https://www.statnews.com/2017/09/06/donald-trump-mental-illness-diagnosis/

I helped write the manual for diagnosing mental illness. Donald Trump doesn’t meet the criteria

My long experience with psychiatric diagnosis has taught me a recurring and painful lesson: Anything that can be misused in the DSM will be misused, especially when there is an external, nonclinical reward for doing so. We decided to include narcissistic personality disorder in the DSM-III 40 years ago purely for clinical reasons. We never imagined it would be used as ammunition in today’s political warfare.

To qualify for narcissistic personality disorder, an individual’s selfish, unempathetic preening must be accompanied by significant distress or impairment. Trump certainly causes severe distress and impairment in others, but his narcissism doesn’t seem to affect him that way.

Buried in the noisy debate about Trump’s mental health is the misinformed and noxious assumption that mental illness somehow automatically disqualifies someone for high leadership position. If this were policy, Abraham Lincoln and Winston Churchill both would have been lost to history due to their battles with depression.