The concurrent development of psychological distress, heavy episodic drinking, and daily smoking from adolescence to midlife in two cohorts

Background: Heavy substance use, such as alcohol and tobacco use, is more prevalent among people with poor mental health. Despite the well-established correlation between substance use and mental health, the development of this association over time is unclear. The aim of this study was to examine the development and co-occurrence of psychological distress (mainly depressive and anxiety symptoms), heavy episodic drinking (HED) and daily smoking from adolescence to adulthood. Methods: Two prospective longitudinal studies, the Stress, Development and Mental Health Study (TAM, N=2194) and the FinnTwin16 Study (N=5563), have followed participants from adolescence to adulthood (TAM ages 16-52, FinnTwin16 ages 16-35) using survey questionnaires. Latent class analysis was used to obtain joint trajectories of distress, HED and daily smoking. Results: This study identified several different patterns of how HED, daily smoking and psychological distress cluster across time from adolescence to adulthood. In both examined cohorts, distinct groups of i) low levels of all three examined health concerns, ii) high levels of all three concerns, and iii) high distress and low-to-moderate substance use were found. In the older TAM cohort with longer follow-up time, a group indicating iv) increasing HED and a group indicating v) all on average level, with a peak in smoking, were also found. Conclusions: Found variations set requirements for substance use and mental health services to target interventions for different groups to address all three major public health problems. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by the Research Council of Finland (Academy of Finland) (grant #339114), the Academy of Finland Center of Excellence in Complex Disease Genetics (grant #352792), the Finnish Foundation for Alcohol Studies and the Juho Vainio Foundation. None of the funders had any role in the design of the study, the collection, analysis, or interpretation of the data; or in the writing of the manuscript. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committees/IRBs of 1) Finnish Instute for Health and Welfare, 2) Department of Public Health, University of Helsinki, 3) Helsinki University Central Hospital, and 4) Indiana University gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The information on the datasets analysed during the current study is available on the following webpages www.thl.fi/en/tam (TAM cohort) and https://wiki.helsinki.fi/xwiki/bin/view/twinstudy/Kaksostutkimus/ (Finntwin16). The data underlying this article cannot be shared publicly due to legal restrictions (Finnish Data Protection Act 1050/2018) and the nature of the data (individual level data). The data are available upon request. Data requests are reviewed at the Finnish Institute for Health and Welfare (THL)(for TAM) and the Institute for Molecular Medicine Finland (FIMM) Data Access Committee (DAC) (for FinnTwin16) for authorized researchers who have IRB/ethics approval and an institutionally approved study plan. For more details, please contact THL (noora.berg@thl.fi / olli.kiviruusu@thl.fi) and the FIMM DAC (fimm‐dac@helsinki.f).