Muscle discovery, aging and memory, and other stories

Muscle discovery may lead to better drugs

The smallest components of muscle, myosin and actin, could be targeted to contribute to more effective treatments for heart and muscle diseases, says a group of international researchers from McGill University and Linnaeus University.

The question of what happens at the molecular level in our muscles when they are activated has long eluded researchers. In muscles there are billions of small proteins called myosin and actin. They are only a hundred thousandths of a millimeter in size individually, but these microscopic units generate kinetic energy by converting cellular fuel into phosphate, among other things. But how exactly this works has long been a mystery.

“We mapped how phosphate, the substance that forms when muscles are activated, behaves when released from myosin during muscle contractions,” says Dilson Rassier, dean of the Faculty of Education and lead author of the study. “The phosphate moves differently than previously thought and makes several ‘breaks’ in and on the myosin.”

“Our results have great potential importance for the treatment of serious diseases in which myosin plays a central role. This applies to serious diseases of the heart and body muscles, to the spread of cancer cells into new tumors, and to the invasion of human red blood cells by malaria parasites,” says study co-author Alf Månsson, professor of physiology at Linnaeus University.

“Multistep orthophosphate release tunes actomyosin energy transduction” by Luisa Moretto et al. was published in nature communication.

Faster cognitive decline in older adults with low muscle mass?

McGill University researchers have found for the first time a significant association between having low muscle mass and faster cognitive decline, and that this association is independent of muscle strength and level of physical activity. According to the researchers, these results could help identify people at risk of developing dementia.

The research is based on examining a cohort of 30,000 Canadians between the ages of 65 and 86. Researchers from the McGill School of Human Nutrition and the Metabolic Disorders and Complications Program (MeDiC) at the McGill University Center for Health Research Institute (RI-MUHC) have shown for the first time that having less muscle mass is associated with faster cognitive decline in older adults.

“These findings are important because muscle mass is a modifiable factor, which means we can do something about it. Exercise – especially resistance training – and a good diet with enough protein can help maintain muscle mass for years,” says Stéphanie Chevalier, who led the study. “Our results show that measuring low muscle mass can help identify people who are at higher risk for cognitive decline. We should measure muscle mass more broadly, in clinics, not just in research studies.”

Association of Low Muscle Mass With Cognitive Function During a 3-Year Follow-up Among Adults Aged 65 to 86 Years in the Canadian Longitudinal Study on Aging, by Stéphanie Chevalier et al., was published in JAMA network open.

One step closer to understanding the impact of aging on memory in older adults

Aging is often associated with memory loss in healthy adults of midlife and old age. However, it is not age itself that contributes to memory deterioration, but rather the effects of age on the volume of the hippocampus, an important brain component that helps consolidate information from short-term memory into long-term memory, which are likely to affect memory performance.

A team of McGill researchers is studying how certain brain structures change throughout life and how this affects memory function. Understanding how normative aging affects brain structure, function, and cognition is critical to establishing a ground truth, or baseline, that can be used to identify early signs of pathological aging associated with diseases such as Alzheimer’s and Parkinson’s.

The team worked with a sample of 125 healthy adults aged 19 to 76 who were asked to perform memory tasks. The researchers found that the ability to recall detailed face-location associations was associated with larger volumes in the posterior hippocampus and medial temporal system, and that normative aging was associated with reduced volumes in these brain regions and associated deficits in memory function was.

They also found that age-related reductions in volume in the posterior hippocampus correlated with reduced activity in brain networks important for perception, memory and cognitive control. The results show how memory depends on the interaction of multiple brain networks and how normative aging affects these brain systems and cognition.

“We were surprised that our results were so specific and unambiguous. This is rare in neuroscience and speaks for the robustness of the methods and results,” says Maria Natasha Rajah, professor at the Department of Psychiatry and senior author of the study.

Researchers around the world have long attempted to understand differences between normative and pathological aging in order to best identify indicators of age-related neurodegenerative diseases. “We hope that our work will help advance the understanding of memory and brain deficits in aging and dementia,” Rajah added.

“The volume of the posterior hippocampus mediates age-related differences in spatial context memory and correlates with increased activity in lateral frontal, parietal, and occipital regions in healthy aging” by Jamie Snytte et al. was published in NeuroImage.

About McGill University

Founded in 1821 in Montreal, Quebec, McGill University is Canada’s premier medical doctoral university. McGill is consistently ranked as one of the top universities both nationally and internationally. It is a globally recognized higher education institution with research activities spread across three campuses, 11 faculties, 13 professional schools, 300 degree programs and over 39,000 students, including more than 10,400 doctoral students. McGill attracts students from over 150 countries around the world, its 12,000 international students make up 30% of the student body. Over half of McGill students report having a first language other than English, including approximately 20% of our students who say French is their first language.