Parkinson's disease (PD) is the second most common neurodegenerative disease, characterized pathologically by the progressive loss of dopaminergic neurons in the substantia nigra and clinically by the presence of motor symptoms such as bradykinesia, resting tremor, and/or rigidity.Patients with Parkinson's disease (pwPD) often exhibit poor manual dexterity and decreased strength. Fine motor deficits seen in PD include an inability to control cognitive power/force, poor manual dexterity, and motor dysfunction, which includes difficulties achieving the angles, speed, and coordination required for basic movements. Anatomical strength, as detailed in activities of daily living (ADL), is an important indicator of motor characteristics and vitality.Studies have shown a strong relationship between postural control and fine motor functions. For high-quality distal movement, better proximal stabilization is necessary. During upper extremity functions, the body's center of gravity must shift with arm movements, allowing adaptation to changing gravity. Good trunk control is essential in this dynamic process of maintaining balance. Studies examining this link between trunk control, balance, and hand functions are available in the literature. Among these studies conducted in diverse populations, studies involving PD are very few. Investigating parameters such as grip strength, upper extremity dexterity, and reaction time in PD will fill the gap in the literature. Meta-analysis studies have shown that muscle strength and strength in individuals with PD are lower than in healthy individuals. Furthermore, muscle strength in PD has been shown to be related to functional capacity and disease severity. In light of all this information, our study was designed to investigate the relationship between upper body muscle strength, particularly proximal and distal, and manual dexterity in PD. In this direction, the aim of this study is to determine the relationship between proximal and distal muscle strength and upper extremity functional abilities in PD.

Inclusion Criteria:

• Healthy individuals aged 40-75 years, diagnosed with idiopathic PD according to the UK Parkinson's Disease Association Brain Bank criteria by a specialist neurologist, with a Modified Hoehn & Yahr (m-HY) scale stage ≤4, and with a Mini Mental State Examination score of ≥22 for those with training and ≥18 for those without training, and with no known disease, volunteered to participate in the study.
• Individuals with no other known neurological and/or systemic disease
• Individuals without any upper extremity contractures

Exclusion Criteria:

• Individuals with diagnosed and/or treated psychiatric illnesses who are considered unable to complete the tests.
• Those taking neuroleptic medications or antidepressants.
• Individuals with orthopedic conditions that interfere with manual dexterity tests, such as severe dyskinesia, carpal tunnel syndrome, tendon injuries, or finger amputations; rheumatological conditions such as rheumatoid arthritis and osteoarthritis; and individuals with any neurological condition other than PD.

Patients aged between 40 and 75 years (n=40±5) who applied to the Neurology Clinic of the Faculty of Medicine of the University Hospital, diagnosed with Idiopathic Parkinson's disease by a neurologist, having stage ≤4 on the Modified Hoehn&Yahr (m-HY) scale, and having scores of ≥22 in the educated and ≥18 in the uneducated according to the Mini Mental State Examination, and healthy individuals of a similar age group (n=30±5)