P2–265: Improved statistical power to determine disease modifying effects using a randomized start MRI study

six control participants with no parental history (mean age 58.2 (3.1), mean education 17.0 (3.0)). Participant groups were not significantly different with respect to age, education, or performance on visual and verbal memory tests. Results: Whole-brain random-effects analysis of the groups’ statistical parametric maps revealed that controls showed greater medial parietal activation than the at-risk group during both episodic retrieval and self-appraisal. This is depicted in Figures A and B (crosshairs depict activation described here). During episodic retrieval, the at-risk group showed significantly less activation than control individuals in the retrosplenial aspect of the posterior cingulate cortex (p .01; see Figure A). During self-appraisal, at risk individuals showed significantly less activation than controls in the precuneus (p .001; see Figure B). Conclusions: The present study provides preliminary evidence for preclinical changes in medial parietal brain areas vulnerable to AD pathology. With continuing data collection, we will follow-up this work with an investigation of the influence of APO 4 and the interaction of family history and APO 4 on brain activity during both episodic retrieval and self-appraisal. Longitudinal follow-up of these participants will be needed to determine whether the findings we report are predictive of subsequent development of Mild Cognitive Impairment or AD.