Table 1.
Demographic and psychopathological characteristics of the participants
| Neuroleptic-naïve FE patients (n = 29) | Healthy controls (n = 33) | t, U, χ2 | p | |
|---|---|---|---|---|
| Age, years1 | 22.0 ± 4.0 | 23.2 ± 2.8 | t = 1.38 | n.s. |
| Age range, years | 18–32 | 18–31 | ||
| Cigarettes smoked per day1 | 17.4 ± 9.9 | 15.3 ± 5.0 | U = 777.5 | n.s. |
| Vocabulary test (MWT)1,2 | 23.1 ± 5.8 | 28.0 ± 4.2 | U = 191.0 | <0.01 |
| Years of education1,2 | 9.5 ± 1.3 | 12.7 ± 1.5 | U = 120.5 | <0.0012 |
| PANSS positive symptoms3 | 17.1 ± 5.3 | |||
| PANSS negative symptoms3 | 14.5 ± 4.5 | |||
| PANSS general psychopathology3 | 35.5 ± 7.1 | |||
| Females1 | 5 (17.2) | 9 (27.3) | χ2 = 0.89 | n.s. |
| Nonsmokers | 5 (17.2) | 3 (9) | χ2 = 0.91 | n.s. |
| Secondary school level of education1,2 | 25 (86.2) | 8 (24.2) | χ2= 25.8 | <0.00001 |
Data presented as means ± SD, where indicated; parentheses contain percentages. MWT = Mehrfachwahl-Wortschatz Test; PANSS = Positive and Negative Syndrome Scale.
Controls and patients were matched for age, gender, and nicotine consumption, as nicotine has been shown to influence cognitive performance [22]. However, the groups differed concerning MWT points (n = 26 patients; n = 29 healthy controls), years of education and level of education. The finding of a significant difference in verbal IQ (MWT) between the 2 groups is in line with Jazbec et al. [18] and Birkett et al. [23]. Moreover, several studies have shown that individuals who will suffer from schizophrenia in the future can undergo deterioration in IQ during early adulthood [24, 25] and that children who develop schizophrenia in adulthood are half as likely as controls to proceed to high school [26].
According to the number of years of education, participants were classified into 2 levels: (1) secondary school level (8–11 years of scholarly education excluding apprenticeship); (2) a higher school certificate (12–13 years of scholarly education). The level of education and MWT depended on each other as participants with a secondary school level had a significantly lower MWT score than the ones with a higher school certificate (U = 152.5; p < 0.001). The level of education was thus taken as a covariate in the statistical analyses.