Measurement of cerebrum and cerebellum volumes of Parkinson's disease patients with and without tremor dominant and evaluation of the relationship with mild cognitive impairment

Parkinson's Disease (PD) is the second most common neurodegenerative disorder in the population. PD is characterized by both motor and non-motor symptoms. Bradykinesia, rigidity, and resting tremor are cardinal motor symptoms. Cognitive impairment is the most frequently observed non-motor symptom. The objective of this study is to examine the relationship between cerebrum and cerebellum volumes and mild cognitive impairment (MCI) in PD patients classified as tremor-dominant (TD) and postural instability gait disorder (PIGD). The study includes 27 TD-PD, 25 PIGD-PD, and 21 healthy controls (HC). Participants underwent neuropsychological assessments, including the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Verbal Fluency, Digit Span, Clock Drawing, and Luria Sequential Drawing Test. Only those scoring 25 or above on the MMSE were included. Patients were diagnosed with Level 1 MCI and grouped into MCI and Normal Cognition (N). Brain Magnetic Resonance Imaging (MRI) was used to calculate cerebrum and cerebellum volumes with the vol2Brain method. Compared to HC, total, left gyrus rectus, total, right area subcallosa, and posterior cingulate gyrus volumes in PIGD-PD and the left precentral gyrus medial segment volume in TD-PD was significantly larger. TD-PD and PIGD-PD showed significantly increased gyrus supramarginalis volumes compared to HC. PIGD-MCI showed significantly reduced total, right and left cerebellum, total left white matter, and left gray matter cerebellum volumes compared to PIGD-N. Additionally, PIGD-MCI had smaller total,right nucleus accumbens, right globus pallidus, and total, right gyrus frontalis inferior volumes, while TD-MCI had reduced right occipital gyrus volume from PIGD-N. Several levels of correlations were detected among neuropsychological test scores. In conclusion, it is thought that there are volumetric changes in the cerebrum and cerebellum structures of PD patients, depending on whether they have MCI or not, and that impairments in executive functions are specially observed through correlations with neuropsychological tests. Keywords: Dementia, Mild cognitive impairment, Parkinson's disease, Tremor, Volbrain