  Autism Spectrum Disorder (ASD) involves diverse neurodevelopmental syndromes
with significant deficits in communication, motor behaviours, emotional and
social comprehension. Often, individuals with ASD exhibit comorbid conditions,
one of the most prevalent being depression characterized by a persistent change
in mood and diminished interest in previously enjoyable activities. Due to
communicative challenges and lack of appropriate assessments in individuals
with ASD, comorbid depression can often go undiagnosed during routine clinical
examinations, which may aggravate their problems. The current literature on
comorbid depression in adults with ASD is limited. Therefore, understanding the
neural basis of the comorbid psychopathology of depression in ASD is crucial
for identifying objective brain-based markers for its timely and effective
management. Towards this end, using structural MRI and phenotypic data from the
Autism Brain Imaging Data Exchange II (ABIDE II) repository, we specifically
examined the pattern of relationship regional grey matter volume (rGMV) has
with comorbid depression and autism severity within regions of a priori
interest in adults with ASD (n = 44). The severity of comorbid depression
correlated negatively with the rGMV of the right thalamus. Additionally, a
significant interaction was evident between the severity of comorbid depression
and core ASD symptoms towards explaining the rGMV in the left cerebellum crus
II. The whole-brain regional rGMV differences between ASD and typically
developed (TD, n = 39) adults remained inconclusive. The results further the
understanding of the neurobiological underpinnings of comorbid depression in
adults with ASD and are relevant in exploring structural neuroimaging-based
biomarkers in the same cohort.
