Table 1. Participant Characteristics.
| Mean (SD) | |||
|---|---|---|---|
| Total | Diphenhydramine | Psilocybin | |
| No. | 95 | 46 | 49 |
| Demographic characteristics | |||
| Age, y | 45.78 (11.56) | 44.24 (12.15) | 47.18 (10.93) |
| Household income, median (range), $ | 100 000 (3700-4 000 000) | 110 000 (8000-800 000) | 100 000 (3700-4 000 000) |
| Sex | |||
| Female | 42 (44.2) | 21 (45.7) | 21 (42.9) |
| Male | 53 (55.8) | 25 (54.3) | 28 (57.1) |
| Race and ethnicity, No. (%)a | |||
| American Indian/Alaska Native | 1 (1.1) | 1 (2.2) | 0 |
| Asian | 3 (3.2) | 0 | 3 (6.1) |
| Black | 4 (4.2) | 1 (2.2) | 3 (6.1) |
| Hispanic | 14 (14.7) | 8 (17.4) | 6 (12.2) |
| Non-Hispanic White | 75 (78.9) | 37 (80.4) | 38 (77.6) |
| Drinking-related characteristics | |||
| % Drinking days | 74.85 (28.06) | 71.00 (29.02) | 78.47 (26.92) |
| % Heavy drinking days | 52.71 (30.58) | 47.93 (28.74) | 57.20 (31.84) |
| Drinks per day | 4.78 (2.62) | 4.33 (2.39) | 5.20 (2.78) |
| Drinks per drinking day | 7.10 (4.05) | 6.64 (3.37) | 7.52 (4.58) |
| No. of dependence criteriab | 5.25 (1.22) | 5.41 (1.20) | 5.10 (1.23) |
| Age at onset, y | 31.42 (11.42) | 30.96 (12.03) | 31.86 (10.92) |
| Years dependent | 14.20 (9.68) | 13.00 (10.31) | 15.33 (9.00) |
| Short Index of Problems (total score) | 20.98 (9.15) | 21.60 (9.61) | 20.26 (8.89) |
| WHO risk category, No. (%)c | |||
| Very high | 30 (31.6) | 12 (26.1) | 18 (36.7) |
| High | 32 (33.7) | 15 (32.6) | 17 (34.7) |
| Moderate | 21 (22.1) | 12 (26.1) | 9 (18.4) |
| Low | 12 (12.6) | 7 (15.2) | 5 (10.2) |
Abbreviation: WHO, World Health Organization.
Race and ethnicity were determined by participant self-report according to standard National Institutes of Health categories in order to assess the representativeness of the sample. Sum is greater than 100% due to multiple categories selected by 2 participants.
Defined using the Structured Clinical Interview for DSM-IV axis I disorders.40
WHO risk categories are defined as follows. Abstinence was defined as no risk (level 0), following a recent study48 evaluating the use of WHO risk levels as a treatment outcome. For men, low risk (level 1) is defined as >0 g/d to ≤40 g/d; moderate risk (level 2) as >40 g/d to ≤60 g/d; high risk (level 3) as >60 g/d to ≤100 g/d; and very high risk (level 4) as >100 g/d. For women, low risk (level 1) is defined as >0 g/d to ≤20 g/d; moderate risk (level 2) as >20 g/d to ≤40 g/d; high risk (level 3) as >40 g/d to ≤60 g/d; and very high risk (level 4) as >60 g/d. Change in WHO risk level was calculated in relation to drinking during the 12 weeks prior to screening.