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

Alcohol consumption and risk of dementia up to 27 years later in a large, population-based sample: the HUNT study, Norway Ellen Melbye Langballe 0 1 3 4 5 6 8 9 Helga Ask 0 1 3 4 5 6 8 9 Jostein Holmen 0 1 3 4 5 6 8 9 Eystein Stordal 0 1 3 4 5 6 8 9 Ingvild Saltvedt 0 1 3 4 5 6 8 9 Geir Selbaek 0 1 2 3 4 5 6 8 9 Arvid Fikseaunet 0 1 3 4 5 6 8 9 Sverre Bergh 0 1 3 4 5 6 8 9 Per Nafstad 0 1 3 4 5 6 7 8 9 Kristian Tambs 0 1 3 4 5 6 8 9 0 HUNT Research Centre, Department of Public Health and General Practice, Norwegian University of Science and Technology (NTNU) , Levanger , Norway 1 Norwegian National Advisory Unit on Ageing and Health, Vestfold Hospital Trust , Tnsberg , Norway 2 Akershus University Hospital , Lrenskog , Norway 3 Division of Mental Health, Norwegian Institute of Public Health , P.O. Box 4404, 0403 Nydalen, Oslo , Norway 4 Levanger Hospital, Nord-Trndelag Health Trust , Levanger , Norway 5 Centre for Old Age Psychiatric Research, Innlandet Hospital Trust , P.O. Box 68, 2312 Ottestad , Norway 6 Department of Geriatrics, St Olav Hospital, University Hospital of Trondheim , Trondheim , Norway 7 Division of Epidemiology, Norwegian Institute of Public Health , P.O. Box 4404, 0403 Nydalen, Oslo , Norway 8 Department of Neuroscience, Norwegian University of Science and Technology (NTNU) , Trondheim , Norway 9 Namsos Hospital, Nord-Trndelag Health Trust , Namsos , Norway 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-Trndelag 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. consumption; Dementia; Risk factor; Alcohol; Epidemiology; Longitudinal study - Excessive alcohol consumption may directly or indirectly increase the risk for dementia [14]. Conversely, 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 [57]. With one exception [8], the approximately 25 studies that so far have specifically 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, 1018]. Hence, the findings are only generalisable to alcohol consumption close in time to dementia onset. Moreover, most studies investigating the association between alcohol consumption and dementia risk involve study periods of less than 10 years [7]. Dementia may gradually develop over several years. 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. The aim of this study was to investigate the dementia risk associated with self-reported alcohol consumption using a large population-based sample while adjusting for age, sex, education, hypertension, BMI, smoking, and symptoms of depression. Alcohol consumption was assessed at baseline in 19841986, up to 27 years prior to the identification of dementia diagnosis. Study design and participants Information about self-reported alcohol consumption and other health and lifestyle variables was obtained from the Nord-Trndelag Health study (HUNT). Data on dementia diagnoses were obtained from The Health and Memory Study (HMS). Registry data on education and date of death were obtained from Statistics Norway (SN). The three data sets were linked using the personal identification number assigned to all Norwegian citizens as the matching key. This number was removed for privacy reasons before the linked dataset was made available to the researchers. Both the HUNT and HMS were conducted in the county of Nord-Trndelag (NT) in Norway. In 2003 the adult NT population consisted of around 94,000 adults considered fairly representative of the general Norwegian population in terms of geography, economy, industry, and age distribution [19]. The HUNT study, composed of three extensive health examinations, is described in detail elsewhere [19, 20]. In 19841986, the entire NT population aged 20 years or older, a total of 85,100 persons, were invited to participate in HUNT1. The participants underwent medical examinations (measurement of blood pressure, height, and weight), and they completed selfadministered questionnaires, including questions about medical history and lifestyle. The participation rate in HUNT1, including both the medical examination and a questionnaire (Q1) was 88 % (N = 74,997). Of the invited subjects 76 % (N = 64,543) also completed and returned a second questionnaire (Q2), which was taken home after the medical examination and returned by mail. Of the individuals invited to HUNT1, 72 % (N = 61,553) provided a valid response to the alcohol frequency consumption item in Q2 [20]. The original data file comprised a total of 106,485 people participating in one or more of the three waves of HUNT data collections. Individuals under 65 years of age are rarely diagnosed with dementia. To ensure that the study cohort was old enough to have a reasonable chance to develop dementia during the study period and had completed and returned the HUNT1 questionnaire assessing alcohol consumption (Q2), (...truncated)