When stress strikes appears to matter as much as how hard it strikes. A study coordinated at the Universidade de São Paulo's Ribeirão Preto School of Medicine, published in Cerebral Cortex, subjected two groups of male mice, adolescents aged 31 to 40 days and adults aged 65 to 74 days, to ten consecutive days of stress and then tracked the electrical behaviour of their medial prefrontal cortex.
In the adolescent brains the damage endured. Excitatory neurons remained persistently hyperactive, inhibitory neurons fired irregularly even after their signal strength normalised, and gamma oscillations, the fast rhythms linked to attention and working memory, were lastingly reduced. Adults got off far more lightly: stress temporarily dampened inhibitory interneuron activity and theta oscillations, but both recovered, and the hyperexcitability seen in younger animals never appeared.
The researchers connect this divergence to psychiatric epidemiology. Around 40 per cent of genes associated with schizophrenia are also linked to depression, and the team advances the hypothesis that trauma in adolescence may relate more closely to schizophrenia risk while adult trauma maps onto depression. The mechanism remains to be confirmed in humans, but the finding sharpens the case for treating adolescent mental health as a critical window in which prevention yields lifelong returns.