Apathy is usually defined as a lack of goal-directed behavior. Although it is observed in about 30% of depressed patients, neurovascular mechanisms underpinning apathy remain little-known.

The main objective of this study was to compare the cerebral perfusion of apathetic depressed patients with non-apathetic depressed patients by arterial spin labeling (ASL), a quantitative and non-invasive perfusion magnetic resonance imaging (MRI) technique. The secondary objectives were to study their clinical profile and their correlation with cerebral perfusion data.

This study was conducted from a cohort of depressed patients in Rennes, France. Eighty-three depressed patients were included, of whom 22 were apathetic (AES≥42), 61 non-apathetic (AES < 42). Everyone got a clinical evaluation with scale screenings, especially for apathy (AES), anxiety (STAI) and anhedonia (SHAPS) as well as a cerebral MRI, including a pseudo-continuous ASL sequence.

Apathetic depressed patients were significantly less anxious and less anhedonic. Apathetic perfused better than non-apathetic in the inferior frontal gyrus (P = 0.022). We found a significant positive relationship between apathy and perfusion of the left frontal inferior gyrus (P = 0.05, r = 0.21). State-anxiety was positively correlated with perfusion of the cingulate cortex, the insula and the left amygdala. Anhedonia was positively correlated with the perfusion of the ventromedial prefrontal cortex, the cingulate cortex and the insula.

We have shown that the clinical and perfusional profiles of apathetic depressed and non-apathetic differ. This study suggests the existence of two distinct neurobiological networks for depressed patients; one involving motivational networks for apathetic patients, and another one involving emotional networks for more anhedonic patients.

The authors have not supplied their declaration of competing interest.