Gonadal sex hormones, including testosterone and estrogen, are considered crucial in brain development. However, there is little research on the association of HGS in Parkinson disease but in general, HGS is lower in people with Parkinson than in healthy people. HGS is often used as an indicator of measuring muscle strength of the whole body and is considered a practical, fast, easy and independent tool for the observer. This measurement is a reflection of the maximum isometric strength of the muscles of the hand and forearm. A non-invasive and inexpensive method widely used to assess muscle strength is handgrip strength (HGS). Evidence suggests that people with Parkinson have weaknesses in some muscle groups, especially the wrists and elbows even when allowance is made for the slow development of maximal force. Arm muscle function involves manipulating objects that require the use and integration of muscle activity from the shoulder to the fingers.

Dopaminergic deficits in people with Parkinson reduce stimulation in the motor cortex, which can affect the use of motor unit and lead to muscle weakness. Reduction of muscle strength in people with Parkinson has been reported repeatedly. Isometric force control in Parkinson patients is also associated with increased variability in grip force by increasing force magnitude or by removal of visual feedback. In Parkinson patients, there is a delay and disruption in the time and speed of isometric force production in both stages of production and release of productive force. Adjustment of force control is an important parameter for proper hand function which relies on proper activation of the basal ganglia. Coordination of sensory information with movement planning is very important for proper hand movements. In addition, hand function control can be completely compromised. Voluntary movement disorders in Parkinson is specified with a number of specific sensorimotor processing deficits, including general slowness of movement, difficulty in performing sequential movements, reliance on sensory input, especially visual input to guide and correct movement and problems in timing and coordination of movements. This flow of disorders leads to clinical manifestations of the disease, which including movement disorders such as bradykinesia (slow movements), muscle rigidity, resting tremor, and postural instability. Internal nuclei of basal ganglia, deprived of their natural dopaminergic inputs, impair functions leading to abnormal nerve oscillations and synchronization in several basal ganglia-thalamic-cortical circuits. Parkinson is the second chronic neurodegenerative disorder whose main pathophysiology is the destruction of dopamine-containing cells in the basal ganglia. We concluded that HGS was negatively associated with the Parkinson disease, but conversely, 2D:4D may not be a valuable biomarker of elevated risk of Parkinson in elderly males. The regression results showed that the right and left HGS were not able to predict Parkinson disease (P = 0.25, P = 0.16 respectively). Parkinson disease had no significant relationship with 2D:4D of the right hand, left hand, mean finger ratio and D R−L 2D:4D (P > 0.05). The results showed a significant negative relationship between Parkinson disease and the right and left HGS (R = -0.16, P = 0.005 R = -0.17, P = 0.003 respectively). Conversely, HGS for the right and left hands of Parkinson patients were significantly lower than those of healthy males (P = 0.02, P = 0.03 respectively). ResultsĪlthough 2D:4D ratios (right and left hand) of male patients with Parkinson’s disease were higher than those of healthy males, this difference was not statistically significant (P = 0.12, P = 0.40 respectively).

After determining the level of disability of Parkinson patients by a neurologist (level of disability in the range of 1–4), anthropometric indices (height, weight, length of the second and fourth fingers) and maximum HGS were measured. In this study 117 elderly men with Parkinson disease (mean age of 61.66 ± 11.28 years) and 156 healthy control subjects (mean age of 61.86 ± 6.29 years) participated. This study aimed at investigating the relationship between Parkinson’s disease and HGS and 2D:4D ratio. Hand grip strength (HGS) is a suitable measure to evaluate the musculoskeletal system among the elderly and it is considered as an indicator of the overall strength of the body. In addition, decreased muscle strength in people with Parkinson’s has been repeatedly reported. Studies have shown that the second to fourth digit ratio (2D:4D) is affected by the prenatal testosterone and estrogen levels and can predict predisposition to disease. Sex hormones affect the pathogenesis of Parkinson patients and it has been suggested that gender is the most important factor in the development and progression of Parkinson’s disease.

Higher 2d 4d ratio women