They treat dissent, literally, like a mental illness. Sometimes they even end up creating it:
"Xu Lindong’s confinement in a locked mental ward was all the more notable, his brother says, for one extraordinary fact: he was not the least bit deranged. Angered by a dispute over land, he had merely filed a series of complaints against the local government. The government’s response was to draw up an order to commit him to a mental hospital — and then to forge his brother’s name on the signature line.
He was finally released in April, after six and a half years in Zhumadian and a second mental institution. In an interview, he said he had endured 54 electric-shock treatments, was repeatedly roped to his bed and was routinely injected with drugs powerful enough to make him swoon. Fearing he would be left permanently disabled, he said, he attempted suicide three times."