Mood instability and psychosis: analyses of British national survey data.

BACKGROUND: We used British national survey data to test specific hypotheses that mood instability (1) is associated with psychosis and individual psychotic phenomena, (2) predicts the later emergence of auditory hallucinations and paranoid ideation, and (3) mediates the link between child sexual abuse and psychosis. METHODS: We analyzed data from the 2000 and 2007 UK national surveys of psychiatric morbidity (N = 8580 and 7403, respectively). The 2000 survey included an 18-month follow-up of a subsample (N = 2406). Mood instability was assessed from the Structured Clinical Interview for DSM-IV Axis II (SCID-II) questionnaire. Our dependent variables comprised auditory hallucinations, paranoid ideation, the presence of psychosis overall, and a 15-item paranoia scale. RESULTS: Mood instability was strongly associated in cross-sectional analyses with psychosis (2000: OR: 7.5; 95% CI: I 4.1-13.8; 2007: OR: 21.4; CI: 9.7-41.2), paranoid ideation (2000: OR: 4.7; CI: 4.1-5.4; 2007: OR: 5.7; CI: 4.9-6.7), auditory hallucinations (2000: OR: 3.4; CI: 2.6-4.4; 2007: OR 3.5; CI: 2.7-4.7), and paranoia total score (2000: Coefficient: 3.6; CI: 3.3-3.9), remaining so after adjustment for current mood state. Baseline mood instability significantly predicted 18-month inceptions of paranoid ideation (OR: 2.3; CI: 1.6-3.3) and of auditory hallucinations (OR: 2.6; CI: 1.5-4.4). Finally, it mediated a third of the total association of child sexual abuse with psychosis and persecutory ideation and a quarter of that with auditory hallucinations. CONCLUSIONS: Mood instability is a prominent feature of psychotic experience and may have a role in its genesis. Targeting mood instability could lead to innovative treatments for psychosis.