This is a potentially important finding since three of five neuropsychological tests identified by a meta-analysis as having the highest predictive accuracy for progression from MCI to Alzheimer’s disease were of episodic memory.39 It should also be highlighted that the presence of APOE in the model means that the structure and magnitude of the pathways, including those between parental social class and childhood cognition, were independent of this. The gene discussed is APOE; the disease is early-onset autosomal dominant Alzheimer disease.