Low muscle strength in late adolescence and Parkinson disease later in life.

OBJECTIVE: To evaluate maximal isometric muscle force at 18 years of age in relation to Parkinson disease (PD) later in life. METHODS: The cohort consisted of 1,317,713 men who had their muscle strength measured during conscription (1969-1996). Associations between participants' muscle strength at conscription and PD diagnoses, also in their parents, were examined using multivariate statistical models. RESULTS: After adjustment for confounders, the lowest compared to the highest fifth of handgrip strength (hazard ratio [HR] 1.38, 95% confidence interval [CI] 1.06-1.79), elbow flexion strength (HR 1.34, 95% CI 1.02-1.76), but not knee extension strength (HR 1.24, 95% CI 0.94-1.62) was associated with an increased risk of PD during follow-up. Furthermore, men whose parents were diagnosed with PD had reduced handgrip (fathers: mean difference [MD] -5.7 N [95% CI -7.3 to -4.0]; mothers: MD -5.0 N [95% CI -7.0 to -2.9]) and elbow flexion (fathers: MD -4.3 N [95% CI -5.7 to -2.9]; mothers: MD -3.9 N [95% CI -5.7 to -2.2]) strength, but not knee extension strength (fathers: MD -1.1 N [95% CI -2.9 to 0.8]; mothers: MD -0.7 N [95% CI -3.1 to 1.6]), than those with no such familial history. CONCLUSIONS: Maximal upper extremity voluntary muscle force was reduced in late adolescence in men diagnosed with PD 30 years later. The findings suggest the presence of subclinical motor deficits 3 decades before the clinical onset of PD.

Parkinson's disease: a population-based investigation of life satisfaction and employment.

OBJECTIVE: To investigate relationships between individuals' socioeconomic situations and quality of life in working-aged subjects with Parkinson's disease. METHODS: A population-based cohort comprising 1,432 people with Parkinson's disease and 1,135 matched controls, who responded to a questionnaire. Logistic regression analysis was performed to identify factors associated with life satisfaction and likelihood of employment. RESULTS: In multivariate analyses, Parkinson's disease was associated with an increased risk of dissatisfaction with life (odds ratio (OR) = 5.4, 95% confidence interval (95% CI) = 4.2-7.1) and reduced likelihood of employment (OR = 0.30, 95% CI = 0.25-0.37). Employers' support was associated with greater likelihood of employment (p < 0.001). Twenty-four percent of people with Parkinson's disease for ≥ 10 years remained employed and 6% worked full-time. People with Parkinson's disease also more frequently experienced work demands that exceeded their capacity; this factor and unemployment independently correlated with greater risk of dissatisfaction with life (both p < 0.05). CONCLUSION: People with Parkinson's disease have an increased risk of dissatisfaction with life. Employment situation is important for general life satisfaction among working-aged individuals. People with Parkinson's disease appear to find it difficult to meet the challenge of achieving a balanced employment situation.