Table 2.
Clinical characteristics of participants before and after dose reduction of antipsychotic medication
| Variable | Baseline PET Visit Mean (S.D.) or % |
Follow-up PET Visit Mean (S.D.) or % |
P-valuea |
|---|---|---|---|
| Negative symptom severity | |||
| Negative symptoms total | 15.1 (5.1) | 14.7 (5.1) | 0.06 |
| Social amotivation | 8.0 (2.7) | 7.8 (2.7) | 0.03 |
| Diminished Expression | 9.4 (3.3) | 9.3 (3.2) | 0.17 |
| Other symptoms | |||
| Positive symptoms | 8.1 (2.6) | 8.0 (2.9) | 0.42 |
| Disorganized symptoms | 7.3 (2.4) | 7.2 (2.4) | 0.23 |
| Excitement symptoms | 4.8 (1.3) | 4.7 (1.1) | 0.32 |
| Depression symptoms | 4.4 (1.7) | 4.3 (1.5) | 0.76 |
| Extrapyramidal symptoms | |||
| SAS total | 3.1 (2.5) | 1.8 (1.8) | <0.001 |
| BAS global | 0.7 (1.5) | 0.2 (0.8) | 0.005 |
| Antipsychotic dose (mg/day) | |||
| Olanzapine equivalentsb | 18.4 (8.0) | 12.0 (5.0) | <0.001 |
| Dopamine D2/3 receptor occupancy (%) | |||
| Caudate | 72.9 (8.0) | 65.2 (13.7) | <0.001 |
| Putamen | 69.8 (11.3) | 63.1 (12.9) | <0.001 |
| Ventral striatum | 72.3 (11.3) | 66.7 (13.9) | 0.002 |
| Whole striatum | 71.7 (11.0) | 65.0 (13.0) | <0.001 |
Abbreviations: BAS: Barnes Rating Scale for Drug-Induced Akathisia; PANSS: Positive and Negative Syndrome Scale; SAS: Simpson-Angus Scale.
Based on paired-samples t-tests for individuals with both baseline and follow-up PET data (N=38).
The dose of risperidone was converted to an olanzapine equivalent dosage, calculated using consensus-based antipsychotic dose equivalents based on Gardner et al. (20mg olanzapine = 6mg risperidone) (Gardner et al. 2010). The mean dose of olanzapine was 20.4 mg/day at baseline and 13.2 mg/day at follow-up (change: p<0.001), and the mean dose of risperidone was 4.5 mg/day at baseline and 2.9 mg/day at follow-up (change: p<0.001).