How little we know about the role of cholesterol in the human body

I was just discussing cholesterol levels with my husband the other day. He had his levels checked when they drew blood for his A1C test. They had all risen, particularly the HDL. It should be noted that his diet has changed dramatically recently, much more meat, especially red meat and fish.

I question whether cholesterol levels, particularly those for HDL, are at a correct range for the body to run optimally. Coming across this study on cholestrol levels and dementia adds to my curiosity.

RESULTS: Cholesterol levels in men with dementia and, in particular, those with Alzheimer disease had declined at least 15 years before the diagnosis and remained lower than cholesterol levels in men without dementia throughout that period. The difference in slopes was robust to adjustment for potential confounding factors, including vascular risk factors, weight change, alcohol intake, and use of lipid-lowering agents. CONCLUSION: A decline in serum total cholesterol levels may be associated with early stages in the development of dementia.

Conventional Wisdom would tell you that any decrease in cholesterol levels is good. Maybe it's not.