Exposure to antibiotics in the first 24 months of life and neurocognitive outcomes at 11 years of age.

“Children who had received antibiotics in the first 6 months of life had significantly lower overall cognitive and verbal comprehension abilities, increased risk of problems with metacognition, executive function, impulsivity, hyperactivity, attention-deficit hyperactivity disorder, anxiety and emotional problems.”

https://www.ncbi.nlm.nih.gov/m/pubmed/31041458/