Behavioral-assay Technics - Chemical Bases Of Behavior
Still another approach to the study of biochemical factors in mental disorders is what might be termed behavioral-assay technics. For example, it has been found that the injection of various extracts of blood taken from schizophrenic patients into laboratory animals sometimes causes behavioral alterations. When proper experimental controls are used in such studies, the observations suggest that the blood extract or other material taken from the patient contains substances of some kind involved in the etiology and pathogenesis of the disorder under study. Some isolation and identification of the abnormal substance can then be attempted by using the kind and magnitude of behavioral changes induced by test preparations as the assay technic. Empirical researches of this kind have yielded some promising leads. Several examples will be briefly described.
A few years ago the group headed by Dr. Heath at Tulane University reported a substance they extracted from the serum of schizophrenic patients and termed taraxein. When this material was injected into monkeys, profound behavioral changes were observed which resemble the condition, catatonia, sometimes seen in schizophrenic patients. There was a paucity of skeletal muscle movement and the extremities remained fixed in various positions in which they were placed (34). The group injected the same material into 20 human subjects and again described symptoms reminiscent of schizophrenia. Taraxein has not been identified chemically but is believed to be a euglobulin. The same group reported also that the rapid injection of 450 ml. of plasma collected from schizophrenic patients produced in 4 prisoner volunteers behavioral changes characteristic of schizophrenia (35). Many groups have attempted to replicate these fascinating results, both with blood plasma and a blood extract obtained by the procedure described by Heath. However, most of these attempts have ended in failure and the uniqueness of the results reported by the Tulane group remains an enigma (50, 64).
Other empirical researches involving the plasma of psychotic individuals have focused on more objective and quantifiable behavioral alterations. For example, Winter and Flataker (73) describe a procedure in which a 1 ml. aliquot of human plasma is injected intraperitoneally into rats who have been trained to climb a rope 172 cm. high. Rats injected with plasma from psychotic patients take longer to ascend the rope than those injected with plasma from normal control subjects. This effect has been replicated in several laboratories. The active factor of the plasma has been concentrated to some extent but not yet identified (38).
Among a variety of other perhaps more exotic behavioral-assay technics has been the injection of serum into spiders of the species Zilla-x-Notata. Serum from patients with the symptoms of catatonic schizophrenia often causes spiders' webs to be rudimentary and poorly formed. This effect is rarely seen with sera from patients with other disorders or normal control subjects (6).
The meaning of behavioral alterations induced in these tests is difficult to evaluate. They do not mean, of course, that mental illnesses are necessarily caused by biochemical lesions. However, the fact that the blood or other bodily fluids of patients with certain mental disorders can be differentiated from that of normal controls by these means does suggest the possibility of a biologic difference in these disorders at the biochemical level. The purification, isolation, and, ideally, identification of the active factors in the tests hold promise of further knowledge of the biologic mechanisms in disturbed mental states.
Much progress has been made in recent years toward a better understanding of the chemical bases of behavior. Progress has been made especially in some problems of particular relevance to psychiatry and general medicine: anxiety, a common denominator of most emotional disorders, and psychosis. In this brief overview, problems of particular relevance to psychiatry and general medicine such as anxiety and the nature of psychosis were emphasized.
The discovery of biochemical alterations in persons with various mental disorders is a particularly promising development. These findings should not be construed to mean that mental disorders are simply the result of primarily biochemical lesions. There is a mass of evidence that other classes of variables, some biologic and some psychologic or social, bear greatly on the problem also. In some psychiatric disorders it may be, for example, that certain life experiences, or patterns of living, occurring with sufficient frequency or intensity or at critical periods of biosocial development, activate metabolic aberrations for which sufficient genetic soil exists. The failure of maturation of some enzymatic systems due to experiential factors may limit the individual's capacity to react adaptively in the course of ordinary life stresses or, in other cases, to react adaptively in response to extraordinary stresses of a physical, psychologic, or social nature. Finally, the characteristics of some disorders, in terms of manifest symptoms, may be related chiefly to experiential, social, and cultural factors, even when biochemical abnormalities are of primary etiologic significance.