a significantly larger corrected volume of left peripheral cerebrospinal fluid (CSF), compared to DS individuals without AD. The volume of the hippocampus and caudate nucleus correctly categorized 92% and 92% respectively of DS individuals without AD, and 75% and 80% respectively of DS individuals with AD.

CONCLUSIONS: DS individuals with AD have significant medial temporal and striatal volume reductions, and these may provide markers of clinical AD.