This retrospective cross-sectional study analyzed 3T MRI scans and clinical data from 65 patients with Parkinson’s disease (PD) at a single center, splitting participants into PD with visual hallucinations (PDVH; n=32) and without (PDnonVH; n=33) using the University of Miami Parkinson’s Disease Hallucination Questionnaire (UM-PDHQ). Groups were comparable on age, sex, cognition, disease severity, medication dose, and intracranial volume. The paracingulate sulcus (PCS) was manually measured in FreeSurfer (Intraclass Correlation Coefficients ≥0.999) and normalized to intracranial volume. PDVH showed significantly shorter right, left, and total PCS lengths than PDnonVH (all p≤.001), with no left–right asymmetry effects. Shorter PCS length correlated with greater hallucination burden (UM-PDHQ; r≈−.39 to −.48). In PDVH, longer PCS correlated with better semantic fluency (r up to .51). In logistic regression, shorter PCS predicted hallucination status (odds ratio per mm=0.98; p=.003; Nagelkerke R²=0.212; 67.7% correct classification).
Findings align with literature linking PCS/medial prefrontal cortex morphology to reality-monitoring and hallucinations (e.g., schizophrenia), suggesting PCS length may reflect a neurobiological predisposition to PD visual hallucinations. PDVH also performed worse on visual immediate and delayed memory, supporting fronto-visual network involvement. The authors propose PCS length as a candidate biomarker and call for larger, multimodal, longitudinal studies to test its prognostic value and mechanistic ties to reality-monitoring circuits.
Reference: Karagoz B, Temel Z, Ertan G, et al. The relationship between paracingulate sulcus length and visual hallucinations in Parkinson’s disease suggests a neurobiological predisposition. Sci Rep. 2025;15(1):23123. doi: 10.1038/s41598-025-04513-3.
