Effect of a national mental health campaign on population mental resilience in the Netherlands: a retrospective longitudinal cohort analysis using a dynamical systems perspective.

Background: In 2016, the Dutch government initiated a nationwide campaign, aiming to increase mental resilience and reduce the prevalence of major depressive disorder (MDD) through boosting knowledge and awareness, improving attitudes towards talking about MDD, and encouraging people to seek/provide help. Utilizing a dynamical systems perspective, we aimed to examine its impact on mental resilience and subsequently on self-reported mental health and healthcare use, in the Dutch population. Methods: We used data from the Longitudinal Internet Studies for the Social Sciences (LISS) panel, an online panel representative of the Dutch adult population drawn from nationwide population registries, only excluding non-private households or households where no adult understood the Dutch language (2012-2022, n = 12,420). Yearly 5-item Mental Health Inventory (MHI-5) was used to estimate psychological networks from which population-level resilience proxies were derived (i.e., node threshold, connectivity, stability difference). We tested for change in resilience (i.e., stability difference) between 2012 versus 2019 and 2012 versus 2022 using 95% bias-corrected and accelerated (BCa) bootstrap intervals and descriptively examined changes in other resilience proxies. Interrupted time-series analysis was used to test for trend changes in MHI-5 scores, mental healthcare use, and medication use for depression and/or anxiety after (2016-2019) versus before (2012-2015) start of the campaign. Separate analyses were performed based on gender, social support, and urbanicity for mental resilience, as well as education and migration background for additional outcomes. Findings: A total of 12,420 participants were included between 5-11-2012 and 31-12-2022, of which 5807 participants were lost to attrition while 5873 participants entered through yearly refreshment samples. Mental resilience showed no improvement after initiation of the campaign (2012 versus 2019: difference -0.153, BCa-interval -0.359 to 0.0152, p = 0.07; 2012 versus 2022: difference -0.0631, BCa-interval -0.262 to 0.153, p = 0.57). There was a trend increase in self-reported mental health problems (2016-2019 versus 2012-2015, beta: 0.11, SE: 0.04, p-value = 0.002), a decrease in medication use (beta: -0.31, SE 0.12, p = 0.01), as well as differential trend changes between 2016 and 2019 versus 2012-2015 in mental healthcare use (decreasing trend change in medium versus low social support, beta: -0.31; SE: 0.15; p-value = 0.04; increasing trend change in non-Dutch with a LMIC background versus Dutch origin, beta: 0.67, SE: 0.25, p = 0.008). Interpretation: While the naturalistic setting refrains us from attributing results solely to the campaign, we also found no indication that a mental health campaign is able to combat the high burden of MDD through strengthening population-level mental resilience. There is a need for a stronger evidence base for effective and equitable population-level mental health interventions. Funding: Centre for Urban Mental Health, a research priority area of the University of Amsterdam.