A brain chemical blamed for mental decline in old age could hold key to its reversal

February 6, 2018 by Dana Smith, University of California, San Francisco
A brain chemical blamed for mental decline in old age could hold key to its reversal
Credit: University of California, San Francisco

It's a fact of life, for lifeforms big and small, that the mind declines with age. Now researchers at UC San Francisco have identified the buildup of one brain chemical as a key culprit behind age-related learning and memory impairments. Tuning levels of this chemical in the worm C. elegans, they could delay and even reverse the declines of old age.

For C. elegans, a tiny worm that lives only about two weeks, old age and its handicaps come fast – which makes them a convenient model for studying aging. A seven-day old worm has only five percent of the learning capacity of a one-day old worm.

"You look at a person, a fly, a mouse, and a worm. They all look very different from each other, of course. But the amazing thing is the basic building blocks turn out to be the same," said Kaveh Ashrafi, Ph.D., a professor of physiology and member of the UCSF Weill Institute for Neurosciences, who led the new research.

In both C. elegans and humans, the chemical kynurenic acid (KYNA) accumulates with age. As it builds up, KYNA interferes with the activity of glutamate, a essential for learning and memory. In humans, it has previously been linked to neurodegenerative disorders, including Alzheimer's and Parkinson's disease.

In the study published Jan. 31, 2018, in Genes and Development, researchers looked at the effect of KYNA on the ' ability to learn an association between a neutral smell and food.

The researchers found that by keeping KYNA levels low throughout the worm's life, they could prevent the onset of age-related decline – the worms kept learning. In older worms already impaired, lowering KYNA levels could counteract the impairments – raising hope that interventions later in life may be effective in reversing neurological decline.

The reason that KYNA increases with age is still a mystery, but the new study offers an intriguing hint, by linking KYNA buildup in aging worms to elevated levels of insulin, a hormone that controls blood sugar in both worms and humans. In contrast, earlier experiments by Ashrafi's team had found that fasting, which has been linked to longevity, reduced levels of KYNA in worms and improved learning and memory.

Ashrafi thinks that KYNA is the linchpin through which fasting makes the brain better at learning, while aging makes it worse. "These are two sides of the same coin," he said.

Explore further: Researchers find chemical switch that may decrease symptoms of schizophrenia

More information: Mihir Vohra et al. Kynurenic acid accumulation underlies learning and memory impairment associated with aging, Genes & Development (2018). DOI: 10.1101/gad.307918.117

Related Stories

Researchers find chemical switch that may decrease symptoms of schizophrenia

February 7, 2017
A new study by University of Maryland School of Medicine researchers has found that in mice, adjusting levels of a compound called kynurenic acid can have significant effects on schizophrenia-like behavior. The study appeared ...

New gene variant may explain psychotic features in bipolar disorder

March 5, 2013
Researchers at Karolinska Institutet in Sweden have found an explanation for why the level of kynurenic acid (KYNA) is higher in the brains of people with schizophrenia or bipolar disease with psychosis. The study, which ...

Flashing neurons in worms reveal how the brain generates behavior

October 4, 2017
The 100 billion neurons of the human brain control our behavior, but so far there is no way to keep track of all that activity, cell by cell. Whole-brain imaging techniques like fMRI offer only a blurry view of the action, ...

Drug could stop marijuana cravings

October 14, 2013
(Medical Xpress)—In the US, more people seek treatment for marijuana abuse than for abuse of cocaine or heroin. However, there are no approved treatments for marijuana addiction. Robert Schwarcz of the University of Maryland ...

Recommended for you

Wiring diagram of the brain provides a clearer picture of brain scan data

December 14, 2018
Already affecting more than five million Americans older than 65, Alzheimer's disease is on the rise and expected to impact more than 13 million people by 2050. Over the last three decades, researchers have relied on neuroimaging—brain ...

Scientists identify method to study resilience to pain

December 14, 2018
Scientists at the Yale School of Medicine and Veterans Affairs Connecticut Healthcare System have successfully demonstrated that it is possible to pinpoint genes that contribute to inter-individual differences in pain.

Parents' brain activity 'echoes' their infant's brain activity when they play together

December 13, 2018
When infants are playing with objects, their early attempts to pay attention to things are accompanied by bursts of high-frequency activity in their brain. But what happens when parents play together with them? New research, ...

In the developing brain, scientists find roots of neuropsychiatric diseases

December 13, 2018
The most comprehensive genomic analysis of the human brain ever undertaken has revealed new insights into the changes it undergoes through development, how it varies among individuals, and the roots of neuropsychiatric illnesses ...

Researchers find the cause of and cure for brain injury associated with gut condition

December 13, 2018
Using a mouse model of necrotizing enterocolitis (NEC)—a potentially fatal condition that causes a premature infant's gut to suddenly die—researchers at Johns Hopkins say they have uncovered the molecular causes of the ...

Researchers discover abundant source for neuronal cells

December 13, 2018
USC researchers seeking a way to study genetic activity associated with psychiatric disorders have discovered an abundant source of human cells—the nose.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.