Abstract
BACKGROUND: Data from India and other low and middle-income countries reveal high rates of parent-reported shaking of infants. Very high rates of developmental disability have been reported in India. The convergence of these observations provides an opportunity to understand the nature and consequences of a potentially harmful child discipline practice. OBJECTIVE: To study whether caregiver shaking of an infant, even shaking insufficient to lead to an acute medical encounter, is associated with subsequent intellectual disability (ID). METHODS: We conducted a matched case-control study at an academic medical center in Lucknow, India. We compared 75 children with ID of unknown etiology to 75 control children aged 24-72 months, matched by age, gender, maternal age, and maternal education. All children received a neurological evaluation and were IQ and lead tested. We questioned parents about early discipline practices, including shaking. If parents reported shaking, we asked them to demonstrate using a shaken baby simulator. We examined the association between ID and shaking using conditional logistic regression. RESULTS: Children's median age was 43.4 (IQR: 25.1) months; 64% were boys. 24% of all study children were reported shaken before 24 months: 38.% of the case children and 9% of the controls. The adjusted odds of reported shaking of children with ID, before age 24 months, is 8.3 (95% CI: 2.4, 28.2) times higher than controls. CONCLUSION: Shaking children < 2 years of age in northern India is common; a strong association exists between early shaking and unexplained intellectual disability. Possibly contributing to intellectual disability, the role of infant shaking needs to be explored further.