Relation of occupational stress to the age at onset of Huntington's disease

Two hypotheses were tested to determine whether occupational stress was related to the age at onset of Huntington's disease. Using case material drawn from four kindreds in southern Norway, occupations of affected persons were graded into three categories according to their degree of physical stress. Adjusting for the effects of related factors, grade of stress was found to be a significant contributor to the variation in onset age. Minor and severe stress were associated with earlier onset ages than moderate stress; the difference between minor and moderate grades was 9 years. The results are interpreted as conforming to the psychosocial concept of Levi, whereby both under- and overstimulation of sensory functions are more stressful and more potent precipitants of illness than intermediate levels of stimulation.