Reflections From A Chair

The Independent reports on a new study of the genetics involved in schizophrenia and bipolar disorder.

The article, Unlocked: the secrets of schizophrenia, covers three studies published in the journal Nature.

Here are some of the results:

• “Scientists have discovered a remarkable similarity between the genetic faults behind both schizophrenia and manic depression”
• “thousands of tiny genetic mutations – known as single nucleotide polymorphisms (SNPs) – are operating in raising the risk of developing the illness.”
• “Each mutation on its own increased the risk of developing schizophrenia by about 0.2 per cent but collectively they were found to account for at least a third of the total risk of developing schizophrenia.”
• “Some of the genetic variations associated with schizophrenia appear to occur within a region of the genome known to be involved in controlling the immune system. This might help to explain why babies born in winter and spring when influenza is rife, or to women who have had flu during pregnancy, are at slightly increased risk of developing schizophrenia in later life, the scientists said.”
• “Some of the genetic variations associated with schizophrenia appear to occur within a region of the genome known to be involved in controlling the immune system. This might help to explain why babies born in winter and spring when influenza is rife, or to women who have had flu during pregnancy, are at slightly increased risk of developing schizophrenia in later life, the scientists said.”

It’s actually that first point that has me rethinking some of my beliefs. Specifically, I am reviewing my disdain for the diagnostic category of Schizoaffective Disorder. Till today, I generally considered that disorder to be an overly broad, sloppy diagnosis best used by people who can’t make up their mind about what is the real diagnosis.

eMedicine’s discussion of the disorder notes that “Making the diagnosis of schizoaffective disorder can be difficult because it encompasses 2 other diagnostic entities, namely schizophrenia and mood disorders. An accurate diagnosis is made when the patient meets criteria for major depressive disorder or mania while also meeting the criteria for schizophrenia.”

However, as the Mayo Clinic’s website phrases it: “Not all experts agree that schizoaffective disorder should be treated as a distinct disorder. Some regard the condition simply as schizophrenia with some mood symptoms…”

Or as Hales and Yudofsky put it in Essentials of Clinical Psychiatry,

• “Investigators have found the interrater reliability of the DSM-IV schizoaffective disorder diagnositic category to be low.” [In other words, trained clinicians do not often make this diagnosis for the same patient.]
• “The validity of the schizoaffective disorder construct, as well as its division into depressive and bipolar subtypes, has also been questioned.”

Being less generous than those authors, I have long believed that schizoaffective disorder was used by clinicians when they did not take enough time (or interest) to fully evaluate the patient. To cover all possible bases, schizoaffective disorder could be used.

However, in light of this recent research, maybe I should be eating some humble pie for breakfast.

If there are “thousands of tiny genetic mutations” common to and underlying both schizophrenia and bipolar disorder, then it could be expected that the expression or result of those mutations could be varied and diverse among individuals. A third “fuzzy” category of schizoaffective disorder may well cover the middle ground between the two more “pure” categories.