In an area which carries large zones of ignorance, it may be well to talk around a topic. While that may serve a purpose of the speaker or writer's convenience, there may be a more constructive purpose: that of opening up heuristic speculations; they often lead to findings.
In some ways the above may be said of this book. Also, as the book is concerned with the physical aspects of anomalies which manifest themselves in the mental sphere, perhaps it should not be expected to be holistically oriented, ie, also concerned with behavioral or cultural aspects which are believed by some to be causal and others to be associated with disturbances of mental function. The title clearly expresses the physical or biochemical aspect or bias. In fact, as stated in the preface to the book, the aim of research in mental health is to recognize inborn cellular errors of metabolism