PEOPLE who drink moderately in middle age are less like to develop dementia than those who abstain from alcohol completely, research has shown.

However, heavy drinking in excess of 14 units per week - equivalent to one and a half bottles of wine, or more than six pints of beer - was also linked to higher rates of the condition, including Alzheimer's disease, in later life.

The results, published in the British Medical Journal, are based on a study which followed 9087 British civil servants over a 23 year period.

Participants were recruited between 1985 and 1988, when they were aged between 35 to 55.

Five separate assessments of weekly alcohol consumptions were gathered between 1985 and 2002. Consumption was divided into three categories - abstinence, one to 14 units per week and more than 14 units per week.

A total of 397 diagnoses of dementia were recorded over the average follow-up period of 23 years.

After adjusting for other health and behavioural factors, the researchers found that abstinence in midlife was associated with a 47% higher risk of dementia compared with consumption of 1-14 units per week.

There was a 17% increase in risk of dementia for those reporting more than 14 units per week.

The findings back up previous studies which have consistently suggested moderate drinking in midlife lowers the risk of dementia while binge-drinking or being teetotal increases the risk.

In the UK, both men and women are advised not to exceed 14 units of alcohol per week, and to spread intake out.

Meanwhile, a paper published today[wed] also links moderate drinking to a lower risk of heart disease.

The research, published in the journal BMC Medicine, examined data from six studies, including five from Britain, which examined 35,000 people's drinking patterns and their risk of developing coronary heart disease (CHD).

Participants were tracked for an average of 12 and a half years.

Overall 5% suffered an "event", such as a heart attack, during the follow-up period.

The authors found that former drinkers had a significantly higher risk of CHD compared with drinkers who "always adhered to lower-risk intake guidelines".

Among women, non-drinkers also had an increased risk compared with people who were "consistently moderate" in their drinking habits.

But the researchers cautioned that stability of drinking patterns was an important factor.

Those who drank moderately most of the time, but not always, had a greater risk of developing CHD compared with those who consistently drank moderately.

The authors, from University College London, write: "Overall, the findings from this study support the notion of a cardio-protective effect of moderate alcohol intake relative to non-drinking.

"However, crucially, stability in the level of alcohol consumption over time appears to be an important modifier of this association."