This strikes me as a pretty clumsy article.

> What if mental disorders like anxiety, depression, or post-traumatic stress disorder aren’t mental disorders at all?

Of course they're disorders. That's why they deserve treatment. This bears no connection to the question of whether they're adaptive. Our capacity for physical pain is adaptive, but doctors still treat pain.

> With a thorough review of the evidence, they show good reasons to think of depression or PTSD as responses to adversity rather than chemical imbalances.

Besides clueless commentators on the Internet, who is suggesting depression is simply a matter of 'chemical imbalance'? If that were the case, it wouldn't be brought on by loneliness, and it wouldn't be treated with CBT and talking therapy.