Does Adult ADHD Always Begin in Childhood?
The answer is yes — always. Although the disorder is called adult ADHD when it affects adults, the adult version is actually an extension of childhood ADHD. There is no ADHD that begins in adulthood or that only affects adults.
However, this is not to suggest that the childhood and adult versions of ADHD are identical. ADHD is a neurobiological disorder that changes as you age, so the symptoms you experienced as a child are likely to be much different than those you experience as an adult.
In general, symptoms of hyperactivity decrease as you get older and symptoms of inattention, impulsivity, and problems with executive functions (planning, organizing, and prioritizing) tend to increase.
ADHD symptoms also manifest themselves in different ways as you age. Your symptoms of impulsiveness at ages seven and at age 15 may bear little resemblance to the symptoms of impulsiveness as a 42-year-old.
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Researchers believe that future studies on the developing brains of infants and young children may yield important clues as to what causes the onset of ADHD and why some brains never reach full maturity.
Do All Children Have ADHD as Adults?
The answer is no. According to research conducted by the NIH, 50 percent of children with ADHD grow out of the disorder in their twenties. This is because certain brain regions in children with ADHD tend to mature later than normal.
The research used MRIs to compare the brains of 400 children with and without ADHD. The middle portion of the brain, responsible for controlling action and attention, matured later than normal in children with ADHD.
The study concluded that many children with ADHD eventually catch up with children without the disorder and experience a decrease in symptoms such as hyperactivity and inattention as they mature.

