ABSTRACT
I HOPE it will not be a waste of time to begin by seeing what can be meant by prognosis in this difficult kind of illness. Prognosis is often conceived as the natural history of disease—or the course it will follow if it is not interfered with. Treatment is valued for the good modification it produces in this ‘natural’ course of events; it may hurry up the processes of recovery or it may bring about recovery that would not otherwise occur, or it may lessen the harm the disease does; in other words, the efficacy of treatment is assessed by the changes produced in the time the illness takes and the shape it takes. In the case of such a disease as malaria, this conception of prognosis, and this use of it for assessing treatment, can be demonstrated. In psychiatry, however, one is not as a rule dealing with parasites, bacteria, or other exogenous agents which live and exert their influence in a definite order of time and place. Causes of mental illness have no set sequence or constancy. Those external to the patient are as variable and manifold as the pattern of daily life around us and those intrinsic in him are seldom capable of forcing their way and becoming manifest as illness, no matter what befalls the patient. They are for the most part dependent on circumstance, and of their particular transmission and manifestation we know little; we infer hereditary and constitutional causes with good grounds, but of the details of heredity in any of the individual forms of mental illness we cannot be sure. Consequently we cannot find now any accuracy of prognosis, in the sense of predictable sequence in an individual, based on comparable experience of many others; the variations will be too many; we may expect such accuracy when we know more of the nature and mode of transmission, and of the influence of external circumstances upon time and form and degree of manifestation of each kind of mental illness. Without accurate knowledge of how the causal and modifying factors act, prognosis must be uncertain to a greater extent than in many other illnesses. In medicine, it is true, prognosis can hardly ever be exact, but here it is more inexact than usual.
