Table 1.

Clinical and demographic characteristics of ketamine users and healthy subjects.

	Ketamine users (N = 93)	Healthy subjects (N = 39)
Age (years)	25.56 ± 4.61	24.77 ± 4.75
Gender (male/female)	87/6	34/5
Years of education	10.91 ± 2.56	11.54 ± 1.70
Age of first ketamine use (year)	19.75 ± 5.02
Duration of ketamine use (month)a	70.78 ± 34.52
Duration of dependence (month)b	31.57 ± 18.77
Current frequency of ketamine use (days per week)c	6.12 ± 1.58
Current average doses of ketamine consumption (gram per day)	3.16 ± 3.02
Use of other psychoactive compoundsd
Never use	20 (21.51%)
Methamphetamine	27 (29.03%)
MDMA	66 (70.97%)
Codeine hydrochloride	13 (13.98%)
Cannabis	22 (23.66%)
Cocaine	1 (1.08%)
Heroin	2 (2.15%)
PANSS
Positive symptom subscale	8.01 ± 1.82
Negative symptom subscale	13.10 ± 3.74
General psychopathology subscale	24.23 ± 5.09
Total score	45.34 ± 8.70
BDI	12.69 ± 6.08
BAI	15.10 ± 8.37
Alcohol
Drink frequentlye	27 (29%)**	5 (12.8%)
Not drink frequentlyf	66 (71%)**	34 (87.2%)
Tobacco
Smoke frequentlyg	88 (94.6%)**	19 (48.7%)
Not smoke frequentlyh	5 (5.4%)**	20 (51.3%)

Data are the mean ± standard deviation.

Data about use of other psychoactive compounds, alcohol consumption and tobacco smoking are the amount of cases (percentage).

N, number of subjects included in the study; M, male; F, female; MDMA 3,4-methylenedioxymethamphetamine.

^aTotal months of ketamine use from the first time till now.

^bTotal months of ketamine use from dependent till now.

^cFrequency of ketamine use in recent one month.

^dUse of other psychoactive compounds in one’s life span, alcohol and tobacco excluded.

^eDrink no less than once a week.

^fIncluding abstinence, drinking less than once a week and never drinking.

^gSmoke no less than 3 days per week.

^hIncluding cessation, smoking less than 3 days per week and never smoking.

^**p value < 0.01.