I took a Depression tests a few years back, which included kind of an IQ test-ish stuffs. Depression supposedly can lower brain function and make you dumber.
The doctor was like "Your results were superb, not the best I've seen in my life but still great." And then still said I had Depression.
So here's the thing, why does Depression make you dumber? Because if you have Depression, it means you fell for doctors labelling you as Depression just so that they can give you random pills and make money.
I fell for it, so that makes me one step dumber than I used to be.