Complex sentence: Althusser forcibly lived in various public and private clinics until 1983, when he became a voluntary patient, and stayed, from 1984 to 1986, at an apartment in the north of Paris.
Split into simpler sentences: Althusser forcibly lived in various public and private clinics until 1983, when he became a voluntary patient. After that, he stayed, from 1984 to 1986, at an apartment in the north of Paris.