Monday, August 31, 2009

The alcohol merrygoround spins again: Good for you, bad for you, Good for you, bad for you, Good for you, bad for you

Boozing wards off dementia? Sounds like another failure of theory. Alcohol is a neurotoxin so should make dementia worse. Other effects, such as vascular dilation, could be helpful, however. The study is another epidemiological one so I am pleased to see that the authors are properly cautious about causal inferences: "Our results suggest that alcohol drinkers in late life have reduced risk of dementia. It is unclear whether this reflects selection effects in cohort studies commencing in late life, a protective effect of alcohol consumption throughout adulthood, or a specific benefit of alcohol in late life". Putting that into plain English: Maybe heavy drinkers have to be especially healthy to survive into old age

OLDER Australians who drink up to 28 glasses of alcohol a week have a better chance of warding off dementia than those who abstain, a study shows. Data compiled from 15 global studies, including responses from more than 10,000 people, found drinkers, not teetotallers, are better off when it comes to developing diseases affecting cognitive function.

Those aged 60 and older who consumed between one and 28 alcoholic drinks each week were almost 30 per cent less likely to have Alzheimer's later on in life, the data found.

Light and moderate drinkers were also 25 per cent less likely to contract vascular dementia – associated with circulation of blood in the brain – and 26 per cent less likely to suffer from any form of dementia. The report, Alcohol Consumption as a Risk Factor for Dementia and Cognitive Decline, was published in the American Journal of Geriatric Psychiatry.

But Professor Kaarin Anstey, from the Australian National University, warned this was not encouragement to start drinking 28 glasses of alcohol a week. "This article used all published studies to include one to 28 drinks per week, but in some countries (the range) differed – they were higher in some and lighter in others," Professor Anstey said. "Australian guidelines, for instance, don't say 28 drinks is moderate."


Marijuana prevents cancer?

Proper caution expressed about these results below. Marijuana users may be more middle class, for instance, and that could explain the better health. A balanced evaluation would also look at harms that marijuana might inflict -- such as a greater incidence of paranoid psychosis

Among the more interesting pieces of news that came out while I was on vacation the first half of August was a new study in the journal Cancer Prevention Research, which found that marijuana smokers have a lower risk of head and neck cancers than people who don’t smoke marijuana. Alas, this important research has been largely ignored by the news media.

While this type of study cannot conclusively prove cause and effect, the combination of this new study and existing research — which for decades has shown that cannabinoids are fairly potent anticancer drugs — raises a significant possibility that marijuana use is in fact protective against certain types of cancer.

A team of researchers from several major universities conducted what is known as a “case-control” study, comparing patients who had squamous cell carcinoma of the mouth, larynx, and pharynx with control patients matched for age, gender, and residence location who did not have cancer. By looking at matched groups with and without cancer, researchers hope to find patterns indicating risk or protective factors. In this case they focused on marijuana use, but also took into account known risk factors for this type of cancer, including tobacco and alcohol use.

After adjusting for those confounding factors, current marijuana users had a 48% reduced risk of head and neck cancer, and the reduction was statistically significant. Former users also had a lower risk, though it fell short of being significant. The investigators crunched the numbers several different ways — for example, by amount of marijuana used or the frequency of use — and the findings stayed the same nearly across the board, with moderate users showing the strongest and most consistent reduction in cancer risk.

The scientists write, “We found that moderate marijuana use was significantly associated with reduced risk HNSCC [head and neck squamous cell carcinoma]. The association was consistent across different measures of marijuana use (marijuana use status, duration, and frequency of use).”

Strikingly, among drinkers and cigarette smokers, those who also used marijuana reduced their cancer risk compared to those who only drank and smoked cigarettes. So marijuana may actually have been countering the known bad effects of booze and cigarettes.


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