Final answer:
Seizures in infants in the 1950s were linked to iodine deficiency, a micronutrient essential for the production of thyroid hormones necessary for brain development.
Step-by-step explanation:
In the 1950s, seizures in infants were commonly linked to a deficiency of the micronutrient iodine . Iodine is crucial for the production of thyroid hormones, which are essential for normal brain growth and development in children. An insufficient amount of iodine during pregnancy can lead to severe consequences, including intellectual disabilities in children due to the hormone's role in brain development. This is why iodine deficiency is considered the most significant cause of preventable intellectual disability in the world.