23% of U.s. Adults Live with a Mental Illness (2022)

> The NSDUH AMI and SMI estimates were generated from a prediction model created from clinical interview data collected on a subset of adult NSDUH respondents (4,912 total respondents between 2008 and 2012) who completed an adapted (past 12 month) version of the Structured Clinical Interview for DSM-IV-TR Axis I Disorders (Research Version, Non-patient Edition) (SCID-I/NP; First, Spitzer, Gibbon, & Williams, 2002), and was differentiated by level of functional impairment based on the Global Assessment of Functioning Scale (GAF; Endicott, Spitzer, Fleiss, & Cohen, 1976).

Diagnostic criteria are imperfect. You can put the same person in front of various doctors and get differing diagnoses. On the whole though, experts tend to agree more than they disagree. Someone has to self-report symptoms that place them a couple of standard deviations away from the mean, and for many disorders like ADHD (combined type here!), you need someone who has known you for a long time like a parent or spouse that can speak to your behavior over a long span of time.

As someone who really struggled to get a diagnosis as an adult, followed by medication, I would suggest trying to get a diagnosis from a psychiatrist. Go through the process and expense and let us know how easy it is. It was a nightmare for me despite having good insurance. A doctor's note for a mental health day is very different from getting diagnosed with a developmental or personality disorder.

Lastly, while people can and often do blame their disorders for unwanted behavior, we still have agency. Most disorders are manageable with treatment, and it's possible to "cure" in certain cases. Children medicated for ADHD will most likely not need medication for it as adults. Having a disorder isn't an excuse or shield for bad behavior. In many cases you can't address the bad behavior at the root level without knowing. For my case it helped me stop being so anxious I was giving myself ulcers because I had the words to describe what was going on, and a treatment plan that I saw was giving me results. I still struggle with certain symptoms, but it is my responsibility to work through those gaps, and medication+therapy have made it possible to put in that work.

For whatever it's worth when I went to university a decade ago for my undergrad in neuroscience the figure cited was "50% of Americans will meet clinical thresholds for something in the DSM-V at least once in their life". This isn't very surprising in that light. A lot of people exist at sub-clinical thresholds.