In considering the cause of depression, it is important to rule out a number of medical conditions first. Particularly in this age of Dr Google, patients may feel depressed and then look to herbs or natural therapies for depression and then go ahead treat themselves, not realising they may have a physical explanation for feeling depressed. This list includes hypothyroidism, coeliac disease, iron deficiency, poorly controlled diabetes and even post-viral conditions.

I was reminded of this during the last flu season, when for three or four weeks after the symptoms of fever, cough, achy joints and congested head had resolved I still felt lethargic, sleeping long hours, no motivation and feeling down. I was aware that this was purely a physical response to the illness, and just rode it out. It made me more sympathetic to those who suffer post-viral fatigue following Ross River Fever, Barmah Forest Fever, Glandular Fever and many other viral infections that can leave people feeling depleted and depressed for a long time.

In fact, I often see patients with Chronic Fatigue Syndrome who have been prescribed antidepressants. In situations like this the line blurs between the illness causing the depression and the depression developing as a response to how the person feels about having a chronic debilitating illness.