Mood instability shapes psychotic experiences

By Lucy Piper, Senior medwireNews Reporter

Mood instability (MI) is a prominent feature of psychosis, say researchers who found it was associated with and predicted the presence of psychotic experiences such as paranoid ideation and auditory hallucinations.

“MI may be an epiphenomenon, but it might equally have a central role in the formation and maintenance of symptoms of psychosis,” say the study authors Paul Bebbington (University College London, UK) and colleagues. “If so, it could provide explanations both for the origins of psychotic phenomena and for the fluctuations so commonly observed in them.”

The findings come from analyses of two UK national surveys of psychiatric morbidity conducted in 2000 and 2007 that captured responses from a total of 15,983 individuals.

According to cross-sectional analyses, patients who responded yes to the question: “Do you have a lot of sudden mood changes?” were a significant 1.99 and 8.11 times more likely to have psychosis in 2000 and 2007, respectively, than individuals without MI. This was after taking into account current dysphoric mood disturbance and hypomanic mood.

In terms of specific psychotic experiences, MI was significantly associated with both paranoid ideation (odds ratio [OR]=2.3 for both surveys) and auditory hallucinations (OR=1.6). And people with MI were significantly more likely to have higher paranoid ideation scores than those without MI.

In addition to being associated with such experiences, MI predicted the future onset of these psychotic experiences. In longitudinal analyses of data from the 2000 survey for a sub-sample of 2406 individuals followed up over an 18-month period, patients with MI at baseline had a 2.3 times greater odds of developing paranoid ideation and a 2.6 times greater odds of developing auditory hallucinations than patients without MI.

After controlling for baseline dysphoric mood disturbance, the risk remained significant for paranoid ideation, but not for auditory hallucinations. MI also increased the likelihood of paranoia still being present at follow-up but not that of auditory hallucinations. This may be related to the sporadic nature of hallucinations, the researchers suggest.

MI also played a mediating role in the association between childhood sexual abuse and psychosis, accounting for over a third of the total effect for psychosis and persecutory ideation, and a quarter of the total effect for auditory hallucinations.

“Although unpleasant and threatening psychotic experiences and thoughts might well lead to proportionate fluctuations in mood, our findings argue that MI is part of the psychotic process, whether as antecedent, concomitant, or consequence,” Bebbington and colleagues report in Schizophrenia Bulletin.

They therefore suggest that “direct therapeutic targeting of MI may reduce the propensity to recrudescence of psychotic symptoms.”

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