How can this be reworded safely.
Even after adjusting for the home environment, two of these studies found an environmental influence on language development, pointing to a possible "adoption-related" benefit.
Similar results were observed in a randomized controlled study comparing buprenorphine versus methadone treatment,
including early deficits in temperament, physical development, language, cognitive function, and sensory processing that normalized by the time the patient was three years old.
But at ages three and six, three additional studies revealed persistently poor verbal and language abilities.