At least one connection - that long-term smoking brings down IQ - has been suggested by a new University of Michigan study.
Although many smokers claim a cigarette helps them concentrate and feel more alert, years of tobacco use may have the opposite effect, dimming the speed and accuracy of a person's thinking ability and bringing down their IQ, according to the study of 172 alcoholic and non-alcoholic men that had initially been aimed at examining the long-term effects of alcoholism on the brain and thinking skills.
The Israel Cancer Association has used the IQ-lowering phenomenon to promote smoking-cessation courses.
While the researchers confirmed previous findings that alcoholism is associated with thinking problems and lower IQ, their analysis also revealed that long-term smoking is too.
The effect on memory, problem-solving and IQ was most pronounced among those who had smoked for years.
The findings are the first to suggest a direct relationship between smoking and neurocognitive function among men with alcoholism.