The association between switching hand preference and the declining prevalence of left-handedness with age

Objectives. This study determined the prevalence of left-handedness and of switching hand preference among innately left-handed subjects. Methods. Subjects of Swiss nationality (n = 1692), participating in a popul ation-based survey in Geneva, Switzerland completed a questionnaire on inna te hand preference and current hand preference fur writing. Results. From 35 to 44 years of age to 65 to 74 years of age, the prevalenc e of innate left-handedness declined from 11.9% to 6.2% (trend P = .007). I n these same age groups, the proportion of innately left-handed subjects wh o switched to the right hand for writing increased from 26.6% to 88.9% (tre nd P = .0001). Conclusions. Across generations, we found an increase in the prevalence of switching hand preference among innately left-handed subjects. This phenome non could be explained by social and parental pressure to use the right han d.