Subclinical psychosis rarely troublesome
medwireNews: Subclinical psychotic symptoms are quite common in the general population, but rarely cause distress, a study shows.
Lifetime rates of symptoms of thought disorder, ego disorder, hallucination, and schizotypy ranged from 1.2% to 18.1% in a population-based sample of Swiss men and women. The 12-month prevalence ranged from 0.5% to 16.1%.
"By focusing on sub-threshold syndromes, we have presented evidence for sub-clinical psychosis symptoms that are quite common in the general population," the researchers write in European Psychiatry.
They add that "our data support the notion of a continuity of psychotic symptoms with normal experiences."
The study participants were 144 men and 191 women who underwent a series of interviews with clinical psychologists between 1978 and 2008, by which point they were aged 49-50 years.
The syndrome with the highest prevalence was schizotypy, with lifetime and 12-month rates of 28.2% and 25.9%, respectively. This was mostly because of the high proportion of participants reporting to have "ideas that others don't share with you," at respective lifetime and 12-month rates of 18.1% and 16.1%, and also to "believe others are to blame for most of your troubles," and to "suddenly identify hidden reasons for trivial events," with rates ranging from 5.1% to 8.9%.
Schizotypy was also the most distressful syndrome, with a 6.6% rate of severe symptoms, compared with 0.1-2.2% for the other syndromes.
The least common syndrome was ego disorder, with lifetime and 12-month rates of 4.8% and 3.0%, respectively. The corresponding rates were 9.7% and 5.3% for hallucinations and 10.6% and 6.3% for thought disorder.
Thought disorder corresponds to disorganization, while ego disorder and hallucinations represent positive symptoms, say lead researcher Wulf Rössler (University of Zurich, Switzerland) and co-workers.
They used the Structured Psychopathological Interview and Rating of the Social Consequences of Psychological Disturbances for Epidemiology (SPIKE) to gauge the participants' symptoms, so did not assess negative symptoms because "it is very difficult to differentiate reliably between negative and depressive symptoms in a clinical interview that covers a broad range of symptoms."
The team concludes: "Thus, one finds in sub-clinical psychosis typical syndromes similar to those known from full-blown psychosis, but in an attenuated form."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Eleanor McDermid, Senior medwireNews Reporter