No suicide note was found, but the 37-year-old man had posted on social media before the incident that he was struggling mentally and was very worried about not being able to take care of his family. A source said he had suffered from depression.

Police psychologist Michael Fung Ho-kin explained that emotional illnesses could not be “cured” by a hike or a meal after which the sufferer could “go home and become happy again”.

The Post looks at the prevalence of depression in the city and the different treatment strategies.

1. What is depression?

Depression is a common mood disorder affecting 5 per cent of men and 10 per cent of women in developed countries. It is characterised by symptoms such as a persistently depressed mood, loss of interest and energy, and negative thoughts.