290 (items G1–G13, G15, G16, G20, G21). These concern classic psy- chotic symptoms involving, for example, thought interference and passivity phenomena, persecution and auditory hallucinations. All these items can be rated in six ways: ‘1’, no symptom; ‘2’, symptom present but not clinically relevant (not bothered by it and not seeking help for it); ‘3’, symptom result of ingestion of drugs/ medication; ‘4’, symptom result of a somatic disease; ‘5’, true psychiatric symptom causing distress or help-seeking behaviour; ‘6’, symptom may not really be a symptom because there appears to be some plausible explanation for it. In order to verify symptom presence and their clinical relevance, clinical re-interviews were conducted over the telephone by a senior registrar in psychiatry for all individuals who had at least one rating of 5 or 6, using single questions from the Structural Clinical Interview for DSM-III-R (SCID), an instrument with proven reliability and validity in diagnosing schizophrenia [59]. CIDI ratings of ‘5’ and ‘6’ were corrected on the basis of these clinical interviews. Life-time depression was assessed using the 28 items of the CIDI core depression section (E) with exclusion of four items related to dysthymia. Life-time mania was assessed using the 11 items of the CIDI core mania section (F). All these items can be rated as either ‘yes’ (1) or ‘no’ (0). Symptoms of depression (e.g., anhedonia) had to be present for at least 2 weeks, manic symptoms (e.g., persis- tently elevated, expansive or irritable mood) had to be present for at least two days. In order to make a DSM-III-R diagnoses, the CIDI assesses whether the mood symptoms and other symptoms were present within the same time period [48]. Neuroticism was assessed at baseline with the 14-item Groningen Neuroticism Scale [42]. Family history of depression and psychosis was examined at T1, by asking the subject whether any of his ﬁrst degree biological rela- tives had ever experienced depressive symptoms and/or delusions or hallucinations, providing descriptions of these. Family history of treated depression and psychosis was examined at T1, by asking the subject whether the affected ﬁrst degree biological relatives had ever received medical or psychological help for these symptoms. Urbanicity was coded as rural if a municipality had fewer than 500 addresses per square kilometre and urban otherwise. Single living status was assessed by asking the subject whether or not he per- manently shares a household with someone else, irrespective of ownership. Visual or auditory impairment was scored as present if respondents self-reported such a condition being treated or mon- itored by a physician in the 12 months before T0. j Statistical analysis For the current investigation, two outcome measures were created. First, all subjects with broadly deﬁned psychosis-like experiences (CIDI ratings of ‘2’, ‘3’, ‘4’, ‘5’ and ‘6’) at T1 or T2 were included in the analyses if they had not displayed such symptoms at T0 (hereafter: broad psychosis outcome). This outcome was rated as either present (=‘1’) or absent (=‘0’). For the second outcome, only subjects who reported narrowly deﬁned clinically relevant psy- chotic symptoms (CIDI ratings of ‘5’) were included if they had had no evidence of psychosis at T0 (hereafter: narrow psychosis out- come). This outcome was similarly scored as either present (=‘1’) or absent (=‘0’). Subjects were then divided into three age groups of young (18–34 years), middle (35–49 years) and old age (50– 64 years). Contrasts were expected to show up most powerfully in the comparisons between the youngest and oldest age groups, thus the analysis has this contrast as its focus. In order to test for contributions of different sets of risk factors to the psychosis outcome, a general linear modelling (GLM) strategy was applied. Interaction effects were analysed using the BINREG procedure in STATA [60], a GLM extension for the binomial family. Interaction effects between age group and categorical or dummy coded expo- sure variables were estimated under an additive model [15] yielding risk difference effect sizes. Cumulative incidences of psychosis outcome at T1 and/or T2 were calculated in subjects with absence of the narrow psychosis outcome at baseline (risk set: n = 4,637) and in subjects with absence of the broad psychosis outcome (risk set: n = 4,041). Cumulative incidence rates across age groups were Table 1 Characteristics of the NEMESIS sample at the one-year follow-up measure Mean age Female sex Education (in years) 0–11 12 13–15 16+ Single Urban Sensory deficits Hearing impairment Visual impairment Total number Age groups (%) Young Middle 27.7 55.6 17.1 40.4 9.2 32.3 56.4 83.4 1.4 0.7 1,891 41.6 50.8 25.2 35.8 7.3 30.7 14.9 81.4 2.2 1.2 2,198 Old 56.7 54.7 37.0 33.1 5.9 22.3 6.2 83.4 3.9 2.5 1,527 Total sample 41.2 53.5 25.7 36.6 7.6 28.9 26.5 82.6 2.4 1.4 5,616 compared by means of Pearson v2 tests. A post-hoc analysis was performed for ﬁrst contact rates. All data were analysed using the STATA program, version 9.1 [60]. Results Table 1 lists the demographic characteristics of the sample participating in the follow-up at T1 and/or T2. No differences existed for urbanicity (v2 = 3.78, df = 2, p = .151) across groups. Differences emerged for level of education (v2 = 44.14, df = 2, p < .001), single living status (v2 = 1300, df = 2, p < .001), and visual and auditory impairment (v2 = 19.47, df = 2, p < .001 and v2 = 24.34, df = 2, p < .001, respectively) with older subjects having had less higher education than the young and the middle group, living alone more often and reporting sensory impairment more often. The male:female ratio also differed across groups with women being somewhat overrepresented in the young and old group (v2 = 10.92, df = 2, p = .004). j Cumulative incidence At T1 or T2, 56 out of 4,637 individuals with no psy- chosis at baseline had the narrow psychosis outcome. Of all these incident psychosis, 19 were in the young group (34%), 25 in the middle group (44%) and 12 in the old group (21%). The cumulative incidence of LOP was 0.3%. This rate was comparable to the cumulative incidence rate of EOP (0.4%) and MOP (0.4%) (v2 = 1.19, df = 2, p = .55). Out of 4,401 subjects without any self-reported psychotic experiences in the past, 132 had developed the broad psychosis outcome at T1 or T2. Fifty-one of these were in the young group (38%), 54 were in the middle group (42%) and 27 (20%) were in the old group. The cumulative incidence for the broad psychosis outcome was 0.8% in the old group, 1.3% in the young group and 1.1% in the middle group (v2 = 4.66, df = 2, p = .097).