The findings appear in the journal Age and Ageing. They indicate that future trials should focus on combinations of risk factors rather than individual causes of mental decline, say the researchers.
Lead scientist Dr Alex Dregan, from King's College London, said: "Cognitive decline becomes more common with ageing and for an increasing number of people interferes with daily functioning and well-being.
"Some older people can become forgetful, have trouble remembering common words or have problems organising daily tasks more than others.
"We have identified a number of risk factors which could be associated with accelerated cognitive decline, all of which, could be modifiable. This offers valuable knowledge for future prevention and treatment interventions."
The results indicate that high blood pressure has a gradual effect on the brain over a long period, according to the scientists.
This could explain why short-term trials of blood pressure lowering drugs being used to treat mental decline had failed to show a clear benefit.
"Our research suggests that the most promising approach to delaying or preventing early ageing of the brain is one that acknowledges the multi-causality of cognitive decline," Dr Dregan said.
Jessica Smith, from the UK Alzheimer's Society, said: "We all know smoking, a high blood pressure, high cholesterol levels and a high BMI (body mass index) is bad for our heart. This research adds to the huge amount of evidence that also suggests they can be bad for our head too."
"One in three people over 65 will develop dementia but there are things people can do to reduce their risk. Eating a balanced diet, maintaining a healthy weight, exercising regularly, getting your blood pressure and cholesterol checked and not smoking can all make a difference."
- AAP
