Key points:
- Treating aged mice with the anti-aging protein klotho improves their spatial and short-term memory.
- Klotho and cognitive stimulation activate overlapping metabolites in young mice, suggesting that klotho mimics cognitive stimulation.
Klotho was named after one of the Fates, the Greek goddess Clotho, who spins the thread of life. It was named so by scientists because mice without klotho age faster and have shortened lifespans. Furthermore, humans with higher levels of klotho tend to live longer. Now, what if this protein could mimic the benefits of cognitive stimulation, which is associated with a reduced risk of Alzheimer’s?
Gupta and colleagues from the University of California, San Francisco report in the Journal of Neuroscience that treating mice with klotho mimics the metabolic changes associated with cognitive stimulation and counters age-related cognitive deficits.
Klotho Improves the Memory of Aged Mice
To test the effect of klotho on the cognitive performance of aged mice, Gupta and colleagues subjected aged mice to the Y maze, a test for measuring spatial and short-term memory. Investigators found that 22-month-old mice (equivalent to about 70 human years) injected with a mouse variant of klotho (mKL1) were more apt to explore new areas of the maze compared to untreated aged mice, suggesting that klotho improves the spatial and short-term memory of aged mice.
To determine which metabolites are activated in response to cognitive stimulation, Gupta and colleagues removed the brains of young mice (4 months old, equivalent to 26 human years) after completing the Y-maze test to analyze the genes activated in their hippocampus — the brain region that consolidates memories. Compared to non-cognitively stimulated mice, which were mice placed into an ordinary cage before brain harvesting, cognitively stimulated mice had altered metabolite levels. Several of these metabolites are known to decrease with aging and are associated with neurodegeneration.
To examine the effect of klotho on these metabolites, mice were injected with a long (KL) or short (KL1) variant of the klotho protein. It was found that several of the metabolites altered by KL and KL1 overlapped with the metabolites altered by cognitive stimulation. A total of six metabolites overlapped between all three groups. Thus, the data suggest that in the absence of cognitive tasks, klotho causes metabolic alterations that partially mimic a cognitively stimulated brain.
Overall, the findings of Gupta and colleagues suggest that klotho can improve the cognitive performance of aged mice and mimic cognitive stimulation in young mice. The implications of these findings allude to klotho as a potential cognitive enhancer for both the young and old. However, klotho has not yet been tested for this purpose and is not available in supplement form.
Why Care about Klotho?
Low klotho levels have been associated with a 31% higher risk of death in American adults aged 40 to 79 years. Additionally, individuals within the same age range who suffer from metabolic syndrome were observed to have low klotho levels. Furthermore, previous studies have shown that low klotho levels are associated with cardiovascular and kidney disease.
While klotho research hasn’t reached the clinical stage, there are some recent studies showing how it can be boosted. Although still under peer review, an analysis of 12 studies showed that 621 individuals ranging from the ages of 30 to 65 had increased levels of klotho after 12 weeks of exercise, regardless of their health condition. This would suggest that klotho levels can be boosted by regular exercise, possibly enhancing cognitive performance. Indeed, another analysis of several studies showed that increasing klotho with aerobic exercise is associated with improving cognition in Alzheimer’s patients.
In addition to exercise, a Mayo Clinic study showed that a combination of dasatinib and quercetin, which are senolytic compounds, boost klotho levels in aged and obese mice. Moreover, a recent study showed that a molecule called berberine, which has been shown to extend the lifespan of fruit flies and mice, also raises klotho levels in aged mice and protects the heart against age-related damage. Since senolytics, berberine, and exercise all slow down the aging process and raise klotho levels, it would seem that klotho was appropriately named.
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