In a study from the University of California San Diego, scientists found high levels of an enzyme called PHGDH in the blood of older adults could be an early warning sign of Alzheimer’s disease.
In analyzing brain tissue, they found expression levels of the gene coding for PHGDH were consistently higher in people with different stages of Alzheimer’s disease, even the early stages before cognitive symptoms manifested.
The findings also prompt caution against the use of dietary supplements that contain the amino acid serine as a remedy for Alzheimer’s disease.
Because PHGDH is a key enzyme in the production of serine, the increased PHGDH expression found in Alzheimer’s patients suggests that the rate of serine production in the brain is also increased, and thus, taking additional serine may not be beneficial.
In a previous study, the team identified PHGDH as a potential blood biomarker for Alzheimer’s disease.
The results were promising, and the researchers were curious if this increase could be linked back to the brain. In their current study, they show that this indeed is the case.
The researchers analyzed genetic data collected from post-mortem human brains from subjects in four different research cohorts, each made up of 40 to 50 individuals 50 years and older.
The participants consisted of Alzheimer’s patients, so-called “asymptomatic” individuals (people without cognitive problems and without an Alzheimer’s diagnosis, but whose post-mortem brain analyses showed early signs of Alzheimer’s-related changes), and healthy controls.
The team showed a consistent increase in PHGDH expression among Alzheimer’s patients and asymptomatic individuals in all four cohorts compared to the healthy controls.
Moreover, expression levels were higher the more advanced the disease. This trend was also observed in two different mouse models of Alzheimer’s disease.
The researchers also showed that the worse the cognitive test scores, the higher the expression of PHGDH in the brain.
The findings come with implications for serine supplements, which are advertised to improve memory and cognitive function.
The key player responsible for making serine in the body is PHGDH. Some researchers have proposed that PHGDH expression is reduced in Alzheimer’s disease and that boosting serine intake could help with treatment and prevention.
Clinical trials are already underway to test serine treatments in older adults experiencing cognitive decline.
But with their data consistently showing increased PHGDH expression in Alzheimer’s, the researchers posit that serine production may likely be increased in this disease, contrary to what some other groups claim.
If you care about Alzheimer’s, please read studies about mounting evidence that herpes virus is a cause of Alzheimer’s, and boosting the brain’s cleaning crew to mop up Alzheimer’s disease.
For more information about brain health, please see recent studies that cranberries could help boost memory, and these antioxidants could help reduce dementia risk.
The study was conducted by Sheng Zhong et al and published in Cell Metabolism.
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