The cause of "Clinical Depression" is now being understood as multi-factoral. It is real and needs to be differentiated from the simple label of being "Depressed". Yes, there are (Biological Factors) genetic predispositions to lower production of dopamine levels, underdevelopment of pre-fontal lobe, mis-firing of hippocampus, etc. These same areas can be triggered by trauma to the head (Physical Factors)..
- Even medications, pain killers, etc. can have a profound effect on the release of neurotransmitters. (Environmental Factors)
Let's not forget how most football players interact during practice-- Purposeful striking of the head into pads(Full Force) on top of in-game collisions (2 opposing forces are usually more impactful than direct hits found in boxing) .
When these neuronal pathways are damaged, proven areas of reasoning are never clear for the individual. Example-- Patient w/ early onset of Huntington's disease fail to recognize facial expressions of DISGUST from people. Can you just blame the patient for being naive and say he should know better? My point, he knew that he needed help but could no longer comprehend how? It is very easy to judge that he is a "dirtbag" for leaving his kids, but when you take into account all these factors--his decision was probably the only logical choice he genuinely felt w/ the limitations of his capable thought process. (What he had left) Neurology is a fascinating field and we should not dismiss disorders simply because we do not understand...