Technology always produces new directions for research, and when it became possible to do genetic testing, psychiatry became committed to finding the genetic causes of mental illness. Finding a genetic link seemed particularly relevant for schizophrenia, a fairly common (affecting about 1 percent of the population), severe, and perplexing form of mental illness and one that clearly runs in families. And yet after thirty years and millions upon millions of dollars’ worth of research, we have failed to find consistent genetic patterns for schizophrenia – or for any other psychiatric illness, for that matter. Some of my colleagues have also worked hard to discover genetic factors that predispose people to develop traumatic stress. That quest continues, but so far it has failed to yield any solid answers.
Recent research has swept away the simple idea that “having” a particular gene produces a particular result. It turns out that many genes work together to influence a single outcome. Even more important, genes are not fixed; life events can trigger biochemical messages that turn them on or off by attaching methyl groups, a cluster of carbon and hydrogen atoms, to the outside of the gene (a process called methylation), making it more or less sensitive to messages from the body. While life events can change the behavior of the gene, they do not alter its fundamental structure. Methylation patterns, however, can be passed on to offspring – a phenomenon know as epigenetics. Once again, the body keeps the score, at the deepest levels of the organism.
Bessel van der Kolk – The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma p.151
Psychiatry, as as subspecialty of medicine, aspires to define mental illness as precisely as, let’s say, cancer of the pancreas, or streptococcal infection of the lungs. However, given the complexity of mind, brain, and human attachment systems, we have not come even close to achieving that sort of precision. Understanding what is “wrong” with people currently is more a question of the mind-set of the practitioner (and of what insurance companies will pay for) than of verifiable, objective facts.
Bessel van der Kolk – The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma p.137
After this first point has been established our psychiatric interest will become even livelier. If a delusion is not to be got rid of by a reference to reality, no doubt it did not originate from reality either. Where else did it originate? There are delusions of the most varied content: why in our case is the content of the delusion jealousy in particular? In what kind of people do delusions, and especially delusions of jealousy, come about? We should like to hear what the psychiatrist has to say about this; but at this point he leaves us in the lurch. He enters into only a single one of our enquiries. He will investigate the woman’s family history and will perhaps give us this reply: ‘Delusions come about in people in whose families similar and other psychical disorders have repeatedly occurred.” In other words, if this woman developed a delusion she was predisposed to it by hereditary transmission. No doubt this is something; but is it all we want to know? Was this the only thing that contributed to the causation of the illness? Must we be content to suppose that it is a matter of indifference or caprice or is inexplicable whether a delusion of jealousy arises rather than any other sort? And ought we to understand the assertions of the predominance of the hereditary influence in a negative sense as well – that no matter what experiences this woman’s mind encountered she was destined some time or other to produce a delusion? You will want to know why it is that scientific psychiatry will give us no further information. But my reply to you is ‘he is a rogue who gives more than he has.’ The psychiatrist knows no way of throwing more light on a case like this one. He must content himself with a diagnosis and a prognosis – uncertain in spite of a wealth of experience – of its future course.
Sigmund Freud – Introductory Lectures on Psychoanalysis p.310