Yes, he had haemochromatosis. It was discovered too late to do anything to reverse the effects, which include depression (suicide is common) and diabetes. Join pain from excess iron build up is also a real doozy.
Plus his health wasn't great.
As a writer, he was spending a lot of time in bars, which he could no longer do, due to health reasons.
He had a pre-disposition to depression.
Impotence, and not being able to enjoy the finer things in life left him feeling very bereft.
In the end all he could do was WRITE about things that made him feel "alive".