A new study published in JAMA found that a Klotho gene variant positively impacts the risk of Alzheimer’s disease in people who carry the APOE E4 variant.
This is good news for a lot of people who carry the APOE E4 allele — and it also points to ways that we can all modify our lifestyle to increase or protect Klotho levels as we age.
Alzheimer’s, APOE, and KLOTHO:
Quick APOE and Alzheimer’s overview:
APOE is a glycoprotein that binds to lipids (fats) and helps transport cholesterol. It is especially important in the brain, where it is produced by astrocytes and moves cholesterol to the neurons.
There are three common forms of APOE, known as E2, E3, and E4.
People who carry the APOE E4 allele are at a higher risk of late-onset Alzheimer’s disease. In fact, this is the most well-studied variant for Alzheimer’s, with hundreds of studies on it over the last few decades. Importantly, though, the APOE E4 allele is not sufficient by itself to cause Alzheimer’s. While carrying two copies of the E4 allele is linked with a very high rate of Alzheimer’s, people carrying two copies can live to their 90s without dementia. Similarly, many people without the APOE E4 allele succumb to this terrible disease.
Researchers have questioned why the APOE E4 allele is such a huge risk factor for some people but yet not a complete cause of Alzheimer’s. They have investigated it from many angles– lifestyle factors, diet, toxins, infectious diseases, and more. And all of these seem to play some sort of a role in the risk of Alzheimer’s.
Klotho is a protein linked to longevity and cognitive function. It is named after the Greek goddess Clotho, one of the Three Fates who was the spinner of the thread of life.
The klotho protein was originally identified in mice who carried a mutation that caused accelerated aging. These mice were found to have a loss of function mutation in the klotho gene, which caused atherosclerosis, osteoporosis, muscle loss, kidney disease, and sagging skin – starting at 3 to 4 weeks of age. Likewise, creating a mouse strain that overexpresses the klotho gene causes a longer lifespan.[ref][ref] This holds true for humans and other mammals as well, with lower klotho levels linked to the signs and diseases of aging and klotho levels generally decreasing with age.
The klotho protein is found on the membrane of cells in specific parts of the kidneys and in the brain. In the kidneys, klotho regulates phosphorous and calcium levels and also acts as a co-receptor for fibroblast growth factor receptors. Specifically, Klotho interacts with the fibroblast growth factor 23 (FGF23) to increase phosphate excretion and suppress vitamin D synthesis.[ref] Basically, when the diet is high in phosphate, klotho causes lower active vitamin D (1,25 OH-D).[ref]
Within the brain, the choroid plexus region produces the most klotho protein. The choroid plexus is the area in the brain ventricles that produces cerebrospinal fluid, which is vital for removing metabolic waste and other toxins from the brain. Researchers have found that within the choroid plexus, klotho helps suppress brain inflammation by modulating vitamin D activation.[ref]
The latest research on how Klotho Variants affect Alzheimer’s:
I will try to explain the recent study in the Journal of the American Medical Association (JAMA) more thoroughly.[ref]
The 24,000+ study participants were 60 years of age or older and Caucasian. Researchers looked at both APOE status and KLOTHO variants to see if there was an interaction with the risk of Alzheimer’s. The researchers used both population data, measures of amyloid-beta 42 in the cerebrospinal fluid, and brain imaging in the study. The study participants were grouped by APOE type (E4 allele carriers and non-E4 carriers) and evaluated across three age ranges (age 60+, age 60-80, and age 80+)
The results of the study showed that people with the APOE E4 allele were at an increased risk of Alzheimer’s, which is in line with all the other hundreds of studies on the gene.
However, people with both the KLOTHO VS variant and the APOE E4 type were at less of an increased risk.
In fact, carrying the KLOTHO VS variant reduced the risk of Alzheimer’s for APOE E4 carriers by 30% compared with E4 carriers without the KLOTHO variant. Additionally, the researchers found that PET scans showed decreased amyloid-beta in those who were both APOE E4 positive and carried the KLOTHO VS variant.
You may wonder why the study only used heterozygous people (carried one copy) for the KLOTHO VS variant. I think it is due to the small percentage of the population that carries two copies of the variant. While up to 25% of most population groups have one copy of the KLOTHO VS variant, less than 5% carry two copies. Considering how that would combine with the 20% of the population carrying APOE E4 alleles, there would be a very small number who carry both copies of the KLOTHO VS variant and the APOE E4 allele.
This study further confirms the results of a 2019 study where the KLOTHO VS variant was also found to help mitigate the increased risk of the APOE E4 allele. The previous study was quite small but showed similar results for risk and amyloid-beta reduction.[ref]
Klotho Genotype Report:
Lifehacks for boosting Klotho:
A variety of diet and lifestyle factors influence your risk of Alzheimer’s disease, and changes to your diet and lifestyle can help to prevent Alzheimer’s. Check out the full article on APOE variants for lots of prevention suggestions.
What about boosting Klotho levels? While no specific studies are showing that boosting klotho levels in people with APOE E4 will modify Alzheimer’s risk, it follows that increasing klotho may help and shouldn’t hurt.
Diet, Supplements, and Exercise to Increase Klotho
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