You are here
Schizophrenia Research: The Necessary Link between Psychopathology and Clinical Neuroscience
Interview with Andreas Erfurth, recorded at ECNP Congress 2016, Vienna
Interview with Dr Andreas Erfurth on Schizophrenia Research: The Necessary Link between Psychopathology and Clinical Neuroscience
I think this is a very interesting topic coming from a generation that started with ICD-9 and now we have ICD-10 and we will have the ICD-11 at some point. Now we have the DSM-5 and through all our life we were accompanied by this diagnosis of schizophrenia.
Of course we have many patients that clearly fit into the description of schizophrenia that meet the criteria for the definitions of schizophrenia but one of the main questions is do we have enough data to support that actually schizophrenia is a disease entity that should be separated, for instance from major depressive insanity, bipolar disorder as we call it today or would other models be more suitable to what we find from a genetic and also from a clinical point of view and of course the main model would be the unitary model of psychosis that was proposed in the 19th Century essentially by Griesinger and others.
The history of psychiatry over the last 150 years was always characterised by these two possibilities and it was only in 1899 with Emil Kraepelin’s description of dementia praecox as opposed to manic depressive insanity, then the introduction of the word of schizophrenia, more accurately of the group of schizophrenias by Manfred Bleuler that essentially the 20th Century was very much occupied by this idea that we have a true dichotomy of two different diagnostic entities.
On the one hand, those patients with dementia praecox, and I use the Kraepelinian word because it describes so well what the main difference of the concept was as opposed to manic depressive insanity.
It was not the idea of any psychopathological features during the episode; it was the outcome and I think that we can understand Kraepelin better if we think about his time and he had no possibilities of treating patients like we have today with pharmacology and other possibilities.
Essentially the prognosis was very important and the decision to take ‘Is this is a patient that will eventually be overwhelmed by his cognitive dysfunction and develop dementia praecox or will this be a person that’, and we are talking about the beginning of the 20th Century ‘will be able to go back to his working place, go back to continue with his work at home?’ and this was probably the main characteristic of the dichotomy.
But on the other hand, as I said, there were always psychiatrists in every generation that focussed on the possibility that maybe it’s not too different disease entities but it is just one disease, probably the most influential being Klaus Conrad in Germany.
On the other hand there have been other psychiatrists who have said no, probably we do not need two diagnoses; we need even more diagnoses like Leonhard who at the end had dozens of different diseases or disorders that he described.
Now we have with DSM-5, somehow DSM-5 tries to continue. On the one hand we have the division between the group of schizophrenia or related disorders and the group of the affective disorders and somehow DSM does not really reflect the data that we have for instance from genetics or also from pharmacology that show that there is a huge overlap. If we think about treatment, there is no single drug that we can use to treat acute schizophrenia that we cannot use for the treatment of acute mania. There is a 100% overlap.
The other way round, there is one exception which is lithium but there is a very, very high overlap.
The same is true for genetics. If we look at the vulnerability or the heritability by SNPs, then we see that yes, it’s true 23% of schizophrenia heritability can be explained by SNPs, but if we look at these 23%, 15% of these 23% can be explained by SNPs that we can also find typically for bipolar disorder, so there is only an 8% on top which seemed to be specific for those people who meet the criteria for schizophrenia.
We have a lot of data and this was just one example that would support that it is more a continuum between a clinical state that at the end of the day we can say yes, this is dementia praecox as Kraepelin has described more than 100 years ago and yes, this is a cause of a manic depressive illness with clear free intervals in-between and these are two different types. But why are we not using specifiers? Why are we not saying ‘This is Griesinger’s unitary psychosis’ and we have specifiers for different causes, so that could be an alternative?
If we think on how huge the changes in diagnosis have been during our careers and during our lives, when I was a young man we still used to diagnose with ICD-9 which means we made the diagnosis of anxiety neurosis, we made the diagnosis of neurotic depression, we made the diagnosis of homosexuality as psychiatric diagnosis and for the young residents, this is unthinkable.
My question is maybe in 25 years people will say maybe DSM-5 still has schizophrenia and with DSM-6 we are now going into a new direction, we have more a spectrum disorder, a unitary spectrum of psychosis with certain specifiers.
We don’t know. Of course we need more data. We need more data from neuroscience, from genetics, we need of course more specific data that we collect right now even more open-minded because when we collect scientific data starting from the idea that we have two disease entities that are completely distinct, then of course this is an error in our thinking to start with.
I am very much looking forward to the next ten or 20 years of psychiatry and to see whether we will find an answer, whether Griesinger or Kraepelin was right.