Table 1. Characteristics of study participants.
| SCHIZOPHRENIA PATIENTS | HEALTHY PARTICIPANTS | ||||
| MTHFR genotype | C/C (n = 14) | C/T (n = 13) plus T/T (n = 4) | C/C (n = 13) | C/T (n = 9) plus T/T (n = 3) | P * |
| DEMOGRAPHICS | |||||
| Age at fMRI | 40±3 | 45±3 | 41±3 | 39±4 | n/s |
| Sex | 12 M, 2 F | 12 M, 5 F | 10 M, 3 F | 10 M, 2 F | n/s |
| Race | 9 European, 5 Other | 14 European, 3 Other | 12 European, 1 Other | 9 European, 3 Other | n/s |
| Length of illness (yrs) | 19±4 | 19±3 | – | – | n/s |
| Edinburgh handedness | 64±14 | 57±13 | 57±15 | 67±8 | n/s |
| CLINICAL | |||||
| PANSS positive | 15±5 | 14±4 | – | – | n/s |
| PANSS negative | 14±5 | 15±5 | – | – | n/s |
| PANSS general | 30±9 | 31±8 | – | – | n/s |
| CPZ equivalents | 435±94 | 465±78 | – | – | n/s |
| PERFORMANCE AND MOTION | |||||
| Estimated verbal IQ | 101±3 | 97±3 | 106±4 | 110±4 | healthy>patient, p = .01 |
| Antisaccade latency (ms) | |||||
| • correct trials | 300±16 | 277±14 | 276±12 | 272±14 | n/s |
| • error trials | 202±13 | 189±10 | 185±10 | 183±15 | n/s |
| Antisaccade % error | 26±6 | 32±5 | 13±3 | 18±3 | patient>healthy, p = .004 |
| Post-error slowing (ms; positive = slower)** | 16±7 | −4±7 | 13±8 | 7±8 | C/C>T, p = .08 |
| Average motion (mm) | 2.33±0.28 | 2.43±0.25 | 1.98±0.29 | 2.31±0.30 | n/s |
Statistical tests were performed using ANOVA or chi-square as appropriate, with alpha (2-tailed) = 0.05. Abbreviations: fMRI, functional magnetic resonance imaging; PANSS, positive and negative syndrome scale; CPZ, chlorpromazine.
*n/s, no significant main effects of genotype or diagnosis, or significant genotype×diagnosis interaction.
**Post-error slowing was calculated as the difference in saccadic latency between correct trials following an error and correct trials immediately prior to errors.