Carlos Solis
An international team of researchers studied 4,726 volunteers of various ages with healthy brains. Brain scans of the participants revealed “small but systematic sex differences” in patterns of nerve-tissue atrophy.
It’s well known that the human brain naturally shrinks with age. In people who die from Alzheimer’s disease, there is a sharp loss of brain volume.
Alzheimer’s disease is diagnosed in women about twice as often as in men, yet surprisingly little is known about how sex affects brain volume as people age.
What Did the Scientists Discover?
The team found that men’s brains shrink more rapidly with age and show faster loss of gray and white matter than women’s.
“If women’s brains were to weaken more noticeably, it could explain the higher prevalence of Alzheimer’s among them,” said neurobiologist Ann Ravndal from the University of Oslo, a co-author of the study.
Ravndal and her colleagues collected more than 12,500 MRI scans during the study. Each participant had at least two scans spaced about three years apart.
Researchers found that older men exhibited deterioration in a greater number of brain regions, including many parts of the cortex. By contrast, women showed deterioration in fewer areas, and cortical thickness changed less with age.
A faster decline in hippocampal volume appeared only at the oldest ages. That could be tied to longevity differences — women tend to live longer than men.
Separating the effects of sex on the brain from other genetic and environmental factors is challenging, and it’s made harder by the relative shortage of long-term studies.
The findings point to real sex differences in the biology of brain aging, ScienceAlert reported. But the authors cautioned that the results should be interpreted carefully and that more research is needed.
Despite many studies on brain aging in recent years, the field has been marked by a strong sex bias. In 2019, only about 5 percent of published neuroscience and psychiatry research considered sex as a factor.
It still remains unclear whether the degree and speed of brain deterioration differ between men and women.
The study was published in the journal PNAS.
Photo: Unsplash
