What data do exist is not encouraging. The medications used to treat ADHD have important side effects and require medical monitoring. Autism is a brain disorder. Mental health refers to the successful performance of mental function, resulting in productive activities, fulfilling relationships with other people, and the ability to adapt to change and to cope with adversity. What it means to be mentally healthy is subject to many different interpretations that are rooted in value judgements that may vary across cultures.
Mental illness refers collectively to all diagnosable mental disorders.
At any given moment, a person's mental status reflects the sum total of that individual's genetic inheritance and life experiences.