September 22, 2007

Extremely Bad Science: Depression & Type 2

Here's a study that is a "perfect storm" of bad science. Unfortunately, as you can see from the way the media report is titled, the findings are being presented by the media in a way that suggests people with Type 2 have mental problems, though, in fact, the study is so badly flawed as to be worthless.

Here's one version of the media coverage:

EASD: Studies Link Depression and Type 2 Diabetes

From the article: "Type 2 diabetes may be linked to mental health disorders, but age and gender may be contributing factors, according to two separate studies.

"Symptoms of depression or psychological stress were associated with increased risk of type 2 diabetes in men, but not in women, Swedish researchers reported

Why is this bad science? Two reasons.

1. The symptoms of "depression" used to compute the amount of depression in the study subjects included "sleep difficulties, apathy, anxiety, depression, fatigue, and back or shoulder pain during the preceding 12 months." [emphasis mine]

Anyone who knew anything about diabetes would immediately note that "back and shoulder pain" can be caused by a lot of other things besides depression. Like, for example, the tendon and disc problems associated with abnormally high blood sugars.

It is now known that carpal tunnel syndrome develops about 10 years before people receive a diagnosis of diabetes and may indicate the presence of high post-meal blood sugars that are missed by the fasting plasma glucose test used for diagnosing diabetes.

It is also known that Frozen Shoulder is much more common among people with diabetes and it too is probably caused by high blood sugars which thicken tendons. I recently read in the book Sciatica solutions : diagnosis, treatment, and cure for spinal and piriformis problems by Dr. Loren Fishman that some specialists believe that vertebral disc problems may be caused by blood sugar abnormalities.

So my conclusion--and that of anyone familiar with diabetic tendon problems--would be that people who have diabetes or undiagnosed diabetes who also have back and shoulder pain probably have physiological back and shoulder problems caused by high blood sugars, NOT psychosomatic symptoms caused by depression. And diagnosing them as depressed based on this laundry list of vague symptoms is a mistake.

2. The second problem here, a major one, is that we know that some of the powerful psychiatric drugs given--often very inappropriately--to people who complain of mild depression can cause diabetes. Zyprexa is only one of these, the best known, but the other drugs commonly used may also affect glucose metabolism.

However, the article states that these studies did NOT identify patients who had been treated for depression with these drugs that can destroy blood sugar control. Hence the association of "depression" with diabetes is worthless. Yes, inappropriate drug TREATMENT for depression may CAUSE diabetes, but this is not the conclusion being drawn here, that somehow, having Type 2 diabetes makes people more depressed.

How do people get media attention for such poorly conducted research? These studies wouldn't get an "A" at a well conducted high school science fair! But it still got international media attention and you can bet that a lot of doctors are going to only read the headline and conclude that depression and diabetes go together.

It DOES depress me to see yet another example of the lousy science that hurts people with diabetes, just as it depresses me to see the rotten treatment so many people with diabetes get.



If not a mother... said...

I think it's unfortunate that this study is being twisted round and round.

Seasonal affective disorder can lead to carb cravings. In a big way. I'm living proof. Not to mention that I'm sure anxiety can mess with metabolism, too. (I know it definitely messes with blood pressure.)

I think there does need to be more research into mental health issues and how they relate to type 2 diabetes. I am curious whether the genetic link in type 2 diabetes starts out as a genetic link in anxiety & depression. It appears to be that way in my own family, anyways.

Unknown said...

Wasn't there a study about feeding junk food to mice? Only the mice under stress gained weight.

I had wondered what quiting smoking had to do with accelerating my weight gain, not just the initial gain where I was substituting food for the habit, but all the years since. It just dawned on me the other day, my doctor had to double my antidepressant dose and add a temporary tranquilizer a few weeks into my trying to quit.