Self-disorders highly specific to schizophrenia spectrum

By Joanna Lyford, Senior medwireNews Reporter

Self-disorders – also known as anomalous self-experiences – are highly specific to individuals with schizophrenia-spectrum disorders, Danish research indicates.

The study found that self-disorders aggregated selectively among people with schizophrenia, nonaffective forms of psychosis and schizotypal disorders, and were less prevalent in people with other psychiatric diagnoses.

Julie Nordgaard and Josef Parnas, both from the University of Copenhagen, enrolled 100 consecutive patients admitted to a psychiatric unit. Forty-six of the patients were diagnosed with schizophrenia or nonaffective psychosis, 22 were diagnosed with schizotypal disorder, and 32 received other psychiatric diagnoses (eg, bipolar disorder, major depression).

Self-disorders were assessed using the Examination of Anomalous Self-Experiences (EASE) interview, which gives points for features such as pressure of thought, loss of thought ipseity, thought block, ruminations, obsessions and perceptualisation of inner speech or thought.

The median EASE scores were 19.63 for patients with schizophrenia or nonaffective psychosis, 17.82 for those with schizotypal disorder and 8.06 for those with other diagnoses.

Thus, self-disorders, as assessed using the EASE, clearly aggregate within the schizophrenia spectrum, say the authors in Schizophrenia Bulletin.

EASE scores significantly correlated with schizophrenic symptomatology, with the strongest correlation being for negative symptoms and formal thought disorder. Furthermore, the EASE scale showed excellent internal consistency and the five EASE domains combined accounted for 59.8% of the total variance.

Based on their observations, the authors hypothesise that self-disorders are “an experiential vulnerability phenotype specific to the schizophrenia spectrum disorders”.

They write: “Apart from the currently investigated clinical potential of [self-disorders] for early detection and early differential diagnosis, [self-disorders] merit attention as a potential target phenotype for neurobiological research and may come to play a significant role in conceptualizing the neurodevelopmental processes implicated in the onset of schizophrenia.”

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