ADHD is caused by?

• A. Dysregulation of dopamine and norepinephrine.
• B. Loss of dopamine neurons.
• C. Excess serotonin in the cortex.
• D. Autoimmune inflammation of the basal ganglia.

Answer: (A)

ADHD is linked to dysregulation of dopamine and norepinephrine signaling in frontostriatal circuits that govern attention, working memory, and impulse control. This neurochemical imbalance leads to the hallmark symptoms of inattention, hyperactivity, and impulsivity. Stimulant medications increase extracellular dopamine and norepinephrine in the prefrontal cortex, helping to normalize these circuits and improve symptoms. The idea that ADHD results from loss of dopamine neurons describes a neurodegenerative process like Parkinson's disease, which is not typical for ADHD. Excess serotonin in the cortex is not the primary driver of ADHD, and autoimmune inflammation of the basal ganglia is not the established cause either.