@dijoy Depression is a monster! I’m so sorry both you and your son are having to deal with this. The two times I’ve had to fight this beast were both hormone related; postnatal and the onset of peri menopause.
Men are no different than women…we are all controlled by our hormones. Men can have imbalances too. Low levels of testosterone, thyroid, serotonin and Vitamin B12 can all have significant impact and can be a factor in causing depression.
Has your son been seen by an endocrinologist?
From my personal experience, my physician also studied naturopathy and corrected my hormonal imbalance with a plant based hormone balancing cream. However, it’s not recommended to use these products without discussing with a physician and having hormone levels checked first.

I agree, more mainstream medicine would do well to research the correlation between hormones and depression.
Wishing you peace. Lori.