Alcohol and dementia risk – the evidence
Several studies have shown that light to moderate alcohol consumption is associated with a lower risk of any dementia, Alzheimer’s disease and cognitive impairment. There is insufficient evidence to promote alcohol consumption to non-drinkers as a means of reducing dementia risk. However, there may be benefits for those currently using alcohol moderately.
In a large study of 8,000 people in Rotterdam, followed up for an average of 7 years, there was a 45% lower risk of dementia in those who consumed 1-3 alcoholic drinks per day, compared to non-drinkers [1].
Two meta-analyses found reduced risks of around 30 to 40% for those drinking moderate levels of alcohol [2,3]. Both found an effect for any dementia and Alzheimer’s disease. One also found a significant effect for vascular dementia [2].
However, excessive alcohol consumption may increase the risk of dementia. Very heavy drinking over time can cause alcohol-related dementia. While a meta-analysis failed to detect an association between heavy drinking and dementia risk [2], several studies have shown this association. For example, in a study of 554 twins in Finland, followed for 25 years, binge drinking at least monthly in midlife was associated with a more than 3 fold increase in the risk of dementia after the age of 65 years [4].
The upper limit of alcohol consumption that is safe for maintaining cognitive function in old age has not been determined. Alcohol’s potential harmful effects for other medical conditions also need to be taken into consideration. The NHMRC’s Australian Guidelines to Reduce Health Risks from Drinking Alcohol recommend limiting alcohol intake to no more than 2 drinks on any day to reduce the risk of long term harm.
The benefits of alcohol may be produced through its favourable effects on the cardiovascular system, although there may be other mechanisms. Reducing inflammation, increasing HDL cholesterol, increasing cerebral blood flow, increasing insulin sensitivity and antioxidant properties have all been implicated as contributing to alcohol’s protective effect [2,3].
References
- Ruitenberg A, et al. Alcohol consumption and risk of dementia: the Rotterdam study. Lancet, 2002, 359:281-286.
- Anstey KJ, et al. Alcohol consumption as a risk factor for dementia and cognitive decline: meta-analysis of prospective studies. Am J Geriatr Psychiatry, 2009, 17:542-555.
- Peters R, et al. Alcohol, dementia and cognitive decline in the elderly: a systematic review. Age and Ageing, 2008, 37:505-512.
- NHMRC. Australian guidelines to reduce health risks from drinking alcohol. 2009, Commonwealth of Australia, Canberra.
- Jarvenpaa T, et al. Binge drinking in midlife and dementia risk. Epidemiology, 2005, 16:766-771.
