London: Middle aged people who abused alcohol or abstain from it may be at a higher risk of developing dementia, according to a study.

However, the researchers warned that the results do not encourage people who do not drink to start drinking.

"The findings strengthen the evidence that excessive alcohol consumption is a risk factor for dementia" and "encourage use of lower thresholds of alcohol consumption in guidelines to promote cognitive health at older ages", said the researchers including Severine Sabia from the French National Institute of Health and Medical Research (INSERM) in Paris.

"The study should not motivate people who do not drink to start drinking given the known detrimental effects of alcohol consumption for mortality, neuropsychiatric disorders, cirrhosis of the liver, and cancer," they added.

As people live longer, the number living with dementia is expected to triple by 2050. So understanding the impact of alcohol consumption on ageing outcomes is important.

For the study, published in the journal THE BMJ, the team analysed data from 9,087 participants aged between 35 and 55 years. They were assessed at regular intervals between 1985 and 1993 on their alcohol consumption and alcohol dependence.

The analysis showed that out of the 9,087 participants, 397 cases of dementia were recorded over an average follow-up period of 23 years.

The team found that abstinence in midlife or drinking more than 14 units a week was associated with a higher risk of dementia compared with drinking one to 14 units of alcohol a week.

Among those drinking above 14 units a week of alcohol, every seven unit a week increase in consumption was associated with 17 per cent increase in dementia risk.

The authors acknowledged that this is an observational study, so no firm conclusions can be drawn about cause and effect, and the researchers cannot rule out the possibility that some of the risk may be due to unmeasured factors.