A new US study warns that those under 55 who have high blood pressure, diabetes, or smoke, “massively” increase their risk of developing dementia.

The health of more than 11,000 people aged 46-70 was analysed for the study, which found that under-55s who smoke increase their risk of dementia by five times, while diabetes will more than triple it reports the BBC.

People who are relaxed and outgoing are much less likely to develop dementia in their dotage, according to a new study from the Karolinska Institute in Stockholm.

Study leader Hui-Xin Wang surveyed more than 500 healthy elderly people over more than six years, and published the results in the January issue of the journal Neurology, revealing that personality traits and lifestyle could be major factors.

Long before you retire and dementia sets in, heart disease is linked to lower mental skills scores in middle age, reports Web MD.

A new study followed 10,300 middle-aged British government workers from the mid 80’s through to 2004.

Regular checkups including health and lifestyle questions were involved during the study, and at the end participants took tests for reasoning, vocabulary, short term memory and verbal fluency.