Nationwide, about 44 million Americans meet the criteria for a mental illness last year. At the same time, about 20 million people met the criteria for substance abuse disorder. This means that almost half of people with a diagnosable mental illness are also battling with addiction, and the reality is that both numbers may actually be much higher than reported. There’s even a specific term used by therapists and treatment centers to refer to people who meet the diagnostic criteria for both substance abuse disorder and a mental health problem like depression, anxiety, or PTSD. “Dual diagnosis,” as it’s known, helps practitioners identify and treat both conditions together, since there are so many overlapping factors between addiction and mental health.