Table 1.
Sample clinical and demographic characteristics showing that there were no group differences between healthy volunteers and first episode psychosis patients in age, sex, ethnicity, socio-economic status, body mass index, cannabis, alcohol or tobacco use.
| Healthy volunteers | First episode psychosis patients | t/x2/U | df | p | |
|---|---|---|---|---|---|
| N | 35 | 31 | |||
| Age mean (SD), years | 27.12 (5.32) | 26.64 (4.68) | t = 0.52 | 64 | 0.60 |
| Sex (male/female) | 26/9 | 26/5 | x2 = 1.18 | 2 | 0.55 |
| Ethnicity (Caucasian/Black African or Black Caribbean/ Asian/ Mixed/missing) | 15/3/11/4/2 | 12/0/6/3/0 | x2 = 8.49 | 6 | 0.20 |
| Years of education after compulsory education mean (SD)a | 4.01 (3.81) | 3.01 (2.59) | t = 1.63 | 58 | 0.11 |
| Socio-economic status (high/medium/ low/unemployed/ student/missing data)b | 3/4/10/1/13/4 | 1/2/13/5/7/3 | x2 = 24.38 | 20 | 0.23 |
| Body mass index mean (SD) score | 25.12 (3.81) | 25.65 (5.10) | t = −0.41 | 46 | 0.68 |
| Current cannabis use (yes/no) | 0/35 | 0/31 | NA | NA | NA |
| Current alcohol use (yes/no/missing data) | 21/12/2 | 17/13/1 | x2 = 2.88 | 4 | 0.60 |
| Current tobacco use (yes/no/ missing data) | 10/23/2 | 13/17/1 | x2 = 3.14 | 4 | 0.53 |
| Diagnosis (schizophrenia/ schizoaffective disorder) | NA | 28/3 | NA | NA | NA |
| Illness duration mean (SD), months | NA | 22.39 (12.80) | NA | NA | NA |
| Duration of prior treatment mean (SD), months | NA | 6.16 (10.10) | NA | NA | NA |
| Current use of antipsychotics (yes/no) | NA | 31/0 | NA | NA | NA |
| Prior use of antipsychotics (yes/no) | NA | 23/8 | NA | NA | NA |
| PANSS positive mean (SD) score | NA | 25.83 (14.90) | NA | NA | NA |
| PANSS negative mean (SD) score | NA | 24.10 (7.53) | NA | NA | NA |
| PANSS general mean (SD) score | NA | 40.45 (10.20) | NA | NA | NA |
| PANSS total mean (SD) score | NA | 86.82 (21.83) | NA | NA | NA |
N sample size, SCZ schizophrenia, SCZA schizoaffective disorder, PANSS Positive and Negative Syndrome scale, t (independent samples t-test), x2 (chi-square test), degrees of freedom (df), NA not applicable, SD standard deviation
aYears of education: calculated as the years of education after compulsory education (minimum compulsory education in the United Kingdom is 12 years)
bSocio-economic status: High = high, intermediate and lower grade professionals; medium = small employer, self-employed and lower technical occupations; low = sales, routine occupations, unemployed; student = student