# The indirect pathway hypothesis of schizophrenia: insights from perinatal asphyxia

## TL;DR

The paper explores how perinatal asphyxia may increase schizophrenia risk by disrupting brain pathways linked to the disorder.

## Contribution

It proposes a novel mechanistic link between perinatal asphyxia and schizophrenia via dysfunction in the indirect basal ganglia pathway.

## Key findings

- Perinatal asphyxia disrupts neurodevelopmental processes also altered in schizophrenia spectrum disorders.
- PA affects the maturation and balance of basal ganglia circuits, particularly the indirect pathway.
- Indirect pathway dysfunction may lead to thalamic disinhibition and facilitate schizophrenia symptoms.

## Abstract

The comorbidity between perinatal asphyxia (PA) and schizophrenia spectrum disorders (SSD) has been consistently documented in both clinical and experimental research. Individuals exposed to PA show an increased risk of developing long-term neuropsychiatric conditions, including SSD. Experimental models reveal that PA disrupts neurodevelopmental processes also altered in SSD. Moreover, converging evidence indicates that PA can affect the maturation and functional balance of basal ganglia circuits, particularly the indirect pathway, which relies heavily on D2 receptor–mediated signaling and is consistently implicated in the pathophysiology of SSD. Alterations in this pathway may therefore represent a mechanistic link contributing to the shared vulnerability between PA and SSD, where thalamic disinhibition resulting from indirect pathway dysfunction reduces the filtering of information relayed from the thalamus to the cortex, thereby facilitating the emergence of positive symptoms.