Brain connectivity differences between sexes grow from puberty, study finds

Brain connectivity differences grow with age

Sex differences in brain connectivity patterns become more pronounced as people age, according to new research. The study, which analyzed brain scans from over 1,200 people, found these differences increase drastically at puberty and continue to grow throughout adult life.

The preprint was posted on bioRxiv and has not yet undergone peer review. The researchers suggest the work could help explain why men and women have different risks for certain mental health disorders.

How the study was conducted

Researchers from Weill Cornell Medicine analyzed functional magnetic resonance imaging (fMRI) data from 1,286 people aged 8 to 100. The cohort was evenly split between males and females at birth.

The team used an artificial intelligence tool called Krakencoder to identify differences. It analyzed two types of brain connections:

• Structural connections: The physical axonal links between brain regions.
• Functional connections: Synchronized brain activity between different regions.

The analysis was based on sex at birth because data on participants' gender identities was not available.

Key findings on divergence over time

The study found minimal sex differences in brain connectivity in early childhood. A significant divergence begins at puberty.

Functional differences were most notable in higher-order brain networks. These networks, which support attention and decision-making, showed synchronized activity patterns that differed between sexes.

Structural differences in the brain's physical wiring peaked in midlife. They continued to diverge with age, particularly in lower-order networks that process sensory information.

"We are very excited about this study," said lead researcher Amy Kuceyeski. She noted it is the first to compare how these brain network differences evolve across the entire lifespan.

Potential links to mental health risks

The researchers propose these diverging brain patterns could relate to differing mental health outcomes. For example, women are about twice as likely as men to develop anxiety or depression.

Boys are about four times more likely to be diagnosed with autism spectrum disorder than girls. The study suggests understanding these brain connectivity trajectories could offer insights for treatment.

Criticism and the sex versus gender debate

Some neuroscientists caution against interpreting the findings as purely biological. They argue the study does not account for differences in gender roles, which are known to influence brain health and disease.

Daphna Joel, a neuroscientist at Tel Aviv University, stated human brains do not belong in distinct 'female' and 'male' categories. She referred to her 2015 work suggesting each brain is a mosaic of features.

The critics emphasize that sociocultural factors linked to gender are inseparable from biological sex in shaping brain development. They say the study's focus on sex at birth, without gender identity data, limits its conclusions.