Cognitive function, psychobehavioral symptoms, and MRI features in patients with non-demented Parkinson's disease, Parkinson's disease with dementia, and dementia with Lewy bodies.

INTRODUCTION

Parkinson's disease without dementia (PD-ND), Parkinson's disease with dementia (PDD), and dementia with Lewy bodies (DLB) are Lewy body disorders characterized by intraneuronal Lewy body pathology. Although the sequence of motor and cognitive symptom onset assists in differentiating PDD from DLB, overlapping clinical features often complicate diagnosis. This study compared cognitive profiles, neuropsychiatric symptoms, and magnetic resonance imaging (MRI) characteristics among PD-ND, PDD, and DLB to identify potential diagnostic markers.

METHODS

A retrospective review was conducted of 213 patients with PD-ND, 85 with PDD, 140 with DLB, and 86 age-matched cognitively normal controls seen between 2011 and 2025. Cognitive performance was assessed using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Neuropsychiatric symptoms and MRI visual rating scales, including ventricular enlargement, global cortical atrophy, medial temporal atrophy, parietal atrophy (Koedam score), white matter hyperintensities, Fazekas scale, Evans Index, and width of the third ventricle, were evaluated.

RESULTS

PDD patients exhibited longer disease duration than those with DLB (P < 0.001). DLB cases demonstrated lower MMSE and MoCA scores and greater neuropsychiatric symptom severity (all P < 0.01). DLB showed more extensive structural brain changes compared to both PD-ND and PDD. A combined imaging model yielded an AUC of 0.768.

CONCLUSION

DLB is associated with more rapid cognitive decline, greater neuropsychiatric burden, and more pronounced atrophy compared to PDD. Combined imaging measures may improve differential diagnosis.