Depression dulls sense of smell. If you're depressed, the part of your brain responsible for the sense of smell will be smaller than normal. ... The researchers also measured the volunteers' olfactory bulbs – the part of the brain that gives us our sense of smell – using magnetic resonance ....this time of year I've noticed that my cat's litter box smelled strangely like Christmas...this caused depression of my olfactory senses to the point that I can't smell a thing now! Fucked up!!!!