Depression and anger are like cousins that like to play together. Men in particular seem to show clinical depression by a marked increase in irritability, anger, or rage. Does depression cause anger or does anger cause depression?
Here is how I see the relationship between depression and anger. Clinical depression lowers our stress tolerance. Things that normally would not bother us become extremely bothersome or annoying. So it is really the increased stress that causes the anger, but the increased stress is caused by the depression.
We can illustrate the dance of stress, depression and anger by considering the tires of a car. Properly inflated tires can resist the stress of paved roads with their common irregularities. But depressed, deflated tires force everything to slow down and this makes the trip longer and more stressful. The kids in the back seat are more likely to be angry. The tires did not cause the anger, but they changed the stress-coping balance.