Structural Habenula Differences and Avoidance Behaviour in Parkinson's Disease

The habenula is an important node in the brain for the processing of aversive stimuli and motivated behaviour and has been identified as a site of potential importance in Parkinson's Disease (PD). Here, we quantify bilateral habenula volume in PD patients and matched controls, showing that this structure is enlarged in PD. Across the whole sample, larger habenula volume is specifically associated with greater avoidance behaviour. Control analyses confirm that this effect is specific to avoidance behaviour, not only present in the PD group, and unaffected by PD medication status. Our findings add to a growing body of literature reporting structural differences in the habenula between patient groups and controls. By linking habenula volume to behaviour, we contribute to understanding the habenula's function and broader relevance to PD and related pathologies.