Why Psychiatric Disorders Are Not the Same as Physical Diseases
A great deal of effort has gone into persuading the general population that psychiatric conditions are just like any others: colds, arthritis, and so forth. I have never found this convincing; psychiatric disorders, including organic ones, are precisely what it is that makes us most ourselves. No one boasts that his symptoms are of psychological origin, though any of us may suffer such symptoms.
In 1982, the neurologist and writer Oliver Sacks wrote a book A Leg to Stand On, in which he described an accident while walking in Norway. He injured the tendon of one of his thigh muscles which was repaired by operation; but afterwards he found that he could not walk because he could not move his leg. He had "forgotten" how to do so. In addition, he no longer experienced his leg as part of himself, but as a completely alien object.
In his book, he rejected the hypothesis that his paralysis was hysterical, that is to say by unconscious mental conflict. Rather he preferred to believe that his peripheral nerve and muscle injuries had somehow affected his brain, and therefore his inability to move his leg was not psychological but physical.
In the latest edition of the Journal of Neurology, Neurosurgery and Psychiatry, three neuroscientists, including a neurologist and a psychiatrist, reinterpret Sacks’ symptoms and say that they were indeed psychogenic, or what used to be called hysterical. They say that his pattern of symptoms was incompatible with a purely neurological explanation, indeed that they were typical of hysterical paralysis, though they emphasize that this does not mean in the least that they were "fake" or "imaginary." As a 19th century doctor put it of female patients with hysterical paralyses (most patients with such paralyses were female): "She says, as all such patients do, ‘I cannot’; it looks like ‘I will not’; but it is ‘I cannot will.'’’