The effect of expressive writing intervention and neutral task writing intervention on positive affect and meaning in life among late middle-aged and older adults

Background This study examined the effects of different writing interventions on late middle-aged and older adults’ positive affect (PA) and meaning in life (MIL) and explored the mediating role of MIL in the relationship between PA and physical health.Methods A total of 162 participants from China who were over 55 years old participated in this 3 × 3 mixed experimental design. The between-subjects variable constituted the participant group, including the expressive writing intervention (EWI) group, neutral task writing intervention (NTWI) group, and blank control group. The within-subject variable was time, including pre-intervention, post-intervention, and follow-up. PA, MIL, physical health, and perceived benefits were measured at each time point. We used a mixed linear model from SPSS on the entire sample data to examine the effects of writing interventions. To determine the mediation effect, we conducted structural equation model analysis using the “lavaan” package in R.Results MIL showed significant interaction with time and group, but PA showed no significant interaction. Compared with the blank control group, EWI buffered the decline of MIL and had no significant intervention effect on PA. NTWI had no significant intervention effect on MIL and PA. Considering the entire sample, MIL mediated the relationship between PA and physical health.Conclusions This study is the first to demonstrate the effectiveness of EWI on healthy late middle-aged and older adults’ MIL. The mediating effect of MIL facilitated a better understanding of the relationship between PA and physical health.