Friday, May 21, 2010

Rethinking Mental Disorders

An article posted May 20th on

By Kristina Chew

Psychiatric or mental disorders such as schizophrenia, bipolar disorder, depression and psychosis are better understood and treated as 'disorders of the brain' according to an article by Tom Insel, M.D., Director of the National Institute of Mental Health, and Philip Wang, M.D., Deputy Director of NIMH. The article, Rethinking Mental Illness, is published in the May 19th issue of the Journal of the American Medical Association. The authors note that, while there have been many 'insights gained from genetics and neuroscience'---such as twin studies that show high heritability for autism, schizophrenia, and bipolar disorder---such research explains only a 'fraction of the heritability' of mental disorders. (For instance, some182 genes have been identified as linked to eating disorders, and some 100 to autism.) These should rather be seen as 'disorders of brain circuits':

"The genetics of mental illness may really be the genetics of brain development, with different out comes possible, depending on the biological and environmental context."

Other advances in the field of genetics contribute to a reconceptualization of mental disorders. Epigenetics looks at the inherited changes in gene expression caused that are caused by something other than than changes in the underlying DNA sequence; Insel and Wang note that:

"The same twin studies that point to high heritability also demonstrate the limits of genetics: environmental factors must be important for mental disorders......The advent of epigenomics [the study of the factors that control genes], which can detect the molecular effects of experience, may provide a powerful approach for understanding the critical effects of early-life events and environment on adult patterns of behavior."

Further, the authors write that the behavioral and cognitive symptoms that indicate 'mental illness' may actually be the 'late stages' of neurological processes that, if detected at early stages, might be better and more fully treated:

"As a result, interventions, rather than being ameliorative or rehabilitative, could become preemptive or even preventive. But this transformation in diagnosis and treatment, which can be informed by recent progress in cardiovascular disease and cancer, will depend on an intense focus on the genetics and circuitry underlying mental illness to ensure new approaches to detecting risk, validating diagnosis, and developing novel interventions that may be based on alter ing plasticity or retuning circuitry rather than neurotransmitter pharmacology."

As an example, in the past several years, autism has gone from being seen as a psychiatric, and even psychogenic, disorder, to a neurological/neurodevelopmental one, with significant consequences in how autism is conceived of, treated and, too, perceived by the public. Autism was once thought to be caused by bad parenting, by 'refrigerator mothers' who were emotionally withdrawn and 'cold,' and therefore did not 'bond' with their children, who 'withdrew into autism'; the damage wrought to families and individuals by these misconceptions is unmeasurable. Seeing autism as a neurodevelopmental disorder---due, perhaps, to 'abnormalities' in synapses in the brain does change how autistic individuals are see by others.

Similarly, understanding that an eating disorder such as anorexia nervosa is biologically based rather than simply putting the blame on parents, on our society's and culture's equating being thin with success, has significant changes on treatment and, again, understanding, and this can make a huge difference in people's (parents, for sure) lives. Societal factors do play a role, but seeing anorexia as biologically based---a recent study of brain imaging has found neurocircuit dysregulation in anorexics---can have real changes for people's lives and, hopefully, for the ultimate outcomes of those diagnosed with these conditions.

Also see:

NIMH Builds New Framework for Understanding Mental Illness

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