Demographic and clinical characteristics of the study sample
| Characteristic | Group; mean ± SD or no. | Statistic* | p value | ||
|---|---|---|---|---|---|
| Control (n = 77) | Schizophrenia (n = 150) | BD (n = 35) | |||
| Age, yr | 31.21 ± 9.82 | 32.63 ± 9.09 | 34.23 ± 10.49 | F2,260 = 1.30 | 0.28 |
| Sex, male:females | 47:30 | 103:47 | 16:19 | χ22 = 6.69 | 0.035‡ |
| Race, Chinese:Malay:Indian:other | 65:6:4:2 | 134:6:9:1 | 32:0:3:0 | χ22 = 6.21 | 0.40 |
| Handedness, right:left | 70:7 | 138:12 | 32:3 | χ22 0.37 | 0.83 |
| Clinical measures | |||||
| Young Mania Rating Scale score | — | — | 3.14 ± 4.62 | — | — |
| Manic episodes | — | — | 2.69 ± 1.25 | — | — |
| Depressive episodes | — | — | 1.92 ± 3.33 | — | — |
| Duration of illness, yr | — | 6.59 ± 7.38 | 3.16 ± 4.42 | t183 = 2.63 | 0.010 |
| Antipsychotic dosage, CPZ equivalents | — | 199.57 ± 184.09 | 128.86 ± 148.33 | t183 = 2.11 | 0.036 |
| Mood stabilizers, lithium:valproic acid:none | — | 5:25:120 | 9:16:10 | χ22 = 39.7 | < 0.001§ |
| Hospital admissions | — | 2.43 ± 2.76 | 2.37 ± 2.20 | t183 = −2.85 | 0.90 |
| Global Assessment of Function score | — | 50.77 ± 18.01 | 67.14 ± 20.08 | t183 = 0.124 | < 0.001¶ |
| PANSS score | |||||
| Negative Symptoms | — | 10.59 ± 3.81 | 8.20 ± 2.64 | t183 = −4.74 | < 0.001¶ |
| Positive Symptoms | — | 8.95 ± 3.02 | 7.06 ± 0.34 | t183 = 3.71 | < 0.001¶ |
| Global Psychopathology | — | 20.20 ± 3.68 | 17.80 ± 1.98 | t183 = 3.52 | < 0.001¶ |
| QOL measures† | |||||
| Physical health | 72.11 ± 10.37 | 61.54 ± 15.40 | 66.39 ± 16.44 | F2,249 = 13.38 | < 0.001** |
| Psychological | 67.64 ± 11.80 | 56.45 ± 18.50 | 65.00 ± 19.42 | F2,249 = 11.71 | < 0.001†† |
| Social relationships | 69.06 ± 15.43 | 54.34 ± 20.27 | 61.67 ± 17.17 | F2,249 = 15.46 | < 0.001‡‡ |
| Environment | 69.43 ± 10.96 | 58.53 ± 16.94 | 64.73 ± 15.49 | F2,249 = 12.82 | < 0.001§§ |
BD = bipolar disorder; CPZ = chlorpromazine; PANSS = Positive and Negative Symptoms Scale; QOL = quality of life; SD = standard deviation.
↵* The Shapiro–Wilk test was run on continuous variables to ensure normality in distribution.
↵† Seven patients with schizophrenia were missing QOL variables; they were excluded from subsequent correlational analyses between white matter laterality indices and clinical measures.
↵‡ Greater proportion of men in the schizophrenia v. the BD group (p = 0.030); post hoc Tukey test.
↵§ Greater proportion of patients with BD than schizophrenia were medicated with mood stabilizers (p < 0.001); however, the proportion of patients with schizophrenia and BD taking either lithium or valproic acid did not significantly differ (p = 0.16); post hoc Tukey test.
↵¶ Poorer global functioning in life, and more severe symptoms (positive, negative and global psychopathology) in the schizophrenia v. BD group; post hoc Tukey test.
↵** Poorer physical QOL in the schizophrenia and BD groups compared with the control group; post hoc Tukey test.
↵†† Poorer psychological QOL in the schizophrenia group compared with the control and BD groups; post hoc Tukey test.
↵‡‡ Poorer social relationships in the schizophrenia v. the control group and in the BD v. the control group; post hoc Tukey test.
↵§§ Poorer environmental QOL in schizophrenia v. control group; post hoc Tukey test.