Objective: To examine the extent to which neuroscience accounts for mental disorders.
Method: Relevant literature on this problem was selectively reviewed.
Results: Thus far, neuroscience research has contributed more to the understanding of the brain than to determining the causes of mental disorders. Its model is more appropriate to severe than to common mental disorders. A reductionistic approach cannot account for emergent phenomena occurring at the level of the mind.
Conclusions: Mental disorders cannot be reduced to abnormalities in neuronal activity; psychiatric symptoms need to be understood at multiple levels.
Can J Psychiatry. 2009;54(8):513-517.
* Neuroscience research has attempted to explain psychopathology at a cellular level.
* However, this approach has not, in any way, accounted for the causes of mental disorders.
* Mental symptoms are emergent phenomena that are a function of the mind, and cannot be reduced to the activity of neurons.
Key Words: psychiatry, neuroscience, reductionism
In 2005, 2 leaders of psychiatric research in the United States and Canada wrote an article in the Journal of the American Medical Association (JAMA) suggesting that psychiatry should redefine itself as a clinical discipline concerned with applied neuroscience.1 This point of view would reduce the complexity of the mind to physiological and biochemical pathways, and limit psychosocial influences to a role as precipitants of disorder. Psychiatry would no longer differ from other branches of medicine.
My review will critically examine the critical assumptions behind these conclusions. Can the mind be reduced to the brain? Can the symptoms that psychiatrists treat be understood at the neural or molecular level?
The Separation of Psychiatry and Neurology
Consistent with their view of mental illnesses as brain disorders, the authors of the JAMA article1 joined previous writers2,3 in making the recommendation that psychiatry and neurology should reunite into one specialty.
How did psychiatry become a discipline in its own right? In the early part of the 19th century, physicians who treated mental illness were not usually called psychiatrists.4-6 If they worked in mental hospitals, they might have been called alienists. Even in the early 20th century, practitioners usually called their specialty neuropsychiatry or psychological medicine.6 Sigmund Freud, a trained neurologist, treated neurotic symptoms but never called himself a psychiatrist.
The identity of psychiatry as a separate medical specialty emerged in the course of the 20th century. The American Psychiatric Association, founded in 1844, only adopted its present name in 1922,7 and the Canadian Psychiatric Association was founded as recently as 1951.
Psychiatry grew and became more distinct as it was no longer practiced only in mental hospitals. The specialty became independent and gained influence with the public at large.8 After the Second World War, most general hospitals opened wards and clinics for patients with mental disorders. This change reduced isolation, as practitioners were now in direct contact with their medical colleagues. Concurrently, psychiatry was being practiced in offices outside of hospitals.
However, the conceptual basis for considering psychiatry distinct from neurology took a long time to develop. Ultimately this depended on a distinction between mental illness and brain disorders. Psychiatrists treat diseases that primarily affect mental processes. While strokes can also disturb the mind, producing changes in mood, behaviour, and cognition, their most typical and dramatic effects are on motor and sensory function. Dementia, which produces primarily mental symptoms, has remained on a boundary between psychiatry and neurology.
Moreover, while neurology can map diseases in the brain, psychiatry has thus far been unable to do so. …