Schizophrenia Genetic Research: Still Running on Empty
By Jay Joseph, Psy.D.
Awais Aftab’s arguments in his 3/21/2020 post “Defending Aggregate Genetic Effects in
Psychiatric Disorders” are
based largely on his claim that the “high genetic heritability of schizophrenia”
and other major psychiatric disorders “has been pretty consistently reported in
[the] literature.” Indeed it has, but the “literature” could still be wrong,
especially when it is based on the acceptance of false assumptions, and on
textbook and other authoritative authors’ frequent failure to critically
analyze (or even read
closely) the original “landmark” studies they cite. Not to mention that, as
a pair of
critics wrote, “The term
‘heritability,’ as it is used today in human behavioral genetics, is one of the
most misleading in the history of science.” (See my description of the
“heritability fallacy” HERE.)
Aftab then asked, in relation to Duncan Double’s
3/20/2020 commentary “The
Causes of Psychiatric Illness,” whether Double can “cite even one good
study which demonstrates that schizophrenia does not have a high genetic
heritability?” A better way of posing this question is to ask whether the body
of research that psychiatry currently cites as showing that schizophrenia has
an important genetic component holds up under critical examination. As I have
attempted to show since the late 1990s, it does not.
Psychiatric genetic arguments that important genetic
factors underlie schizophrenia are based on twin studies that require the
acceptance of obviously false assumptions, and on massively flawed and biased
adoption studies. (Although most psychiatrists claim that “schizophrenia” is a
valid medical disorder which they and others can reliably identify/diagnose,
there is plenty of evidence
that it isn’t. Many critically minded authors now use the term “psychosis.”)
In my 2017
e-book Schizophrenia and Genetics:
The End of an Illusion, I examined in great detail the evidence that
psychiatry puts forward in support of its “high genetic heritability of
schizophrenia” position. I showed that the famous 1960s-1990s Danish-American
schizophrenia adoption studies, performed
by American psychiatric genetic researchers Seymour Kety, David Rosenthal, Paul
Wender and their Danish colleagues, were flawed and biased to an extreme
degree. It is only necessary to carefully read their original publications with
a critical eye to see that these researchers manipulated diagnoses, data, and
group comparisons in order to obtain the desired genetic findings. As Stephen
Jay Gould showed in The Mismeasure of Man, human genetic research has a
long history of investigators “shifting criteria to work through good data
toward desired conclusions,” and creating conditions in which “data” is not
allowed to “overthrow…assumptions.” The Danish-American adoption researchers
continued this scandalous tradition—simply refusing to permit their data to
overthrow psychiatry’s need to establish “schizophrenia” as a valid
genetic/biological medical disorder. The broad term now used to describe this
practice is p-hacking,
which includes various
forms of scientific manipulation, misconduct, or fraud. (For an excellent
description of these practices, see Chris Chambers’ 2017
The Seven Deadly Sins of Psychology.)
Psychiatric twin
studies are based on the utterly false assumption that reared-together MZ
(identical) and DZ (fraternal) twin pairs grow up experiencing similar or
“equal” environments, and it is likely that twin studies of schizophrenia and
psychosis have recorded nothing more than research bias, MZ pairs’ more similar
environments and treatment, MZ pairs’ higher levels of identity
confusion and attachment to each other, and MZ pairs’ greater tendency to
experience “folie à deux” (shared
psychotic disorder) compared with DZ pairs.
Aftab wrote in relation to molecular genetic research that although “there is no evidence of
single genes of large effect sizes for schizophrenia or other major psychiatric
disorders…the evidence…suggests [the existence of] multiple genes of very small
individual effect sizes but a large aggregate effect.” Psychiatric molecular
genetic research dates back to the 1960s. Countless gene discovery claims have
been published since then, especially since the late
1980s, only to be subsequently relegated to the ever-expanding psychiatric
genetics “graveyard”
of false positive results. The most recent claims of “multiple genes of small
effect” are based on associations, not causes, and like previous claims it is extremely
unlikely that they will hold up. Although we have seen many reports that
various genetic variants are “associated” (correlated) with schizophrenia,
decades of molecular genetic studies have failed
to produce variants shown to cause it.
The evidence in favor of environmental causes, coupled
with the lack of evidence in favor of
biological and genetic causes, supports a
psychological/sociological/political/environmental understanding of
“schizophrenia” and psychosis. In support of this position, I highly recommend the book Models of Madness: Psychological, Social,
and Biological Approaches to Psychosis (second ed.), edited by John Read
and Jacqui Dillon. (See also Schizophrenia:
A Scientific Delusion?, second ed., by Mary Boyle.)
Please see the following links to books and articles
where I show that, based on a close examination of the original research
publications, and building on the work of earlier pioneering critics
(referenced therein), there indeed exists a literature “which demonstrates that
schizophrenia does not have a high genetic heritability.”
Schizophrenia
and Genetics
Twin
Studies
The Trouble
with Twin Studies: A Reassessment of Twin Research in the Social and Behavioral
Sciences (2015)
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