Abnormal cerebellar volume in somatic vs. non-somatic delusional disorders

Area of Science:

• Neuroscience
• Psychiatry
• Neuroimaging

Background:

• Cerebellar involvement is implicated in schizophrenia's cognitive, affective, and motor deficits.
• Specific cerebellar regions are linked to auditory verbal hallucinations.
• Cerebellar contributions to delusions, and content-specific differences, remain largely unknown.

Purpose of the Study:

• Investigate cerebellar gray matter volume (GMV) differences in patients with somatic-type delusional disorder (S-DD), non-somatic delusional disorder (NS-DD), and schizophrenia (SZ).
• Explore whether cerebellar involvement in delusions varies by content.

Main Methods:

• Structural magnetic resonance imaging (1.0 T) with cerebellum-optimized segmentation.
• Compared GMV in 14 S-DD, 18 NS-DD, 18 SZ patients, and 32 healthy controls (HC).
• Adjusted for age, gender, chlorpromazine equivalents, and illness duration.

Main Results:

• S-DD patients showed decreased GMV in left lobule VIIIa compared to HC.
• S-DD patients exhibited decreased GMV in lobule V and increased GMV in bilateral lobule VIIa/crus II compared to NS-DD.
• Schizophrenia patients showed increased GMV in right lobule VI and VIIa/crus I compared to HC; no significant differences were found between HC and NS-DD.

Conclusions:

• Cerebellar dysfunction is supported in psychotic disorders.
• Distinct cerebellar deficits, potentially related to sensorimotor processing, may characterize delusional disorders with somatic content.