> Please show me a study which demonstrates caffeine's neurotoxicity in humans if you're going to make a claim like that. I can only find ones exploring neurotoxicity in rats and at some pretty high doses.

> Nicotine has only been found to be neurotoxic in adolescents or in extremely high doses. At the normal rate of consumption, it acts as an anti-oxidant and has a protective effect on the brain.

That's exactly my point. Just because something is a neurotoxin for some animals, or at extremely high doses, does not mean that it's actually dangerous. I wasn't trying to make caffeine or nicotine sound dangerous; I was pointing out that looking at some research, seeing "neurotoxic", and being scared is a bad way of approaching science.

Obviously, there are dangers in alcohol consumption. Alcohol has a fairly narrow range between the effective dose (the dose at which you start noticing any effects), and a dangerous dose. There are the obvious cognitive impairments while you are drinking, and some slight longer term impairment (that is much worse for heavy drinkers, and even worse for people who were heavy drinkers and then quit). But there are also advantages. There are some physical advantages to alcohol consumption, related to heart disease. There are the obvious social advantages, which many people cite as the reason they drink. And looking at all-cause mortality, the advantages appear to outweigh the disadvantages, at least for moderate drinkers.

> What if people who choose to drink in moderation just happen to be more likely to do everything else in moderation too? What if people who choose to abstain are more likely to fall into extremes and affect their life span that way? What if someone who moderates everything else and chooses not to drink is healthier than the moderate drinkers?

There is also this study: http://while-science-sleeps.com/pdf/628.pdf which discusses the weaknesses in previous studies, and attempts to correct for them. They look at a quite wide range of potential factors that might be correlated with abstention and increase mortality. The findings are somewhat surprising: in this study, even heavy drinkers had a lower mortality rate than teetotalers. And these effect were still present, though diminished, even once they controlled by many compounding factors.

It does admit that:

> In fact, in tests of potential covariates, we found among these older adults that at baseline, abstainers were significantly more likely to have had prior drinking problems, to be obese, and to smoke cigarettes than moderate drinkers and significantly higher than moderate drinkers on health problems, depressive symptoms, and avoidance coping. Moreover, at baseline, abstainers were signiﬁcantly lower than moderate drinkers on SES, physical activity, number of close friends, and quality of friend support and signiﬁcantly less likely to be married than moderate drinkers. Moreover, all of these covariates signiﬁcantly predicted mortality.

However, it goes on to state:

> Controlling for age and gender, all eleven additional covariates, and the gender-marital status and gender-avoidance coping interactions in the Cox proportional hazards regression analysis reduced the 20-year mortality risk for abstainers compared to moderate drinkers. After including all covariates, the relative mortality risk for abstainers compared to moderate drinkers dropped by close to one-third and approached that of heavy drinkers. However, even after adjusting for all covariates, abstainers and heavy drinkers continued to show increased mortality risks of 49 and 42%, respectively, compared to moderate drinkers. After adjusting for all covariates, the relative risk for light drinkers compared to moderate drinkers was no longer significant.

Now, this study was for older adults (who were 55 to 65 at the beginning of the 20 year study). It discusses in some detail the weaknesses that it has, such as the possibility that it has selected for people who have survived higher levels of drinking. However, it did a very good job of controlling for a lot of compounding factors; and it still found that people who drank had lower mortality rates than people who abstained.