For years, scientists have known that regular physical activity can help lower the risk of dementia. But new USC research suggests that it’s not only the amount but also the activity’s context — for work or for leisure — that makes a difference.

A meta-analysis of more than 4.2 million people has found that leisure-time exercise — activities such as walking, cycling, running, swimming or playing sports — is associated with a substantially lower risk of dementia. In contrast, physical activity performed as part of a job appears to be linked with a higher risk of developing the condition.

The findings, published in The Lancet Public Health, are the first to systematically examine whether the so-called “physical activity paradox” extends to dementia. This paradox, well documented in cardiovascular research, describes the surprising observation that physically demanding jobs do not provide the same health benefits as voluntary exercise — and may even increase disease risk.

Healthy sleep patterns in mid life are linked to longer working life expectancy, suggest the findings of a large study of working age men and women, published online in Occupational & Environmental Medicine.

School-based mental health programs face a persistent problem: the students who need help most often benefit least. A new UCLA study found the reverse. Among teenage girls in a program combining structured breathing techniques with social-emotional learning, those who had experienced the highest levels of childhood trauma showed the largest gains in social connectedness, according to findings published in the Journal of Research on Adolescence.

Fluctuations in estrogen influence the brain, helping reshape connections between neurons. In a new study, University of Delaware researchers showed that a specialized imaging technique called magnetic resonance elastography (MRE) can detect estrogen-dependent mechanical changes in the hippocampus, a brain region involved in memory and learning, across the reproductive cycle.