gained using imaging techniques, psychopharmacology, neuroimmunochemistry and so on. Discovering the detailed interplay between neurotransmitters and the understanding of the neurotransmitter fingerprint of psychiatric drugs such as clozapine has been a helpful result of the research. 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, such as drugs, diet, avoidance of environmental contaminants, exercise, and alleviation of the adverse effects of life stress, all of which can cause measurable biochemical changes. 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 talk therapies. Medical psychiatric training generally includes psychotherapy and biological approaches. Accordingly, psychiatrists are usually comfortable with a dual approach: "psychotherapeutic methods […] are as indispensable as psychopharmacotherapy in a modern psychiatric clinic". Basis for biological psychiatry Sigmund Freud developed psychotherapy in the early 1900s, and through the 1950s this technique was prominent in treating mental health disorders. However, in the late 1950s, the first modern antipsychotic and antidepressant drugs were developed: chlorpromazine (also known as Thorazine), the first widely used antipsychotic, was synthesized in 1950, and iproniazid, one of the first antidepressants, was first synthesized in 1957. In 1959 imipramine, the first tricyclic antidepressant, was developed. Based significantly on clinical observations of the above drug results, in 1965 the seminal paper "The catecholamine hypothesis of affective disorders" was published. It articulated the "chemical imbalance" hypothesis of mental health disorders, especially depression. It formed much of the conceptual basis for the modern era in biological psychiatry. The hypothesis has been extensively revised since its advent in 1965. More recent research points to deeper underlying biological mechanisms as the possible basis for several mental health disorders. Modern brain imaging techniques allow noninvasive examination of neural function in patients with mental health disorders, however this is currently experimental. With some disorders it appears the proper imaging equipment can reliably detect certain neurobiological problems associated with a specific disorder. If further studies corroborate these experimental results, future diagnosis of certain mental health disorders could be expedited using such methods. Another source of data indicating a significant biological aspect of some mental health disorders is twin studies. Identical twins have the same nuclear DNA, so carefully constructed studies may indicate the relative importance of environmental and genetic factors on the