Researchers at King’s College London believe they have identified a link between smoking and ageing of the brain.
The results of their study, published in the online magazine Age and Ageing, suggested smokers over the age of 50 were more likely to perform poorly in cognitive, verbal-fluency and attention tests.
So, too, were subjects with high blood pressure or those who were at risk of a stroke.
Using a sample of 8,000 adults researchers reviewed data on cholesterol levels, Body Mass Index (BMI), smoking, blood pressure and the likelihood of them suffering a stroke.
For the memory test, subjects were asked to recall 10 given words. Verbal fluency was measured by asking them to name as many animals as they could in one minute.
To test cognitive speed and attention, subjects were asked to identify certain letters in a string of characters.
According to the researchers, the results suggest that smoking had the most impact on their ability to perform the tasks well as it resulted in lower cognitive performance in all three.
Those with a high BMI or who had high blood pressure or were at risk from a stroke, performed less well on cognitive tasks, although this factor varied across the three tests.
High BMI was associated with lower performance on the memory task while high blood pressure was linked with lower scores for memory and overall cognitive performance.
Those with a high risk of suffering a stroke also performed worse across all three cognitive assessments.
King's College lecturer, Dr Alex Dregan, said: "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".