I've had a lot of interactions with various people over mental health issues lately, and I keep coming across this idea that the majority of these problems are 'chemical'.
I do accept that some mental health issues are caused by biological factors - my DH has low testosterone which affects his ability to manage anxiety.
But I do feel that people (esp in the UK) are very quick to identify the cause of any MH Issue as 'chemical' rather than to attribute it to a reaction to something in their past or present life...