Friday, March 6, 2015

Worried About Getting Alzheimer's Disease?

This is one of Steve's "reflection" photos from a temple in Kyoto.

Everyone thinks about it from time to time.  And it doesn’t help that there is a constant media frenzy to report the latest findings about what might cause or prevent Alzheimer’s.  Unfortunately, much of this information is flawed, the result of poor science or a chance finding.  This is something we want to write about, and maybe occasionally rant.
So we approached the headline of the week:  “An Upside to Gout: It May Offer Alzheimer’s Protection,” from The New York Times ( ) with skepticism.  We read the full published study in the medical journal, Annals of the Rheumatic Diseases, and found it was actually a good and potentially useful article that showed that fewer people with gout developed Alzheimer's over a 10 year period than a control group.   We thought we would talk about what’s good in this study, compared to the usual stuff, to help you in separating the signal from the noise in the media and in these kinds of risk studies.

So what did they do right?

Most studies of this sort that look for risk factors for a disease take a big sample of people and let the computer search through all possible risk factors in the data set.  This shotgun approach increases the likelihood that any findings will be due to chance, and over the years many improbable things have been reported as causing Alzheimer’s disease.

In this study, the researchers had good reasons from the start to look at gout.  Uric acid, which the body overproduces in gout, has anti-oxidant properties that may protect certain types of neurons in the brain from damage.  Damage to these neurons has specifically been implicated in Alzhiemer’s disease and Parkinson’s diseae.  So the idea behind the study was to see if high levels of uric acid might lower risk of Alzheimer’s disease.

Another strength of the study was that instead of comparing gout patients to everyone else in the sample, which could introduce a variety of factors that might account for differences in rates of Alzheimer’s disease, the researchers created a matched control group.  Basically, they found people in the larger study that they drew their sample from who were similar to the gout patients on some key characteristics such as age, gender and a couple other things, and then they statistically controlled for other possible confounding factors such as other illnesses and medications.  This gave the study a nice comparison between people who had gout and people who differed mainly in not having gout.

The main drawback of the study is that they relied on diagnoses of Alzheimer’s disease made by general practitioners, which can be unreliable.  But they did something quite clever.  They conducted what they called a “negative exposure control,” that is, they took people with osteoarthritis and compared their rates of AD over time to a matched control group and found osteoarthritis had no effect on risk of Alzheimer’s disease.  

So what’s the take-home message?  It’s that uric acid or related substances may be protective against Alzheimer’s disease or slow its development.  But it’s too early to rush out and try supplements.  Giving people gout is obviously not a good treatment option.  Other antioxidants have been studied extensively in the past without any clear-cut evidence that they are effective in preventing or treating Alzheimer’s disease.  In time, this may be just another false lead in the search for causes and treatment of Alzheimer's.  For now, the finding is intriguing.

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