A recent report in Nature Genetics has revealed more information on the genetic variations that cause the 5 major mental illnesses (link, link). This work builds on previous research published in the Lancet earlier this year. According to these articles, the 5 major mental illnesses are scizophrenia, ADHD, bipolar disorder, depression and autism.I have written before about my depression and this is why I am interested in this research.
Depression sufferers often hear ridiculous statement from believers and non-believers like "cheer up its not that bad", or "why do you need medication for sadness". However, now with mounting evidence that often these mental illnesses can be linked to genetics its no longer a case of demons infesting your body, or "just get over it". People will have to think more carefully about their opinions regarding an illness which can be either passed to children or some random mutation.
Remember, depression is real just like the other major mental illnesses. If you have never had major depression you most likely wont understand what it does to you. It is for this same reason that I will never understand how it is to be colour blind.
Allie at Hyperbole and a Half does a good job at explaining depression.