Brain-boosting benefits of exercise can be passed on to children through sperm, study suggests

Exercise led to build up of molecule in sperm of mice, making offspring better able to learn

Extra-genetic information passed on could help prepare offspring for a more challenging environment (Getty/iStock)

Parents may be able to set their offspring up with a head start in life by exercising, researchers say, after a study found the sperm of fitter fathers carry higher levels of a molecule which boosts learning ability.

Exercise improves brain function and memory, and lowers the risk of neurological conditions, like Alzheimer’s disease, in part because it increases the growth of connections between neurons in the brain.

Now German researchers have identified that “microRNA” molecules which are known to promote this neuron connectivity build up in the brain, and also in the sperm, in response to exercise.

The offspring of male mice who had been made to exercise more and passed on more of these microRNA molecules were better at learning tests and had brains which formed many more neuron connections, known as synapses.

“Presumably, they [the microRNA molecules] modify brain development in a very subtle manner, improving the connection of neurons,” said Professor André Fischer from the German Centre for Neurodegenerative Diseases.

“This results in a cognitive advantage for the offspring,” he added.

While it’s not clear if this applies in humans, it would make sense to have an evolutionary adaptation to better prepare the next generation for being born into a more complicated and challenging environment.

In this case parents who need to work harder to find food and stay alive would likely have higher levels of fitness.

The findings, published today in the journal Cell Reports, add another challenge to a simplistic view of genetics which argues the information passed on to our offspring is not influenced by our environment and experiences.

Recent studies have shown factors like malnutrition, stress and trauma can impact the next generation, for example leaving them at an increased risk of disease.

However, this is the first time that these lived experiences have been linked back to individual microRNA molecules which can be passed on to the next generation.

Various factors of the lives parents live could be encoded in other parts of the RNA, essential genetic information which enables the DNA recipe to be read as well as turning different genes on and off in response to our environment.

While it’s not clear if this mechanism or microRNA markers also affect learning in humans, understanding this phenomenon could give insights into human disease and development.

The authors said: “The accumulating evidence that sperm RNA content encodes information about environmentally induced phenotypic traits is an issue that not only needs to be considered in reproductive medicine, but may also offer the chance to discover biomarkers for complex diseases.”

Other scientists, not involved with the study, said the findings were intriguing and add to the growing evidence that environmental effects can be inherited though it leaves “major questions unanswered”.

Dr Jon Houseley, principal investigator in epigenetics at The Babraham Institute, said it was “intuitive” that information about the environment should be passed on genetically, but this “doesn’t fit with the classical model” of genetic inheritance and remains controversial.

“Nonetheless, this work adds to accumulating evidence that epigenetic inheritance mechanisms are active and important in mammals

“It seems unlikely that these particular RNA molecules will also communicate environmental information across generations in humans, however understanding such inheritance mechanisms in mice suggests ways in which environmental information may be passed to our own children.”

Marcus Pembrey emeritus professor of paediatric genetics at UCL Great Ormond Street Institute of Child Health, said: “If this system of the offspring inheriting a ‘head start’ applies to humans, it might help to explain the so-called Flynn effect where the population IQ in industrial societies has risen every decade for the last century.”