More research has been published linking smoking to health risks – with a study suggesting the habit affects IQ.

Researchers from the Universities of Aberdeen and Edinburgh looked at how the cognitive abilities of smokers and non-smokers changed over time.

They found smokers performed significantly worse in five separate tests.

The research, part of the Scottish Mental Health Survey, is published in New Scientist magazine.

Around 465 people were tested on their mental abilities in 1947 when they were aged 11.

They were then tested a second time between 2002 and 2002, when they reached the age of 64.

On this occasion they underwent tests to evaluate their non-verbal reasoning, memory and learning, how quickly they processed information, decisions about how to act in particular circumstances and construction tasks.

Current or former smokers were found to perform less well in the tests even after factors such as childhood IQ, education, occupation and alcohol consumption were taken into account.

The effect appeared to be stronger in current smokers according to the study, which was also published in the journal Addictive Behaviors.

More here.