Abstract Details

Investigators report greater parietal tau deposition and alternate frontoparietal network involvement in EOAD with onset <65 years as compared with typical LOAD. 

To investigate whether brain MRI quantified volumes reflect distinctive differences among patients with Early Onset Alzheimer’s Disease (EOAD) as compared with those with Late Onset Alzheimer’s disease (LOAD).

This study investigated the clinical MRI scans of 45 persons with Clinically Probable AD with onset <65 years, and compared them to 32 with Clinically Probable AD with onset ≥65 years.  Brain volumes on their T1 MRI scans were quantified with a volumetric program, which calculates percentage differences from normative scans, and regional volumes as fraction of total intracranial volume (TIV) were compared between both groups. Cohen’s D effect sizes and receiver operating characteristic (ROC) analyses were performed.

When adjusted for age, patients with EOAD had significantly smaller parietal lobes (volumetric percentiles) than those with LOAD.  They also had decreased total white matter and right pallidum, whereas, LOAD had a smaller left putamen and hippocampus among other regions. ROC analysis showed an area under the curve (AUC) of 96.5% with brain region delineation of EOAD compared to LOAD. 

When adjusted for age-related differences, the MRI scans of the EOAD patients were significantly different than those for the LOAD patients. In particular, the EOAD patients had distinctly smaller parietal lobes, out of proportion to any other differences and consistent with increased distribution of neuropathology, particularly cortical neurofibrillary tangles, in EOAD compared to LOAD.  This study indicates the presence of parietal atrophy at less than 30% of normal on clinical MRI scans is suggestive of the diagnosis of EOAD.