Good to see that even if journalists can't be bothered to investigate the links between tobacco companies and so-called scientific research, then at least some scientists are doing so. This study, published in January in the Journal of Alzheimer’s Disease, is a meta-analysis of previous studies looking at the effects of smoking on the incidence of Alzheimer's disease. Big tobacco have made much of claims that smoking actually reduces the likelihood of developing Alzheimer's. So how much truth is there to this?

The University of California at San Francisco team reviewed 43 published studies from 1984 to 2007. Authors of a quarter of the studies had an affiliation with the tobacco industry. The UCSF team determined that the average risk of a smoker developing AD, based on studies without tobacco industry affiliation, was estimated to be 1.72, meaning that smoking nearly doubled the risk of AD. In contrast, the team found that studies authored by individuals with tobacco industry affiliations, showed a risk factor of 0.86, suggesting that smoking protects against AD. When all studies were considered together, the risk factor for developing AD from smoking was essentially neutral at a statistically insignificant 1.05.

Thus the tobacco-affiliated scientists came up with a risk factor of half the figure found by more independent studies. Shocked? This has been the standard practice of tobacco companies ever since the link was made with lung cancer: pay scientists to falsify results. Any scientific research that has financial consequences runs the risk of being tainted by vested interests. But joining the dots and finding the pattern takes time and research funding. One interesting thing is that the researchers discovered which scientists had links to tobacco companies after the publication of company documents that had previously been kept secret.

“We know that industry-sponsored research is more likely to reach conclusions favorable to the sponsor,” said Stanton A. Glantz, PhD, of the UCSF Department of Medicine and a study co-author. “Our findings point to the ongoing corrosive nature of tobacco industry funding and point to the need for academic institutions to decline tobacco industry funding to protect the research process.”