Friday, August 17, 2007

Smoking and Alzheimers

I have often seen it claimed that smoking has a protective effect against Alzheimers. That is not what the research literature says, however. Quite the reverse. See the meta-analysis below. Smoking is quite clearly bad for your brain.

Smoking as a Risk Factor for Dementia and Cognitive Decline: A Meta-Analysis of Prospective Studies

By Kaarin J. Anstey et al


The authors assessed the association of smoking with dementia and cognitive decline in a meta-analysis of 19 prospective studies with at least 12 months of follow-up. Studies included a total of 26,374 participants followed for dementia for 2-30 years and 17,023 participants followed up for 2-7 years to assess cognitive decline. Mean study age was 74 years. Current smokers at baseline, relative to never smokers, had risks of 1.79 (95% confidence interval (CI): 1.43, 2.23) for incident Alzheimer's disease, 1.78 (95% CI: 1.28, 2.47) for incident vascular dementia, and 1.27 (95% CI: 1.02, 1.60) for any dementia. Compared with those who never smoked, current smokers at baseline also showed greater yearly declines in Mini-Mental State Examination scores over the follow-up period (effect size (รก) = -0.13, 95% CI: -0.18, -0.08). Compared with former smokers, current smokers at baseline showed an increased risk of Alzheimer's disease (relative risk = 1.70, 95% CI: 1.25, 2.31) and an increased decline in cognitive abilities (effect size (beta) = -0.07, 95% CI: -0.11, -0.03), but the groups were not different regarding risk of vascular dementia or any dementia. The authors concluded that elderly smokers have increased risks of dementia and cognitive decline.

American Journal of Epidemiology 2007 166(4):367-378

Pollution causes four in 10 deaths, survey finds

And you thought that heart disease, cancer, bacteria and viruses were the biggest problems! The "study" reported below is just an exercise in wild assumptions. It would have been more defensible if he had said that politics kills people. Socialist politics certainly keep people poor and the worlds's poor do have less access to things like clean water, good sanitation, adequate nutrition and competent medical services

Some 40 percent of deaths worldwide are caused by water, air and soil pollution, a study has found. Such environmental degradation, coupled with the growth in world population, are major causes of a recent rapid increase in diseases reported by the World Health Organization, said the researcher.

Both factors contribute to the malnourishment and disease susceptibility of 3.7 billion people, added the investigator, David Pimentel of Cornell University in Ithaca, N.Y. The findings appear in the early online issue of the research journal Human Ecology and are slated for publication in the December print issue.

Pimentel and some graduate students examined data from more than 120 published papers on the effects on human disease of population growth, malnutrition and various kinds of environmental degradation. "We have serious environmental resource problems of water, land and energy, and these are now coming to bear on food production, malnutrition and the incidence of diseases," said Pimentel.

Of the world population of about 6.5 billion, 57 percent is malnourished, compared with 20 percent of a world population of 2.5 billion in 1950, he added. Malnutrition is not only the direct cause of 6 million children's deaths each year but also makes millions of people much more susceptible to such killers as acute respiratory infections, malaria and a host of other lifethreatening diseases, according to the research.

Among the other points:

* Nearly half the world's people are crowded into urban areas, often without adequate sanitation, and are exposed to epidemics of such diseases as measles and flu.

* With 1.2 billion people lacking clean water, waterborne infections account for 80 percent of all infectious diseases. Increased water pollution creates breeding grounds for malaria-carrying mosquitoes, killing 1.2 million to 2.7 million people a year, and air pollution kills about 3 million people a year. Unsanitary living conditions account for more than 5 million deaths each year, of which more than half are children.

* Air pollution from smoke and various chemicals kills 3 million people a year. In the United States alone about 3 million tons of toxic chemicals are released into the environmentcontributing to cancer, birth defects, immune system defects and many other serious health problems.

* Soil is contaminated by many chemicals and pathogens, which are passed on to humans through direct contact or via food and water. Increased soil erosion worldwide not only results in more soil being blown but spreading of disease microbes and various toxins.

At the same time, more microbes are becoming increasingly drugresistant. And global warming, together with changes in biological diversity, influence parasite evolution and the ability of exotic species to invade new areas. As a result, such diseases as tuberculosis and influenza are reemerging as major threats, while new threatsincluding West Nile virus and Lyme diseasehave developed.

"A growing number of people lack basic needs, like pure water and ample food. They become more susceptible to diseases driven by malnourishment, and air, water and soil pollutants," Pimentel concluded. He and his coauthors called for comprehensive and fair population policies and more conservation. "Relying on increasing diseases and malnutrition to limit human numbers in the world diminishes the quality of life for all humans and is a highrisk policy," they wrote.



Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.


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