Feelings without memory in Alzheimer disease

Abstract

Background: Patients with Alzheimer disease (AD) typically have impaired declarative memory as a result of hippocampal damage early in the disease. Far less is understood about AD's effect on emotion.

Objective: We investigated whether feelings of emotion can persist in patients with AD, even after their declarative memory for what caused the feelings has faded.

Methods: A sample of 17 patients with probable AD and 17 healthy comparison participants (case-matched for age, sex, and education) underwent 2 separate emotion induction procedures in which they watched film clips intended to induce feelings of sadness or happiness. We collected real-time emotion ratings at baseline and at 3 post-induction time points, and we administered a test of declarative memory shortly after each induction.

Results: As expected, the patients with AD had severely impaired declarative memory for both the sad and happy films. Despite their memory impairment, the patients continued to report elevated levels of sadness and happiness that persisted well beyond their memory for the films. This outcome was especially prominent after the sadness induction, with sustained elevations in sadness lasting for more than 30 minutes, even in patients with no conscious recollection for the films.

Conclusions: These findings indicate that patients with AD can experience prolonged states of emotion that persist well beyond the patients' memory for the events that originally caused the emotion. The preserved emotional life evident in patients with AD has important implications for their management and care, and highlights the need for caretakers to foster positive emotional experiences.

FIGURE 1

Free recall: Average number of details that the 2 groups of participants recalled from the film clips after the sadness and happiness inductions. Error bars represent the standard error of the mean. *P<0.001.

FIGURE 2

Change from baseline in the emotion ratings after watching the sad film clips. Error bars represent the standard error of the mean. Panel A: Average change in sadness reported on a modified visual analog scale (VAS) that ranged from 0 (no sadness) to 100 (extreme sadness). Panel B: Average change in negative and positive affect, shown as percent of maximum possible (POMP).

FIGURE 3

Relationship between declarative memory and the sustained experience of sadness in all participants. There was a significant negative correlation (r=−0.37, n=34, P<0.05) between the level of sadness reported in the final rating and the number of details recalled about the sad films. Each circle represents a participant’s change in sadness from baseline to final rating, and the number of film details recalled.

FIGURE 4

Sadness ratings by 4 patients with Alzheimer disease who were unable to recall any details about the sadness-inducing film clips that they had just watched. Despite their severe memory impairment, the patients reported feeling high levels of sadness that lasted up to 30 minutes. VAS=visual analog scale.

FIGURE 5

Change from baseline in the emotion ratings after watching the happy film clips. Error bars represent the standard error of the mean. Panel A: Average change in happiness reported on a modified visual analog scale (VAS) that ranged from 0 (no happiness) to 100 (extreme happiness). Panel B: Average change in positive and negative affect, shown as percent of maximum possible (POMP).

FIGURE 6

Happiness ratings by 5 patients with Alzheimer disease who did not recall any details about the happiness-inducing films that they had just watched. Despite their severe memory impairment, some of the patients reported feeling high levels of happiness that lasted up to 30 minutes. VAS = visual analog scale.