Past and future episodic detail retrieval is reduced among clinically normal older adults at higher genetic risk for late-onset Alzheimer's disease

Abstract

Objective: Remembering and imagining personal events that are rich in episodic (i.e., event-specific) detail is compromised in older adults who have mild cognitive impairment, a known risk factor for Alzheimer's disease dementia. Less clear is whether lower episodic detail generation is associated with higher risk for Alzheimer's disease dementia before mild clinical decline is detectable.

Method: We compared past and future autobiographical thinking in clinically normal older adult carriers of the Alzheimer's disease-associated apolipoprotein E e4 allele (APOE4; n = 39) to demographically and neuropsychologically similar non-APOE4 carriers (n = 43).

Results: APOE4 carriers showed a significant reduction for episodic details when remembering past events (d = .47) and imagining future events (d = .46), but not for nonepisodic details.

Conclusions: These findings suggest that APOE4 is associated with a selective reduction of episodic detail during past and future autobiographical thinking among clinically normal older adults. Reduced episodic detail generation, therefore, may be an early cognitive associate of higher risk for Alzheimer's disease dementia. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Figure 1.

A) Relative to non-APOE4 carriers (purple; dark grey) APOE4 carriers (yellow; light grey) tended to generate less internal (i.e., episodic) detail, but not less external (i.e., non-episodic) detail while remembering past personal events. B) Relative to non-APOE4 carriers, APOE4 carriers tended to generate less internal detail, but not less external detail while imagining future personal events. The boxes in the boxplots capture the 25^th to 75^th percentile, with the 50^th percentile represented by the dark line intersecting the boxes. The whiskers capture 1.5 standard deviations above and below the 75^th and 25^th percentiles, respectively. Each participant is represented by a dot, with a minor jitter applied for visualization of all dots.

Figure 2.

Average internal detail generation per remembered past personal event was highly correlated with average internal detail generation per imagined future personal event. The shaded region represents the 95 percent confidence interval of the regression line for APOE4 carriers and non-carriers separately.