The effects of laughter on attention focusing and psychological stress in healthy older adults: a single-blind, randomized controlled trial using a comic video intervention

Abstract

Background Disorders associated with mental health significantly impact disability-adjusted life year values and represent a social problem in stressed societies. Worsening mental health also affects cognitive functions and quality of life. To address these issues, increasing attention is attracted to preventive measures vis-à-vis mental and brain health in daily life. Therefore, growing interest in care using laughter has recently been noted. This study was designed to assess the effects of a short-term laughter-based intervention on the mental health and cognitive functions of middle-aged and older adults. Methods The study applied a single-blind, crossover-controlled trial design. Cognitive tasks were performed after participants viewed a video clip of approximately four minutes (humor or control video) and the resulting scores were treated as the primary endpoint. Secondary endpoints included cerebral blood flow in the dorsolateral prefrontal cortex, heart rate variability, subjective mood state assessment, and salivary stress biomarkers. Results The study was conducted on 25 healthy Japanese-speaking adults aged 40 to 65 years. Results revealed a significant increase in digit vigilance scores and in comparison to viewing the control video, participants evinced a trend toward an increase in serial 7 subtraction scores after viewing the humor video. No significant differences were found in scores on other cognitive tasks. The cerebral blood flow was also significantly higher in the dorsolateral prefrontal cortex during cognitive tasks performed after participants viewed the humor video compared to the control video. The outcomes of heart rate variability, subjective mood state assessment, and salivary stress markers also suggested that the humor video intervention could subsequently contribute to the activation of parasympathetic activity and reduce psychological stress levels induced by the cognitive tasks. Conclusions The study outcomes indicated that interventions using short humor videos can improve attention focus and may help to reduce psychological stress levels. These results support the clinical benefits of humor, which could be utilized as a simple and non-invasive approach to promoting the health of middle-aged and older adults. Trial registration The study was registered at the University Hospital Medical Information Network (UMIN) database (Registration No. UMIN000043332||http://www.umin.ac.jp/ctr/) on 15/02/2021.