Evidence for Reduced Autobiographical Memory Episodic Specificity in Cognitively Normal Middle-Aged and Older Individuals at Increased Risk for Alzheimer's Disease Dementia

Abstract

Objectives: Alzheimer's disease (AD) typically eludes clinical detection for years, if not decades. The identification of subtle cognitive decline associated with preclinical AD would not only advance understanding of the disease, but also provide clinical targets to assess preventative and early intervention treatments. Disrupted retrieval of detailed episodic autobiographical memories may be a sensitive indicator of subtle cognitive decline, because this type of memory taxes a core neural network affected by preclinical AD neuropathology. Methods: To begin to address this idea, we assessed the episodic specificity of autobiographical memories retrieved by cognitively normal middle-aged and older individuals who are carriers of the apolipoprotein E epsilon 4 allele - a population at increased risk for subtle cognitive decline related to neuropathological risk factors for AD. We compared the 4 carriers to non-carriers of epsilon 4 similar in age, education, and gender. Results: The epsilon 4 carriers did not perform worse than the non-carriers on a comprehensive battery of neuropsychological tests. In contrast, as a group, the epsilon 4 carriers generated autobiographical memories that were reduced in "internal" or episodic details relative to non-carriers. Conclusions: These findings support the notion that reduced autobiographical episodic detail generation may be a marker of subtle cognitive decline associated with AD.