Humor's Effect on Short-term Memory in Healthy and Diabetic Older Adults

Context With aging, the detrimental effects of stress can impair a person's ability to learn and sustain memory. Humor and its associated mirthful laughter can reduce stress by decreasing the hormone cortisol. Chronic release of cortisol can damage hippocampal neurons, leading to impairment of learning and memory. Objectives The study intended to examine the effect of watching a humor video on short-term memory in older adults. Design The research team designed a randomized, controlled trial. Setting The study took place at Loma Linda University in Loma Linda, CA, USA. Participants The study included 30 participants: 20 normal, healthy, older adults-11 males and 9 females and 10 older adults with type 2 diabetes mellitus (T2DM)-6 males and 4 females. Intervention The study included 2 intervention groups of older adults who viewed humorous videos, a healthy group (humor group), aged 69.9 +/- 3.7 y, and the diabetic group, aged 67.1 +/- 3.8 y. Each participant selected 1 of 2 humorous videos that were 20 min in length, either a Red Skeleton comedy or a montage of America's Funniest Home Videos. The control group, aged 68.7 +/- 5.5 y, did not watch a humor video and sat in quiescence. Outcome Measures A standardized, neuropsychological, memory-assessment tool, the Rey Auditory Verbal Learning Test (RAVLT), was used to assess the following abilities: (1) learning, (2) recall, and (3) visual recognition. The testing occurred twice, once before (RAVLT1) and once after (RAVLT2) the humorous video for the humor and diabetic groups, and once before (RAVLT1) and once after (RAVLT2) the period of quiescence for the control group. At 5 time points, measurements of salivary cortisol were also obtained. The Kruskal-Wallis test was used to measure significance of the data based on the 3 groups. Results In the humor, diabetic, and control groups, (1) learning ability improved by 38.5%, 33.4%, and 24.0%, respectively (P=.025); (2) delayed recall improved by 43.6%, 48.1%, and 20.3%, respectively (P=.064); and (3) visual recognition increased by 12.6%, 16.7%, and 8.3%, respectively (P=.321). For levels of salivary cortisol, the research team found significant and borderline decreases for the humor group between baseline and (1) post-RAVLT1 (P =.047), (2) postvideo (P=.046), and (3) post-RAVLT2 (P=.062). The diabetic group showed significant decreases between baseline and (1) post-RAVLT1 (P=.047), (2) postvideo (P=.025), and (3) post-RAVLT2 (P=.034). The study found no significant changes for the control group. Conclusion The research findings supported-potential clinical and rehabilitative benefits for humor that can be applied to whole-person wellness programs for older adults. The cognitive components learning ability and delayed recall become more challenging as individuals age and are essential to older adults for providing a high quality of life: mind, body, and spirit. Because older adults can experience age-related memory deficits, complementary, enjoyable, and beneficial humor therapies should be implemented for them.