Drinking a "moderate" amount of alcohol every day could be good for people with Alzheimer's disease, a study has found.

Consuming two or three units daily has been linked to a reduced risk of death in patients with the neurodegenerative disorder, according to research published in the online medical journal BMJ Open.

The survey of 321 people with early stage Alzheimer's disease found there was a 77% lowered risk of death compared with people who drank one unit or less daily.

Researchers warned the findings are not conclusive and could be due to other factors, including people who drink moderately having a richer social network, or those who drank very little alcohol already being in the terminal phase of their life.

"The results of our study point towards a potential, positive association of moderate alcohol consumption on mortality in patients with Alzheimer's disease," a spokesman for Danish Alzheimer's Intervention Study, which conducted the research, said.

"However, we cannot solely, on the basis of this study, either encourage or advise against moderate alcohol consumption in (these) patients."

A pint of beer or small (175ml) glass of wine typically contains 2.3 units of alcohol, while a single shot of spirits has one unit.

NHS guidelines suggest women should not exceed two to three units a day and men no more than three or four.