Amen, a psychiatrist known for his brain-imaging (SPECT) clinical work, argues that psychiatry has relied too heavily on symptom-based diagnosis (matching a checklist to a DSM label) without actually looking at the brain generating those symptoms. His central claim is that conditions like depression, anxiety, ADHD, and addiction are not single, uniform diseases but have multiple distinct brain-based "types," each of which may respond to different interventions — meaning two people with an identical diagnostic label might need very different treatment. The book presents Amen's brain-imaging work and his broader "BRIGHT MINDS" framework, an acronym covering the major risk factors he considers relevant to brain health: blood flow, retirement/aging, inflammation, genetics, head trauma, toxins, mental health history, immunity/infections, neurohormones, diabesity, and sleep. He is critical of psychiatry's traditional reliance on medication as a first and often only response, advocating instead for a broader lifestyle-and-brain-health-first approach — nutrition, exercise, sleep, toxin reduction, and targeted supplementation — alongside conventional treatment where warranted. The tone is confident and sometimes polemical against mainstream psychiatric practice, positioning brain imaging as a missing diagnostic tool.