Objective: To investigate associations between minor hallucinations (MH), cognition, CSF biomarkers, and neuroimaging findings in non-demented patients with idiopathic Parkinson’s disease (PD).
Background: MH including presence or passage hallucinations and illusions, frequently occur in PD. They can emerge early and are considered potential markers for future cognitive decline. Their relationship to Alzheimer’s disease (AD) co-pathology and structural brain changes remains unclear.
Method: Non-demented PD patients (n=36) were included. CSF Aβ1-42, phosphorylated tau181, total tau, neurofilament light chain (NfL) were analyzed. Structural MRI was obtained in 26 patients, and 23 underwent detailed neuropsychological assessment. Voxel-based morphometry (VBM) was performed and gray matter (GM) density was compared between PD with (MH-PD) and without (nonMH-PD) minor hallucinations. Whole-brain and brainstem analyses were conducted. Associations with CSF biomarkers and cognition were explored.
Results: MH were present in 55% of the patients: 38% had presence hallucinations (PrH), 38% passage hallucinations (PaH), 25% illusions. No significant differences were found in age at motor symtom onset, disease duration, LEDD, sex, or education, though the MH-PD group was younger (p=0.06). CSF biomarker levels did not differ significantly. MH-PD patients performed worse in Benton Judgment of Line Orientation (p=0.027), Stroop Response Count (p=0.006), Stroop Time Difference (STD) (p=0.007). STD correlated positively with CSF NfL (B=0.0504, p=0.0311, R²=0.365). VBM revealed no differences between the PrH and illusion subgroups. However, patients with PaH showed greater GM density in two clusters compared to non-PaH: left fusiform/parahippocampal gyrus (p-fwe<0.002), right middle temporal pole/fusiform gyrus (p-fwe=0.015). No significant correlations were found between these clusters and CSF biomarkers. Brainstem nuclei and DMN, DAN, and VAN did not differ between groups.
Conclusion: In this study, MHs were found to be associated with executive and visuospatial dysfunctions, as well as structural changes in visual-limbic regions. Increased GM density in patients with PaH may reflect compensatory processes or early network alterations preceding atrophy in non-demented stage. The association of CSF NfL with Stroop supports the potential of MHs as early clinical and biological markers of cognitive vulnerability in PD, independent of AD co-pathology.
To cite this abstract in AMA style:
E. Hacılar, B. Samancı, U. Ay, S. Yörük, E. şahin, M. Alaylıoğlu, E. Kurt, E. Dursun, H. Gürvit, B. Bilgiç, D. Gezen-Ak, T. Demiralp, H. Hanağası. Neuroimaging and CSF Correlates of Minor Hallucinations in Parkinson’s Disease [abstract]. Mov Disord. 2025; 40 (suppl 1). https://www.mdsabstracts.org/abstract/neuroimaging-and-csf-correlates-of-minor-hallucinations-in-parkinsons-disease/. Accessed October 5, 2025.« Back to 2025 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/neuroimaging-and-csf-correlates-of-minor-hallucinations-in-parkinsons-disease/