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Chemical imbalance theoryChemical imbalance is a simplification of the language sometimes used by drug companies [1]in the United Statesin advertisingand consumer literature for psychoactive drugsafter deregulationof pharmaceuticaladvertising. The term has its origins in the 'chemical hypothesis', which refers to a simplification of the series of hypothesised neurochemicalchanges thought to partially underly mental illness. This term is most often used by groups critical of the pharmaceutical treatment of mental illness [2]. Chemical imbalance theory is not a scientific theory, but refers to the lay conception of an idea generated by the use of the term 'chemical imbalance'. Current research in neurosciencedoes indicate roles for changes in the operation of neurotransmittersin the brain, and changes in neuronsand neural structure in the pathophysiology of mental illness, but current models are more complex than simple chemical balances/imbalances. Causality (i.e. whether neurotransmitter changes cause mental illness or whether mental illness affects neurotransmitter levels) is uncertain.
Chemical imbalancesChanges in levels of neurotransmittersand other neurallevel phenomena are hypothesised to be the underlying psychopathologyfor certain mental illnesses, notably clinical depressionand schizophrenia. In 1965, Joseph Schildkraut hypothesized that depression was associated with low levels of norepinephrinein the brain, and later researchers thought serotoninmight be the culprit.[3]] Initially, relatively simple changes in the level of these neurotransmitters were thought to be found in individuals with depression. However, advanced findings began to fine tune the more simple explanations. For example, certain drugsused to treat depression were found to change the levels of neurotransmitters for several days, but then return to normal, well before any effect was observed on the depressive episode. Such findings implicate more complex mechanisms, such as changes in neurotransmitter production, transmission, re-uptake, and [[neuron|neural] sensitivity. In addition to depression, changes in levels of neurotransmitters have also been implicated in anxietydisorders, bipolar disorder(manic depressive disorder), schizophrenia, and Parkinson's disease. As well as changes in serotoninand norepinephrine, dopaminesystems have also been considered. So, while all biology is essentially chemical in nature, rather than being caused by simple chemical imbalances, mental illness is now widely recognized to be caused by complex and, in many cases, as-yet unknown factors. According to Jaelline Jaffe and Jeanne Segal, "The misconception the [drug] commercials foster is that the brain somehow develops a chemical imbalance and the result is depression, occurring in a single directional process. In fact, the relationship between brain chemistry and experience is a two-directional phenomenon: Life experience affects brain chemistry at least as much as brain chemistry affects life experience. The 'chemical imbalance' hypothesis is not wrong. It's just not entirely correct." Use of drugs to correctPsychiatric drugsinfluence levels of neurotransmitters in the brain, and perhaps underlie the genesis of the term 'chemical imbalance theory'. Most people believe that the psychiatric drugs, such as antidepressants, 'correct,' or move towards average levels, the levels of neurotransmitters in the brain. However, rather than restoring 'normal' levels, these drugs frequently attempt to compensate for changes in sensitivity to or production of neurotransmitters, usually in a relatively isolated part of the brain (despite the drug changing more global levels of the neurotransmitters). Limitations on the use of medicationsMost disorders treated with medication have a hypothesised neurochemical mechanism, but it is important to note that chemical imbalances are not believed to explain all psychiatric differences, nor are medications used to treat all neurological or psychiatric issues. Some mental illness, such as some patients with 'pure' Borderline Personality Disorder, may not have a significant biochemical basis underlying it; these patients will typically not find that their symptoms are usefully treated with drugs. Similarly, when significant neuroanatomical differences are involved, the effectiveness of drugs is limited. For example, autismresearchers have found differences in gray and white matter volumes, neuron size, brain mass, and locus of brain function; differences which may be accounted by unknown factors, perhaps involving the interaction of 15 to 100 different genes. ControversyCritics contend that psychiatric drugs, intended to alter neurochemicalprocesses by manipulating neurotransmitter levels, are not always efficacious, not always safe, and not necessarily a scientifically sound method for improving mental health. The number of different chemicals in the brain and their unknown interactions limit understanding and increase the likelihood of unforeseen complications. Moreover, critics assert, the psychiatric establishment merely assumes patients who are diagnosed with a given mental illness always have a chemical imbalance in their brains, even though behavioral checklists, and not actual chemical measurements, are used to reach a diagnosis. Psychiatric diagnostic practices in the United Stateshave come under criticism for over-reliance upon these behavioral checklists rather than thorough, whole-body medical testing. For example, in a Floridapsychiatric hospitalstudy from the 1980s, one hundred patients diagnosed with a mental illness were subsequently given a complete medical exam, after which it was discovered nearly half of the patients? psychiatric problems were secondary manifestations of an undiagnosed medical problem, such as hypothyroidismmimicking depression.[4] Most, if not all, hospitals in the United States currently require a medical exam be done on all patients admitted to an inpatient psychiatric unit. The author of the study, psychiatrist Mark Gold, remains a strong advocate that addiction and psychiatric disorders are rooted in complex chemical imbalances and that effective treatment is available for most correctly diagnosed psychiatric patients from various drug treatments -- an opinion that he shares with the majority of the medical community. Even when neurological and neurochemical differences are associated with certain behaviors, the practice of pathologizing these behaviours has been questioned by some activists and people who have been diagnosed with mental illnesses. Because neural mechanisms imply a physiological difference underlying mental illnesses, they appear to justify the use of medication in treatment. Critics argue that the legitimacy given to medication by neural mechanisms can lead to an over-reliance on medication. Similarly, the perceived efficacy of medication as a treatment implies an underlying neural mechanism. Critics also allege that pharmaceutical companies have a conflict of interestwhen they fund research into biochemical mechanisms behind mental illness and the efficacy of medication at reducing behavior differences. Further controversy is engendered by the links between some critics of psychiatry and the Church of Scientology. While Anti-psychiatryis not equivalent to Scientology, Scientologymaintains several organizations like the Citizens Commission on Human Rightswhich have been outspoken critics of the biological basis of mental illness, sponsoring websites critical of "chemical imbalance" [5][6]. Here also, there may exist a substantial conflict of interest as Scientologyadvocates and sells an alternative and expensive non-pharmacological treatment known as Dianetics. Popular culture and advertisingThe chemical imbalance theory, according to critics, is routinely presented as ?fact? so often it has become widely accepted as fact, despite having been challenged repeatedly. The Pfizerdrug company has heavily promoted its antidepressant drug, Zoloft. The ads assert mental illness may be due to a chemical imbalance in the brain, and that "Zoloft works to correct this imbalance." Without mentioning its own name, Eli Lillyurges viewers to seek treatment for depression, and to visit their website, DepressionHurts.com, because "Many researchers believe depression is caused by an imbalance of naturally occurring chemicals, serotonin and norepinephrine, in the brain and the body." Diagnostic utilityThere are advanced imaging techniques such as Positron Emission Tomography (PET Scans) that can test for chemical imbalances. Changes in levels of neurotransmittermetabolitesare detectable in urineand cerebrospinal fluidand have been associated with certain mental illnesses, but are not sufficiently predictive for successful diagnosis. Thus, Psychiatricdiagnosesare usually made based on algorithmic(DSM-IV) criteria outlined in diagnosticmanuals, primarily through reference to the Diagnostic and Statistical Manual of Mental Disorders(DSM). In practice, psychiatric diagnoses rely upon a physician's judgments about a patient's medical history, clinical evaluation of symptoms, and from patient response to psychiatric drugs. Pharmaceutical company literature continues to explain the operation of psychoactive drugsin terms of chemical imbalances, and restoring a chemical balance closer to 'normal'. The research underlying the mechanism by which the drugs are thought to work is typically justified by clinical trialsdemonstrating their efficacy. Cautionary measuresAn important consideration with regard to chemical intervention is the potential for relapsing into depressionor other psychiatric conditions when medication is discontinued abruptly or without medical supervision. Aside from malnutrition, the only certain means of creating chemical imbalances in the brain is the use of psychotropicchemicals, a category which includes both legal prescription drugs and illegal drugs like LSDor cocaine. Side effects from psychotropic drugs can be significant. Great care must be taken to prevent severe withdrawalsymptoms after using psychotropic drugs. Neuroleptic drugs (typically used in the treatment of schizophrenia) are particularly dangerous to withdraw from quickly. Rebound psychosis is common and can leave a patient more unstable than they were prior to taking the neuroleptic in the first place. See alsoCurrent neuroscience perspectives
Critical perspectives
External linksFDA request for comments
Current neuroscience theories
Critical views
Proponent views
Categories: Anti-psychiatry| Psychiatry| Theories
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