I vaguely remember that Soviet Union had a tendency of sending some political opponents in psychiatric wards to be treated as mentally ill. Does anyone know if

I vaguely remember that Soviet Union had a tendency of sending some political opponents in psychiatric wards to be treated as mentally ill. Does anyone know if there have been studies or reports that indicate whether this sort of technique works in the long run? In addition to it being inhumane, I can see it going two completely different ways: either getting rid of political opponents/Muslims/... or fostering revolution/martyrdom.