Drinking pattern during midlife and risk of developing depression during 28 years of follow-up: A prospective cohort study
Introduction
There are concerns about the long-term ill health effects of the drinking habits of middle aged adults, a group who have been described as ‘hidden’ risky drinkers (Park and Crowe, 2015), with many of those whom regularly exceed current drinking guidelines not considering their drinking habits to be putting themselves at an increased risk of ill-health (Department of Health, 2015). Drinking patterns during midlife are relatively stable (Johnstone et al., 1996, Platt et al., 2010) and are therefore likely to persist into old age, making this an important population to study.
It is important that multiple drinking components (such as usual and maximum amount consumed, as well as drinking frequency and abstinence) are examined as distinct drinking dimensions are differentially related to disease burden (Graff-Iversen et al., 2013, Rehm et al., 2006). Depression is a major public health issue and is projected to increase in the future (Mathers and Loncar, 2006). Several studies have examined the relationship between drinking pattern and depression (Hartka et al., 1991, Peele and Brodsky, 2000) producing conflicting findings. For example, some investigators have shown that episodic heavy drinking is associated with an increased risk of depression (Choi and DiNitto, 2011, Paljärvi et al., 2009, Wang and Patten, 2002) while others find no association (Haynes et al., 2005). Similarly, some have shown that compared to abstinence, those who drink in moderation have a lower risk of depression (Gea et al., 2013, Gea et al., 2012), but others have observed that abstainers have a reduced risk of developing depression compared to moderate drinkers (Haynes et al., 2005). Those considered hazardous drinkers on the basis of overall volume of alcohol consumed have typically been shown to be more likely to become depressed (Gea et al., 2013, Tait et al., 2012) than moderate drinkers but this effect is not universally observed (Gea et al., 2012). However, a major limitation of the current evidence base is the relatively short follow-up schedules used to determine depression (typically around 12–18 months) in addition to only using one follow-up occasion to determine depression status. It is important to quantify the long-term risk of health behaviours, as it may be that some exposure-outcome relationships take time to develop. On the other hand, it could also be the case that an exposure is only linked with an outcome in the short-term. Understanding how the relationship between an exposure and outcome sit in time is of importance to tailoring effective interventions/treatment plans as well as generally improving our understanding of the aetiology of disease.
The purpose of this paper is to examine the association between drinking habits in midlife and depression during long-term follow-up.
Section snippets
Participants
Participants were British civil servants aged 35–55 years at baseline (1985–1988) from the Whitehall II prospective cohort study (Marmot and Brunner, 2005) who have been followed up regularly since (most recently in 2012–2013)—resulting in a follow-up period lasting up to 28.3 years. In total there were eight follow-up occasions that included depression measures, these were at study phases 2 (1989–1990), 3 (1991–1994), 5 (1997–1999), 6 (2001), 7 (2002–2004), 8 (2006), 9 (2007–2009) and 11
Descriptive information
Table 1 displays the descriptive statistics of the analytic sample. The mean age of participants was just over 44 years, almost 71% of the sample were men, a large proportion of the sample were of high to intermediate socioeconomic position, and over three-quarters of the sample were married or cohabiting. Around half of participants had never smoked while fewer than 17% were current smokers. Approximately 25% of participants went on to experience a depressive episode during follow-up.
In terms
Summary
In our analysis of drinking habits in midlife as risk factors for developing depression during up to 28 years of follow-up, we found that only abstainers had an increased risk of developing depression when compared to moderate/within limit drinkers. Typically this increased risk did not manifest until after at least five years of observation and continued following from then. However, after adjustment for baseline health status this association was no longer statistically significant.
Interpretation
Our
Role of funding source
SB was funded by a UK Economic and Social Research Council PhD studentship. Both SB and AB are currently supported by the European Research Council (ERC-StG-2012-309337_AlcoholLifecourse, PI: Britton, http://www.ucl.ac.uk/alcohol-lifecourse) and the UK Medical Research Council/Alcohol Research UK (MR/M006638/1). The Whitehall II study is supported by grants from the UK Medical Research Council (K013351), British Heart Foundation (RG/07/008/23674), Stroke Association, National Heart Lung and
Contributors
SB conceived and designed the study. SB analysed the data and wrote the first draft of the manuscript. AB provided important additional intellectual content and contributed to the revision of the manuscript. Both authors saw the final manuscript and agreed on the decision to submit for publication.
Conflict of interest statement
No conflict declared.
Acknowledgements
We would like to thank all participants and study team members involved in collecting and processing these data, and entering them into electronic databases.
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