Study Reveals Growing Brain Connectivity Differences Between Sexes with Age
Recent research indicates that certain sex differences in brain connectivity become more significant as people age.
Analyzing brain-imaging data from individuals aged 8 to 100, scientists found that while early life shows minimal differences between male and female brain connections, these disparities expand significantly at puberty. Some of these differences continue to increase throughout adulthood. This study is currently available as a preprint on bioRxiv and hasn’t undergone peer review yet.
This research might shed light on why men and women exhibit different susceptibilities to certain mental health issues, possibly informing treatment approaches. For instance, women are about twice as likely as men to experience anxiety or depression, whereas boys are roughly four times more likely to be diagnosed with autism spectrum disorder than girls.
Amy Kuceyeski, a computational neuroimager at Weill Cornell Medicine in Ithaca, New York, expressed excitement over the study, noting it is unique in examining how sex differences in brain networks evolve over time.
Nevertheless, some neuroscientists are skeptical. They argue that the differences observed in male and female brains may not solely be due to biological sex, pointing out that the study fails to address the impact of gender roles, which are recognized as significant in exploring brain health and disease.
Daphna Joel, a neuroscientist at the University of Tel Aviv, emphasized that human brains don’t fit neatly into ‘female’ or ‘male’ categories. According to a 2015 study she co-authored, each brain is a mosaic, featuring traits that may be more frequent in one sex or the other.
Exploring Sex Differences Throughout Life
In their investigation, Kuceyeski and her team aimed to uncover sex-linked variations in brain development using functional magnetic resonance imaging data from 1,286 individuals, evenly split between men and women. The scans offered a snapshot of each participant’s brain age, rather than following the same individuals over time. They focused on the sex assigned at birth because they lacked data on participants’ gender identities.
Employing a specialized artificial-intelligence tool named Krakencoder, they examined structural and functional differences in brain networks. The analysis revealed sex-linked differences in both types of brain connections: functional differences were more pronounced in higher-order networks responsible for complex cognitive functions, while structural differences peaked in midlife and continued diverging with age, particularly in lower-order networks that manage sensory information.
Throughout their lifetimes, women generally exhibited stronger functional connections among areas linked to higher-order processing compared to men. Interestingly, as men aged, their functional connections in the cerebellum, a region associated with motor control, grew stronger than those of women. Additionally, structural connections in the cerebellum also enhanced more in males than in females with age.
Yumnah Khan, a cognitive neuroscientist at the University of Cambridge, highlighted that the timeline of these sex differences aligns with fluctuations in sex hormone levels throughout life. She suggested that the stronger functional connectivity observed in females—specifically in higher-order processing networks—might be related to mental health, noting that such hyperconnectivity has been linked to depression.
