Posted by Randal on August 19, 2002, at 1:21:07
In reply to Re: Genes PLUS environment: Environment?? --Randal » Randal, posted by Ritch on August 18, 2002, at 21:39:42
Mitch,
Sure, we can speculate about all sorts of such factors, but is there really any EVIDENCE for this?
I found a paragraph from a review earlier this year about schizophrenia by Sawa and Snyder in the journal Science that you might find illuminating. (Sawa and Synder, "Schizophrenia: Diverse Approaches to a Complex Disease" Science 296: 692-695 (2002)
"The recent convergence of neuropathologic, neurotransmitter, and genetic studies indicates that we may be coming much closer to
understanding the molecular causes of SZ [schizophrenia]. Although our focus here was on genetic contributions, it is clear that environmental factors also play an important role, as among identical twins the concordance rate for SZ is only 40 to 50%. It had long been thought that the key environmental factors predisposing to SZ are psychological stresses exerted by emotionally distant or manipulative parents, especially mothers. Abundant literature characterized “schizophrenogenic” mothers who place their children in emotional “double binds.” However, familial studies have not supported such notions. Thus, in studies of schizophrenics adopted at birth, the incidence of behavioral disturbance is greater in biologic than in adoptive parents. Studies of identical twins discordant for SZ have identified relevant environmental factors. For instance, the schizophrenic twin is more likely to have suffered birth trauma or experienced a neo-natal viral infection. Interestingly, a recent study of cerebrospinal fluid showed sequences homologous to retroviral pol genes in 29% of recent-onset SZ or schizoaffective patients. These sequences were not detected in subjects with noninflammatory neurological diseases or in normal control subjects."We can (and many have and still do) postulate causes for schizophrenia such as breakdown of the family, stress in modern society, etc. These may sound very plausible, but they just haven't stood up to scientific scrutiny. I would emphasize that schizophrenia is, like bipolar disorder, a heavily genetic disease, again with a concordance rate of 50% for identical twins.
While it may seem like just merely an intellectual exercise to discuss the causes of mental illness, I'll use an extreme (but still very real and common) example to illustrate the importance of not blindly assuming that psychosocial factors are crucial to cause disease. Say someone with schizophrenia or bipolar disorder commits suicide. Traditional theories say that a dysfunctional home environment are responsible for causing the disease in the first place. If the parents of the suicide believe this, it must be a horrible, horrible burden to bear. As indicated by the current understanding of schizophrenia described above, the parents of a schizophrenic child are now "let off the hook".
So is there evidence for bipolar disorder that psychosocial factors CAUSE the disease? Not to my knowledge. Or is it like schizophrenia, a disease where purely genetic factors play an equivalent role? In the absence of any proof is it fair to say that an "environmental" contribution means that the "surroundings" are responsible and suggest the parents can "Raise a child in a steady and stable home, and you reduce the odds that the illness will gain a toehold" as asserted in the Time article? If indeed such statements are not true, this unfairly places an immense burden and a lot of guilt on parents.
As time passes, the severe, lifelong mental illnesses are increasingly found to be caused by genetic and biological factors, especially those affecting the developing brain. Remember how mental illness used to be blamed on evil spirits/demonic possession? Then, with Freud, the focus shifted to psychosocial factors, particularly the early family environment. I think historical beliefs are largely responsible for our current assumption that "psychosocial" factors are the environmental component not accounted for by genes alone.
Sorry to get so preachy, but these issues are of vital importance for how people and their families cope with these horrible, life-threatening diseases. To assign blame, without any evidence, to a less-than-ideal family environment is in my opinion both unnecessary and cruel.
Randal
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> I think I can respond to some questions. I think the stressors and the new fabric of contemporary life (a non-cotton tyranny)contributes to the expression of the illness. After the mid-1930's, more folks lived in an urban instead of a rural environment. To earn a living, you might have to stay up all night working in a local factory. Artificial lights are everywhere, so you can get the stuff you need anytime of the day or nite. Bipolar disorder may be something as simple as an oversensitivity to the natural world's rhythyms expressed around you. It would be sad to die from an artificial chaos.
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> Mitch
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poster:Randal
thread:28868
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