Interesting study links Liver AST / ALT ratio to AD

[mike]

Very interesting study that links body and brain, and could lead to inexpensive tests for Alzheimer's.

https://www.medpagetoday.com/neurology/ ... DHE_Active

People with elevated AST to ALT ratios were more likely to have an Alzheimer's disease diagnosis (OR 7.932, 95% CI 1.673-37.617; P=0.03) than cognitively normal adults. Increased AST:ALT ratio was also linked to poor cognition, lower CSF levels of the 42-residue form of amyloid-β, increased amyloid-β deposition, higher CSF levels of phosphorylated tau and total tau, and reduced brain glucose metabolism.

Levels of ALT were significantly decreased in Alzheimer's disease patients compared with cognitively normal people (OR 0.133, 95% CI 0.042-0.422; P=0.004). Lower levels of ALT also were associated with increased amyloid-β deposition, reduced brain glucose metabolism, greater brain atrophy, and poor cognition.

Besides ALT levels and AST:ALT ratios, alkaline phosphatase elevations also were significantly associated with poor cognition.

and also

"The significance of these associations is that they underscore the importance of connecting peripheral and central biological processes," he told MedPage Today. "Now that we know they are related, new questions emerge: How do central and peripheral processes evolve over time? How do longitudinal changes in these blood analytes relate to clinical, cognitive, and neural changes? What are the causal directions and pathways? Most importantly, are there medications or lifestyle interventions that influence liver function that might reduce the risk of developing Alzheimer's disease or related dementias?"

and finally

"While we have focused for too long on studying the brain in isolation, we now have to study the brain as an organ that is communicating with, and connected to, many other organs that support its function and that can contribute to its dysfunction," Kaddurah-Daouk told MedPage Today. "Hence, the emerging concept that Alzheimer's might be a systemic disease that affects several organs, including the liver, and that these changes in the body can lead to metabolic problems in the brain needs to be more fully explored."

(my emphasis)

[slacker]

Non alcoholic fatty liver is part of the metabolic syndrome, and often occurs with elevated AST and ALT. So, yes, there is interaction between body parts!

[BrianR]

I was a little frustrated when I couldn't find their specific threshold ALT and AST:ALT levels. I did find this table in the Supplements:

2019 Nho K et al. JAMA Network Open. eTable 2.png

I wondered about the extent to which standard deviations overlapped the means, but I'll the statisticians provide intelligent opinions on that.

[BrianR]

Also, FWIW, low ALT seems to be generally bad for those who are getting older, e.g.:
The Association of Alanine Transaminase With Aging, Frailty, and Mortality
Low Alanine Aminotransferase Levels in the Elderly Population: Frailty, Disability, Sarcopenia, and Reduced Survival
Low ALT blood levels are associated with lower baseline fitness amongst participants of a cardiac rehabilitation program