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Biological psychiatry

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Biological psychiatry, or biopsychiatry, is an interdisciplinary science which is concerned with studies of the biological bases of behavior - biochemical, genetic, physiological, and neurological - and the application of knowledge derived from these studies in the treatment of mental illness.[1][2][3][4]

The term has been used in modern peer-reviewed medical literature since 1953[5]. However, certain elements of what is today called biological psychiatry extend back to ancient times.

While there is some overlap between biological psychiatry and neurology, in general neurology focuses on disorders of the nervous system such as epilepsy, cerebral palsy, encephalitis, neuritis, Parkinson's disease and multiple sclerosis, among others. By contrast, biological psychiatry at the research level seeks to understand the biological basis for behavior. At the clinical level, it is concerned with how to apply theoretical knowledge in the treatment of mental health disorders.

Biological psychiatry promises to revolutionize understanding and treatment of mental health disorders. However, a central theory of biological psychiatry (monoamine hypothesis, popularly known as the "chemical imbalance theory") is deeply flawed in its original form.[6] The history of the field also includes treatments that are brutal to modern sensibilities.[7]

Scope and detailed definition

There are many naturally-occurring and artificially-induced biological influences on mood and behavior:

Biological psychiatry seeks to understand the neurobiological basis of these factors and how they relate to behavior and mental illness.

Biological psychiatry is a broader field than commonly-mentioned disorders (e.g, depression, schizophrenia) and associated drug treatments. On a research level, it includes all possible biological bases of behavior - biochemical, genetic, physiological, neurological and anatomical. On a clinical level, it includes various therapies, including but not limited to drugs, diet, avoidance of environmental contaminants, exercise, and life stress[13], all of which can cause measurable biochemical changes.[14] The biological psychiatrist views all of these as possible etiologies of or remedies for mental health disorders.

However, the biological psychiatrist typically does not discount psychoanalytic approaches (talk therapies). Medical psychiatric training generally includes both psychodynamic and biological approaches.[15] Accordingly, psychiatrists are usually comfortable with a dual approach: "psychotherapeutic methods...are as indispensable as psychopharmacotherapy in a modern psychiatric clinic"[16], "most of mental diseases require a synthesis of both biological and psychological procedures" (Krull, 1990).

There is a common perception of biological psychiatry as a relatively recent trend, but this may be incorrect: "Little support was found for the suggestion that major shifts have occurred in the explanatory paradigms used by psychiatry over the century. Modern interest in biological psychiatry is therefore not a new departure, but appears rather as the continuation of a long-standing inclination."[17]

Early history

Biological psychiatry is not a new movement. Hippocrates (46O-377 BC) declared insanity to be a biological disturbance and used approximately 250 drugs to treat this. [18] In ancient China acupuncture was used to treat depression.[citation needed]

During the Renaissance period, dietary measures were used to treat depression. Lithium salts were used as prophylactic treatment against depression in the early 1900s.[19]

Primitive, harmful early techniques

From ancient times some biological approaches to mental health disorders have been harmful. These included trepanation (boring holes in the skull), water shock, bloodletting, and transfusions of sheep blood. However, early non-biological approaches from the same period (such as witchcraft and exorcism) were also ultimately harmful, especially when the actions engendered by those approaches became physical (e.g. burning at the stake).

This was not confined to ancient times or primitive cultures. Well into the 20th century biologic psychiatrists used therapeutic approaches which are brutal, even horrifying by today's sensibilities.

In the early 1900s, "scientific hydrotherapy" used techniques based on the latest physiological theories. Physicians in insane asylums redefined the physical control of patients as a legitimate therapeutic activity, including wrapping patients in a wet sheet and tieing them to the bed. By the 1910s, most psychiatric institutions in the United States were using hydrotherapy, and it remained common until the 1940s and 1950s, when it was replaced by electroconvulsive therapy and antipsychotic drugs.[7]

Sterilization was another major intervention introduced in the early 20th century. Today it's difficult to view sterilization as therapeutic, but many state hospital physicians once used it that way, operating under laws passed largely at the urging of a small but influential group of eugenists. California, for example, allowed physicians to sterilize patients "afflicted with hereditary insanity or incurable chronic mania or dementia.[7]

Prefrontal lobotomy was a surgical technique often used on psychiatric patients. It involved cutting the connections to, or simply destroying, the prefrontal cortex.

Although viewed as horrific by modern sensibilities, these early treatments were seen as the only alternative to an uncontrollable, often self-destructive patient. The treatments were sometimes driven by poor medical science and non-medical influence, essentially being government social policy implemented in medical terms.[7]

Early 20th century

Sigmund Freud was originally focused on the biological causes of mental illness. Freud's professor and mentor, Ernst Wilhelm von Brücke, strongly believed that thought and behavior were determined by purely biological factors. Freud initially accepted this and was convinced that certain drugs (particularly cocaine) functioned as antidepressants. He spent many years trying to "reduce" personality to neurology, a cause he later gave up on before developing his now well-known psychoanalytic theories.[20]

Nearly 100 years ago, Harvey Cushing, the father of neurosurgery, noted that pituitary gland problems often cause mental health disorders. He wondered whether the depression and anxiety he observed in patients with pituitary disorders were caused by hormonal abnormalities, the physical tumor itself, or both.[21]

Despite the suspicions that Freud, Cushing, and others had about biological causes being the underpinnings of mental disorders (and hence possible treatments), at the time there were no effective pharmacological or other biological therapies. Asylum physicians of the period used bromides, chloral hydrate, hyoscine, and other drugs to pacify agitated patients, but they did not regard these drugs as "therapeutic". They were chemical restraints; not much better (and sometimes worse) than physical restraints.[18]

The "chemical imbalance" hypothesis

An important point in modern history of biological psychiatry was discovery of modern antipsychotic and antidepressant drugs. Thorazine, an antipsychotic, was first synthesized in 1950, and iproniazid, one of the first antidepressants, was first synthesized in 1957. In 1959 imipramine, the first tricyclic antidepressant, was developed. Research into the action of these drugs led to the first modern biological theory of mental health disorders. Predating these, some evidence indicates limited, non-systematic use of lithium salts as psychiatric drugs in the early 20th century.[19]

The antidepressant effect of iproniazid was discovered accidentally. It was intended to treat tuberculosis, but clinicians noted that tuberculosis patients suffering from depression showed improvement when given the drug. Later studies showed that iproniazid increased synaptic neurotransmitter levels. The discovery that reserpine (a neurotransmitter depletor) induced depression seemed to confirm that neurotransmitter deficiency caused some mental health disorders, including depression.

Based significantly on clinical observations of the above drug results, in 1965 the seminal paper "The catecholamine hypothesis of affective disorders" (Schildkraut JJ) was published. It was essentially the foundation of the "chemical imbalance" theory of mental health disorders, especially depression. It formed much of the conceptual basis for the modern era in biological psychiatry.[22]

The catecholamine hypothesis only dealt with one group of neurotransmitters. Subsequent research broadened the this hypothesis to include serotonin, which was termed the monoamine hypothesis.

Although research has found significant problems with the catecholamine hypothesis (as it was originally formulated), many newer medications (such as fluoxetine and other SSRIs) were developed based on the underlying theories of the hypothesis. The popular presentation of the etiology of depression is still the "chemical imbalance theory", which is generally accepted as an incomplete etiological theory.

Problems with non-biological approaches

From the late 1940s to the early 1970s, mothers were often blamed for "causing" schizophrenia in their children by being overprotective and hostile. This was based mostly on the prevailing psychoanalytic theories of the time, not on science.[23] [24][25] This form of "blaming the victim" caused great guilt and mental anguish, and inhibited seeking biologic therapy once this became available.

During the same period, a non-biologic psychoanalytic approach blamed "refrigerator mothers" for causing autism in their children. This was significantly based on the viewpoints of Psychologist Bruno Bettelheim and Dr. Leo Kanner. Both Betellheim and Kanner were convinced there was no biologic cause for autism. In 1960, Kanner bluntly described such mothers as "just happening to defrost enough to produce a child."[26][25]

These rigid non-biological approaches to psychiatry caused long-lasting harm to families with autistic and schizophrenic children. There is strong evidence today that schizophrenia and autism have significant biological and/or genetic influences.[8] [9][11][27]

Late 20th century

Starting with Prozac (fluoxetine) in 1988, a series of monoamine-based antidepressant medications were approved. These were no more effective than earlier antidepressants, but generally had fewer side effects.[citation needed] Most operate on the same principle, which is modulation of monoamines (neurotransmitters) in the neuronal synapse. Some drugs modulate a single neurotransmitter (typically serotonin). Others affect multiple neurotransmitters, called dual action or multiple action drugs. They are no more effective clinically than single action versions. That most antidepressants invoke the same biochemical method of action may explain why they are each similarly effective in rough terms. Recent research indicates antidepressants often work but are somewhat less effective than earlier thought.[28]

Along with antidepressants, other drugs targeting various mental health conditions were developed: buspirone (Buspar) for general anxiety disorder, lamictal for bipolar disorder, and quetiapine (Seroquel) for schizophrenia. In the case of quetiapine, one study indicated therapeutic benefits within one week of beginning treatment[29]. This suggests a different method of action than neurotransmitter-based antidepressants. The new drugs increased public consciousness over biological psychiatry as a clinical practice.[citation needed]

During this period, brain imaging devices were developed which allowed noninvasive examination of neural function in patients with mental health disorders. With some disorders it appears the proper imaging equipment can reliably detect neurobiological problems which correlate with a specific disorder.[30][31]

Problems with catecholamine/monoamine hypotheses

The monoamine hypothesis was compelling, especially based on apparently successful clinical results with early antidepressant drugs, but even at the time there were discrepant findings. Only a minority of patients given the serotonin-depleting drug reserpine became depressed; in fact reserpine even acted as an antidepressant in many cases. This was inconsistent with the initial monoamine theory which said depression was cased by neurotransmitter deficiency.

Another problem was the time lag between antidepressant biological action and therapeutic benefit. Studies showed the neurotransmitter changes occurred within hours, yet therapeutic benefit took weeks.

To explain these behaviors, more recent modifications of the monoamine theory describe a synaptic adaptation process which takes place over several weeks. Yet this alone does not appear to explain all of the therapeutic effects. [32]

Despite the problems with this theory, recent research still suppports some aspects.[33] However new research indicates different biological mechanisms may underlie some mental health disorders, only indirectly related to neurotransmitters and the monoamine "chemical imbalance theory".

Recent theories

Since the monoamine theory is certainly wrong in its initial formulation, and likely incomplete even in the current form, it would appear that much of biological psychiatry is based on a shaky foundation. However this simplistic viewpoint is itself wrong. Recent research indicates a biological "final common path" may exist which both electroconvulsive therapy[34] and most current antidepressant drugs have in common. These investigations show recurrent depression may be a neurodegenerative disorder, disrupting the structure and function of brain cells, destroying nerve cell connections, even killing certain brain cells, and precipitating a decline in overall cognitive function.[6]

In this new biological psychiatry viewpoint, neuronal plasticity is a key element. Increasing evidence points to various mental health disorders as a neurophysiologic problem which inhibits neuronal plasticity.[35][36][37]

This is called the neurogenic hypothesis of depression. It promises to explain pharmacological antidepressant action[38][39], including the time lag from taking the drug to therapeutic onset, why downregulation (not just upregulation) of neurotransmitters can help depression, why stress often precipitates mood disorders, [40] and why selective modulation of different neurotransmitters can help depression. It may also explain the neurobiological mechanism of other non-drug affects on mood, including exercise, diet and metabolism.[41] Lastly, by identifying the neurobiologic "final common path" into which most antidepressants funnel, it may allow rational design of new medications which target only that final common path. This could yield drugs which have fewer side affects, are more effective and have quicker therapeutic onset.[6]

Drug therapy vs. Psychotherapy

Much research has shown the benefit of a dual approach to mental health problems, combining psychodynamic (talk therapies) and drug therapies.[42][32] Often the medical or pharmaceutical community is blamed for overly emphasizing pharmacological approaches to the exclusion of psychodynamic, diet, nutrition, and lifestyle changes.[citation needed]

However, a key factor is health care and insurance systems, not just the scientific and clinical viewpoint of the medical community. Most clinicians are trained and comfortable with a dual approach, but many health care and insurance programs provide less coverage for psychodynamic therapy; usually they cover the costs of drug therapy more fully.[43][44]

This can bias mental health care toward drug therapy, which does not represent the opinions, preferences or medical judgment of clinicians.

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See also

External links

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