The objective of this study was to stimate prevalence of sarcopenia and dynapenia in outpatients with Parkinson disease (PD) and to investigate their association with the features of the disease through a cross-sectional design involving 365 participants. Skeletal muscle mass (SMM), as well as strength and gait speed (GS) were assessed by bioimpedence analysis, handgrip dynamometry, and the 4-meter walking test, respectively. Based on these assessments, sarcopenia was diagnosed using the European Working Group on Sarcopenia in Older People criteria. Dynapenia was defined as handgrip strength less than 30 kg in men and less than 20 kg in women. In total, 235 patients (64.6%) had a diagnosis of idiopathic PD. Low SMM index was recorded in 27 patients. Due to gait disturbances and postural instability, GS could not be measured in 98 patients and was found to be reduced in 61.3% of those assessed. Prevalence of sarcopenia and dynapenia was 6.6% (95% confidence interval [CI] 4.3-9.7) and 75.5% (95% CI 70.8-79.9), respectively. Sarcopenia tended to be higher in patients unable to perform GS assessment and was unrelated to the type of parkinsonian syndrome. It was associated with older age, longer disease duration, more severe disease, and higher disability in activities of daily living, as assessed by disease-specific clinical rating scale. Dynapenia was directly associated with parkinsonism other than PD, older age, and disability, whereas regular physical therapy appeared to be a preventive factor. However, it was unrelated to disease duration and severity. Finally, the disability score of activities of daily living was inversely correlated with handgrip strength and GS, whereas no association was found with SMM index.
Being primarily motor disorders, parkinsonian syndromes are characterized by progressive disability in performing activities of daily living. Impaired functional status is a prominent feature of this patient population, independently of disease duration and severity. Sarcopenia is mainly related to advancing disease and, due to a significant sparing of SMM, is an infrequent condition, likely to play a minor role in disability. Several factors could be responsible for this favorable body composition (eg, motor symptoms, levodopa therapy) and deserve further investigation. The prognostic impact of sarcopenia also needs to be addressed.