More on Cortisol, Cognition, and Brain Volume

In my last post, I said stress may not cause Alzheimer's disease, but there is evidence that it aggravates its symptoms.  Causative or not (and it may well contribute to causation), elevated cortisol in urine can predict the onset of Alzheimer's disease about three years before the appearance of symptoms.  This is according to a study published in the journal Neurology in January 2017.

This study was brought to my attention by Carl, a subscriber to this blog.  Carl is a PhD chemist living in California who has been successfully battling MCI due to Alzheimer's disease for several years.  He was a participant in one of the aducanumab trials and has shared a number of insights with me.

The study used participants from the Baltimore Longitudinal Study on Ageing. It involved 1,025 participants who contributed urine samples over an average of 10 and a half years (1 - 31 years).  Ninety-four were diagnosed with Alzheimer's disease during the course of the study.  

Biennially, study participants traveled to their test site and spent 24 hours there.  They collected all urine during the 24 hour period and were subject to a battery of cognitive tests.  This is different from similar studies (including the one in my last post), in that other studies used a single blood or other sample taken in the morning for cortisol measurement.  Presumably, the Baltimore protocol controlled for the influence of stress variation throughout the day.  

I would note that participants were taken out of their normal environments when their samples were taken, and those environments likely contained the sources of their stress.  Also, one peer reviewer noted the difficulty of assigning direct cause and effect, suggesting that more study is needed to more precisely understand the mechanisms at work, as well as the role of other factors.  Other factors included blood pressure, insulin resistance, etc.  The study authors agreed with the comment.

Nevertheless, the researchers believe they found that variation in cortisol levels can predict the onset of Alzheimer's disease.