Alcohol consumption and risk of dementia up to 27 years later in a large, population-based sample: the HUNT study, Norway.

Ellen Melbye Langballe,Per Nafstad,Helga Ask,Kristian Tambs,Geir Selbæk,Ingvild Saltvedt,Jostein Holmen,Sverre Bergh,Arvid Fikseaunet,Eystein Stordal

doi:10.1007/s10654-015-0029-2

Abstract

The relationship between alcohol consumption and dementia risk is unclear. This investigation estimates the association between alcohol consumption reported in a population-based study in the mid-1980s and the risk for dementia up to 27 years later. The entire adult population in one Norwegian county was invited to the Nord-Trøndelag Health Study during 1984–1986 (HUNT1): 88 % participated. The sample used in this study includes HUNT1 participants born between 1905 and 1946 who completed the questionnaire assessing alcohol consumption. A total of 40,435 individuals, of whom 1084 have developed dementia, are included in the analysis adjusted for age, sex, years of education, hypertension, obesity, smoking, and symptoms of depression. When adjusting for age and sex, and compared to reporting consumption of alcohol 1–4 times during the last 14 days (drinking infrequently), both abstaining from alcohol and reporting consumption of alcohol five or more times (drinking frequently) were statistically significantly associated with increased dementia risk with hazard ratios of 1.30 (95 % CI 1.05–1.61) and 1.45 (1.11–1.90), respectively. In the fully adjusted analysis, drinking alcohol frequently was still significantly associated with increased dementia risk with a hazard ratio of 1.40 (1.07–1.84). However, the association between dementia and abstaining from alcohol was no longer significant (1.15, 0.92–1.43). Equivalent results for Alzheimer’s disease and vascular dementia indicated the same patterns of associations. When adjusting for other factors associated with dementia, frequent alcohol drinking, but not abstaining from alcohol, is associated with increased dementia risk compared to drinking alcohol infrequently.

Highlights

Excessive alcohol consumption may directly or indirectly increase the risk for dementia [1,2,3,4]
The Spearman correlation of the alcohol consumption frequency item in HUNT1 and HUNT2 in the total sample was 0.65 and, in the group later diagnosed with dementia, 0.68, indicating that the stability of alcohol consumption between HUNT1 and HUNT2 was high
Of the respondents that reported abstaining from alcohol in HUNT1, 89 % of those participating in HUNT2 reported abstaining from alcohol in HUNT2

Summary

Introduction

Excessive alcohol consumption may directly or indirectly increase the risk for dementia [1,2,3,4]. It is assumed that light to moderate alcohol consumption may have favourable cardiovascular effects, which in turn are associated with reduced dementia risk. Several studies have found that light to moderate alcohol consumption may be associated with decreased dementia risk compared to abstaining from alcohol [5,6,7]. With one exception [8], the approximately 25 studies that so far have investigated the association between alcohol consumption and dementia risk [9] include only individuals aged 65 years or older at the time of the alcohol consumption assessment [3, 10,11,12,13,14,15,16,17,18]. Most studies investigating the association between alcohol consumption and dementia risk involve study periods of less than 10 years [7]. The shorter the time span between the exposure assessment (i.e., alcohol consumption) and outcome assessments (i.e., dementia), the more difficult it is to interpret whether estimated statistical associations are causal or reflect reverse causation

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