system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If ADHD is caused by having a lower baseline dopamine level, why is it so hard to diagnose? Can't we just measure dopamine levels?
gpt
The causes of most mental health problems are poorly understood and the involvement of neurotransmitters like dopamine and serotonin is inferred only by indirect evidence. Plus they have different roles in different parts of the body, and even in different areas of the brain. So far, attempts to develop lab measures to help with diagnosis and treatment have mostly failed.