A prospective study of cognitive impairment in Parkinson’s disease: clinical, neuropsychological, and neuroimaging correlates

Aim: Parkinson’s disease (PD) is a progressive neurodegenerative disorder marked by dopaminergic neuron loss, leading to motor and non-motor symptoms. Cognitive impairment in PD (PD-CI), ranging from mild cognitive deficits to dementia, significantly reduces quality of life and increases caregiver burden. This study aims to identify predictors of PD-CI, potentially supporting early interventions. Methods: This one-year prospective observational study included 80 idiopathic PD patients recruited from Al-Azhar University Hospitals. Inclusion followed the Movement Disorder Society (MDS) Clinical Diagnostic Criteria for PD, with evaluations conducted at baseline, 3, 6, and 12 months. Patients underwent clinical assessments [Unified Parkinson’s Disease Rating Scale, Part III (UPDRS-III), Hoehn and Yahr (H-Y), Beck Depression Inventory (BDI), and Hamilton Anxiety Rating Scale (HAM-A)], cognitive evaluations [Brief International Cognitive Assessment for MS (BICAMS) and Montreal Cognitive Assessment (MoCA)], magnetic resonance imaging (MRI), and laboratory testing. Exclusion criteria included conditions such as cerebellar abnormalities, early dementia diagnoses, and other Parkinsonism causes. Results: Cognitive impairment was observed in 41.25% of patients. Those with cognitive impairment were older, had a longer disease duration, and exhibited higher fasting blood glucose (FBS) levels and lower thyroid-stimulating hormone (TSH) levels compared to patients without cognitive impairment (p < 0.05). Brain atrophy was detected in 4 (5%) patients in a subset of patients with PD, which was particularly pronounced in regions associated with cognitive function, such as the hippocampus and frontal lobe. Higher H-Y, UPDRS-III, and BDI scores correlated with cognitive decline, while lower MoCA and Symbol Digit Modalities Test (SDMT) scores predicted impairment (p < 0.05). Conclusions: Cognitive impairment in PD is associated with advanced age, longer disease duration, metabolic factors, and structural brain changes. These findings suggest the potential for a predictive model to identify early cognitive decline in PD, enabling timely intervention and improved patient outcomes.