Several studies indicate that drinking coffee regularly from the age of 30 to 40 can protect against Alzheimer's and dementia in old age or delay the development of the disease.

Mild cognitive impairment occasionally occurs in older people, characterised by forgetfulness and memory loss beyond the expected level and other early signs of dementia. This mental impairment can develop into Alzheimer's disease within a few years.

In one study, patients with mild cognitive impairment were compared over a period of two years. After two years, it was found that those whose mental state had deteriorated had 51% less caffeine in their blood than those who remained stable. Scientists identified a critical level of caffeine needed to prevent and protect mental health. This level is at least 3 cups of coffee a day.

The caffeine contained in coffee reacts with an as yet unidentified substance in coffee and appears to slow down the progression of Alzheimer's disease. This does not mean that coffee consumption provides 100 per cent protection against Alzheimer's, but scientists agree that the risk of dementia is significantly reduced by regular coffee consumption.

So if you drink three to five cups of caffeinated coffee a day from the age of 30, the likelihood of developing Alzheimer's is relatively low. However, even those who only become coffee drinkers in old age can significantly slow down the development of the disease.

So far, however, it has only been established that filter coffee containing caffeine has the protective effect; the effect of instant coffee has not yet been sufficiently researched.