So then I found this paper, which discusses Alzheimer's and insulin, and suggests rosiglitazone as a possible treatment:
And here's how that worked:
And that's pretty amazing, considering it has been my understanding that there are no effective treatments for Alzheimer's. A successful prediction is also the gold standard of scientific evidence. Unfortunately, the floor fell through on rosiglitazone:
More circumstantial evidence shows up in the fact that coffee, known to improve insulin sensitivity, is correlated with a reduced risk of Alzheimer's:
And the kicker is this paper from 2005...
"Impaired insulin and insulin-like growth factor expression and signaling mechanisms in Alzheimer's disease - is this type 3 diabetes?"
So now we know where the NYT got its headline. And this may not be as loony as I originally thought. Are they right? Well, we thought we had Alzheimer's figured out about four different times now. First it was choline, then it was amyloid plaques, then it was tau phosphorylation, then it was aluminium toxicity, now it's insulin resistance.
This has the potential to be extraordinary, but I'm not holding my breath.
Known? I've seen interventional studies on the effects of caffeine claiming effects in either direction. Here are two studies showing decreased insulin sensitivity:
Effects of Coffee Consumption on Fasting Blood Glucose and Insulin Concentrations (http://care.diabetesjournals.org/content/27/12/2990.full)
Caffeine Impairs Glucose Metabolism in Type 2 Diabetes (http://care.diabetesjournals.org/content/27/8/2047.extract)
>Higher habitual coffee consumption was associated with higher insulin sensitivity (1) and a lower risk for type 2 diabetes (2–6) in diverse populations. In contrast, short-term metabolic studies showed that caffeine intake can acutely lower insulin sensitivity (7–9) and increase glucose concentrations (10–15). Randomized intervention studies are needed to examine whether tolerance to these acute effects develops after longer-term consumption (16). We therefore examined the effects of coffee and caffeine on fasting blood concentrations of glucose and insulin over 2–4 weeks in two crossover studies in healthy volunteers.
So caffeine causes a problem, but something in coffee, possibly not caffeine itself ( http://ajcn.nutrition.org/content/84/4/682.short ), has a long-term protective effect. Weight control doesn't seem to explain everything: coffee has a protective effect even when consumption is associated with higher BMI ( http://www.sciencedirect.com/science/article/pii/S0140673602... ). In the latter study: "Higher coffee consumption was associated with male sex, a low educational level, a higher body-mass index, cigarette smoking, alcohol use, less leisure time physical activity, and a generally less favourable diet" -- these are not things I would expect to be good for diabetes prevention! Yet the coffee consumers got less diabetes.
Chlorogenic acid, rather than caffeine, seems a likely culprit. Other antioxidants in coffee may play a role.
Regardless of the fact that it's written by a man who resigned from the NYTimes because of plagiarism, it's still interesting imo.
The gist is: the body is complex, so complex that often research mistakes causality with a simple accumulation of facts.
Keep holding your breath.