Over the last 30 years that I have been doing in-depth interviews with meditators, I have met many who meditate regularly and have become depressed. When I ask them about their practice, they often reveal that they have interpreted the Buddhist or Hindu teachings they are studying in such a way as to detach themselves from their desires, their ego, their loves, and their passion. In other words, they have cut themselves off from everything interesting and thrilling in life.
Depression is a natural result of loss, and if you internalize teachings that poison you against the world, then you will of course become depressed. Detachment techniques were intended only for monks and nuns. Detachment is the DEFINITION of what defines a monk or nun: they take vows of poverty, celibacy and obedience. In other words, they cut themselves off from the desire to make or acquire money, they cut themselves off from their sexual desire, and they cut themselves off from any rebelliousness and independence. This amputation can be a blessing for a soul who really is a monk or a nun, and needs to just go join an ashram. But if you are not a monk or nun, cutting yourself off from life is as depressing as cutting off your foot. It's a loss, and you will suffer grief over the loss.