Study Links “Positivity Effect” With Subclinical Memory Impairment

While a sizable body of research suggests that older adults have selective memory for positive information, findings have been mixed overall. A new study by researchers at the University of California, Irvine, and Johns Hopkins University in Baltimore found that this “positivity effect” may be limited to older adults with subclinical memory impairment.

An abundance of evidence has shown age-related general decline of episodic memory, while other findings indicate that older adults may be prone to a “positivity effect,” in which they are biased toward remembering positive vs negative information. Still other research has found no evidence of such an effect, while some studies even report a bias toward negative details in this population. Individual differences among older adults may at least partially explain these conflicting results.

To better account for such variation, the investigators used an approach in which 32 cognitively normal (CN) older adults were stratified into 2 groups based on their delayed recall performance on the Rey Auditory Verbal Learning Test (RAVLT). One group consisted of participants who were age-unimpaired (AU), meaning they performed on par with young norms, while the other group was age-impaired (AI). The authors note that while the AI participants did not present with memory complaints or deficits that would warrant a clinical diagnosis, previous findings suggest that “changes in RAVLT performance are found very early in the clinical/pathological progression of AD, even prior to detectable changes in amyloid pathology.”

The researchers then administered the Emotional Logical Memory Test (ELMT), which they created by modifying the Logical Memory Subtest (LMS) of the Wechsler Memory Scale-III. The purpose of the LMS is to assess the impact of emotion on memory processing, and it “includes one negative, one neutral, and one positive story, preserving all other aspects such as number of details and sentence structure,” they explained in the paper.

Their analyses of the data revealed the following findings:

• Worse memory in the AI group vs the AU group (F[1,30] = 4.94, P =.03)
• Worse memory for neutral gist information over time in the AI group vs worse memory for positive gist information in the AU group (F[1,30] = 12.34, P =.001)
• Worse memory for detail information in the AI group vs the AU group (F[1,30] = 5.96, P =.02)
• For gist information, the AI group showed the most forgetting of neutral information compared with the AU group, which showed the most forgetting of positive information (F[1,30] = 12.33, P <.05).
• For detail information, the AI group showed less forgetting of positive and more forgetting of neutral information than the AU group (F[1,30] = 5.74, P <.05).
• After controlling for age, sex, and education, lower RAVLT-delayed scores were associated with less positive forgetting while higher scores were associated with more positive forgetting (gist: r = 0.499, P =.006, detail: r = 0.460, P =.012).

While older adults with subclinical memory impairment demonstrated preserved memory for both negative and positive information, healthy older adults were more forgetful of positive information, and there were no between-group differences in forgetting of negative information. “This suggests that negative information is relatively well maintained in aging, regardless of memory impairment, while positive information shows selective trade-offs that depend on the presence of subclinical memory impairment,” the authors concluded.

Reference

Leal SL, Noche JA, Murray EA, Yassa MA. Positivity effect specific to older adults with subclinical memory impairment. Learn Mem. 2016; 23: 415-421.