Depression, dementia and brain glucose

Depression and dementia, including Alzheimer's disease, are strongly affected by brain glucose and insulin regulation. A study just published in the journal Psychiatry Research: Neuroimaging presents evidence that brain glucose dysregulation is a modifiable risk factor for both depression and dementia/Alzheimer's disease in later life. The authors state:

"Evidence exists for late-life depression (LLD) as both a prodrome of and risk factor for Alzheimer’s disease (AD)...Impaired peripheral glucose metabolism may explain the association between depression and AD given the connection between type 2 diabetes mellitus with both depression and AD."

Furthermore...

"Positron emission tomography (PET) measures of cerebral glucose metabolism are sensitive to detecting changes in neural circuitry in LLD and AD."

So they correlated fasting serum glucose (FSG) levels in non-diabetic young (YC) and elderly controls (EC) and late-life depression patients with PET scans of cerebral glucose metabolism. There was indeed an association of brain dysglycemia with depression and dementia:

"The negative correlations were more extensive in EC versus YC and in LLD patients versus EC. Increased FSG correlated with decreased cerebral glucose metabolism in LLD patients to a greater extent than in EC in heteromodal association cortices involved in mood symptoms and cognitive deficits observed in LLD and dementia. Negative correlations in YC were observed in sensory and motor regions."

In other words, increased serum glucose with cerebral insulin resistance (hence decreased brain glucose metabolism) correlated with both depression and cognitive deficits. The authors conclude:

"Understanding the neurobiological consequences of diabetes and associated conditions will have substantial public health significance given that this is a modifiable risk factor for which prevention strategies could have an important impact on lowering dementia risk."

See earlier posts on insulin resistance, dysglycemia (glucose dysregulation), HgbA1c and brain health.