DSeid, you’re totally helping with that reminder. We only really learn the facts when we keep in mind the logical fallacies that can lead us astray.
More and more, I’m aware that what we think of as different systems - central nervous system, respiratory system, immune system, endocrine system - are far more interconnected than we ever knew. Bone cells talk to fat cells. Genes are turned on and off by environmental stressors. A person with a genetically identical twin has a 50% chance of developing Type I diabetes if their twin has it, but a 90% chance of developing Type II diabetes if their twin has it. Type I is without a doubt an autoimmune disease. Type II? We’re still trying to figure it out. We know it has correlations to mood, environment, job type, genetics, high blood pressure, high cholesterol, race, and geography.
I can see where already having symptoms of MDD could cause a higher incidence of Type II diabetes. Classic symptoms of MDD include hypersomnia (not burning calories), loss of interest in activities (not burning calories), and a change in appetite (often taking in more calories).
But I can’t help but wonder if there isn’t an initial immune reaction to an infection - especially viral, like influenza - that causes sickness behavior, which then is increased by some immune dysregulation, and becomes depression. What, though? An inability to produce immune moderating cytokines? A heightened sensitivity to immune stimulating cytokines? An underlying food allergy, sensitivity, or intolerance that causes chronic inflammation?
I know at this point that I do not have Rheumatoid Arthritis. The autoimmune blood panel I had done indicated a positive anti-nucleus antibody (lab talk for “why, yes, your immune system does seem to be wonky”), but nothing else was positive. After the course of prednisone, the joint and muscle pain and exhaustion faded, but it will come back as soon as I eat any gluten, and it likes to bring suicidal ideation with it. Currently, my symptoms point more towards Sjogren’s than anything else, but I just figured out that my diet has been extremely deficient in protein the past few months.
There are no quick answers. Most studies are predicated on only one or two variables, because following more variables complicates things beyond what researchers can track. There are a couple of on-going, extremely long term studies still under way - one on nurses, and one on people in a specific town - that have already provided a goldmine of information. I suspect what we really need to do is expand our research to larger populations over longer periods of time, and I hope the ubiquity of technology will make that possible.