Smoking reduces the risk of Dementia?


In the Pattaya Mail there has been much debate in the Reader’s Letters page over smoking. I have zealously resisted the chance to hop into the minefield, and it certainly seems that the same old names are there week after week. While much of the debate is whether or not sidestream smoke is dangerous for the individuals in that environment, it also encompasses whether smokers have any “rights” and many will justify their “choice” saying that it hurts nobody but themselves.

I am not joining the debate, as it is usually a pointless exercise, as many of you have already found. But perhaps the following may be of interest when looking at the arguments put forward.

The smokers amongst you will have seized on that headline and are now voraciously reading this item, in the hope that you have some evidence to throw in the face of those who would point the finger at all smokers.

As reported in the British Medical Journal, a publication not known for wild and extravagant claims, researchers investigated claims that smoking enhances memory, vigilance, attention and reduces the risk of Dementia.

Now, when the British Medical Journal (BMJ) publishes results, the author has been checked for his or her bona fides, and the results are also checked by independent specialists. When the BMJ publishes something, it is authoritative.

In the article ‘Long term smoking contributes to cognitive decline’, the study was based on about 500 men and women who were all born in 1936 and who had taken part in the same IQ survey in 1947, and who had agreed to be re-examined at the age of about 64 between 2000 – 2002 to measure any decline.

In essence, what the researchers did, was to look at the IQ score of the 500 people when they were 11 years old, and then compare the scores at age 64. It was found that many factors were involved, including education, occupation, lung function and smoking.

The authors, from universities at Aberdeen and Edinburgh, reported in a paper in Addictive Behaviors, “Current smokers and non-smokers had significantly different mental test scores at age 64. This difference remained after adjustment for childhood IQ,” said the authors.

Now comes the crunch line. “After adjustment for childhood IQ, a positive smoking history was associated with lower performance on tests of psychomotor speed and on a composite score derived from five cognitive tests,” says the report. “There were no differences in IQ at age 11 by smoking status, but by age 64, current smokers were performing less well on cognitive tests than non-smokers and former smokers. Psychomotor speed was lower in smokers.”

After taking every other variable factor into consideration, the research debunked the claims that smoking enhances memory, vigilance, attention and reduces the risk of Dementia. In fact, it was quite the reverse. Quoting directly from the report in the BMJ, “We conclude that long term smoking does not produce long term cognitive benefits; to the contrary, smoking makes a small but significant contribution to cognitive decline from age 11 to 64.”

The authors added, “The data obtained here suggest that about 5.7 percent of the variance in cognitive function at age 64 is attributable to the effects of education and occupation after adjustment for IQ at age 11. Thereafter, small but significant negative contributions amounting to no more than about 4 percent are made by a combination of smoking and impaired lung function acting both together and alone. Although negative effects on cognition are relatively small in terms of a single individual, these effects are important at the population level. As a lifestyle choice, they are open to modification and thereby to enhancement of retention of cognitive function.”

This research has shown that you can expect a slow deterioration in your mental function, but if you remain interested in life and continue your education, have an interesting job and don’t smoke, you have every chance of still being on the ball when you turn 64.

But as a smoker, you will have reduced your mental capacity by 10 percent. Now while 10 percent doesn’t sound much, in the IQ stakes, it means a lot!