This may be true for depression and bipolarity, but there's certainly room
for doubt in the case (cases) of schizophrenia. I just read (more
recently than the Golden Bough, which was about a month and a half ago) a
book by Laing and Esterson called _Sanity, Madness, and the Family_ (or
maybe the other way around), which presents, through eleven case
histories, the premise that the behaviours and thought patterns ordinarily
considered 'symptoms of the illness of schizophrenia' are actually
comprehensible responses to a mentally untenable social environment.
Contributing to this environment are several behaviours on the parts of
the parents of the schizophrenics in the book, including:
1.) denial of the individual's own statements about eir own thoughts,
perceptions, and experiences.
2.) constantly sending contradictory messages, and denying the existence
of the contradiction.
3.) refusal to tolerate any act that constitutes differentiation from the
parent at adolescence, and/or perception of even the smallest of such acts
as 'sick' or 'evil'.
In my abnormal psych class in college, we were taught the
'diathesis-stress model' of schizophrenia, in which the individual is
believed to have a genetic/chemical predisposition toward schizophrenia,
which is then bought out by stresses at adolescence, in some cases.
This all makes sense to me, particularly knowing my grandmother, who raised
one schizophrenic and three apparently mentally healthy
children.
Some cases of schizophrenia respond to medication; others don't. Your
mileage on the word 'respond' may also vary. My uncle, in any case, is
often raving nuts.
Eva