Enriched adolescence protected stressed mice from schizophrenia-like changes

The mouse study linked the effect to brain plasticity signals, while patient samples showed lower TrkB levels.

Editorial illustration — not from the study.

In a maternal-separation model of early-life stress, mice developed schizophrenia-like behavioral and cognitive deficits along with oxidative stress, impaired mitochondria, inflammation, cell death and synaptic problems in the hippocampus. Adolescent environmental enrichment reversed these changes and restored signaling involved in brain plasticity.

Experiments with drugs that activated or blocked TrkB supported a causal role for this signaling pathway within the study. The researchers also found that TrkB levels were reduced in neuron-derived exosomes from patients with schizophrenia, although the measure had only moderate diagnostic performance.

What enrichment changed

Maternal separation in mice suppressed CREB-BDNF-TrkB signaling and was accompanied by oxidative stress, mitochondrial dysfunction, neuroinflammation, neuronal apoptosis and synaptic deficits in the hippocampus. Providing environmental enrichment during adolescence prevented the resulting schizophrenia-like behavioral and cognitive deficits and reversed the measured biological abnormalities.

In cell experiments, pharmacologically activating TrkB rescued synaptic deficits caused by oxidative stress. In mice, inhibiting TrkB eliminated the behavioral and cognitive benefits of environmental enrichment. TrkB levels were also significantly lower in neuron-derived exosomes from patients with schizophrenia; the measure had an area under the curve of 0.784, described as moderate diagnostic performance.

Why the findings matter

The findings identify CREB-BDNF-TrkB signaling as a possible link between early-life stress and schizophrenia-related changes in this experimental model. They also suggest that environmental enrichment during adolescence may be a developmentally timed, non-drug intervention worth studying further. The patient-sample result provides translational relevance, but it does not show that environmental enrichment prevents schizophrenia in people.

Evidence and caveats

The main evidence comes from mice exposed to maternal separation, a model of early-life stress, together with cell experiments using pharmacological activation or inhibition of TrkB. These experiments support a causal role for TrkB within the study's framework, but results from this model cannot establish effects in humans. The patient analysis found reduced TrkB in neuron-derived exosomes and moderate diagnostic performance, but the abstract does not provide the sample size or show that the measure predicts future illness or treatment response.

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