WITHDRAWN: Psychiatric Symptoms in Individuals Who Use Ketamine Versus Methamphetamine

Introduction: Chronic use of both Ketamine (“K powder”) and methamphetamine (MA, “ice”) can induce psychiatric symptoms. This study aimed at exploring drug-induced psychiatric symptoms in chronic ketamine users and MA users.

Methods: We recruited chronic ketamine and methamphetamine users from two Drug Rehabilitation Centres in China from January 2012 to October 2016. We used the Positive and Negative Syndrome Scale (PANSS), Hamilton Anxiety Rating Scale (HAM-A) and Hamilton Depression Rating Scale (HDRS) to assess the psychotic symptoms, anxiety and depression in these two groups. Independent sample t-tests or Chi-square test were conducted to determine group differences. The protocol was approved by the university ethics committee (No. S163, 2011).

Results: We recruited 380 chronic ketamine users (34 were female; mean age 26.8 years, SD: 5.36; mean years of education 11·6 years, SD: 2.5) and 462 chronic methamphetamine users (28 were female; mean age 29.4 years SD 6.32, mean years of education 11.2 years, SD 2.78). 192 (50.5%) of 380 ketamine users and 347 (75.1%) of 462 methamphetamine users (c²: 54.69, p<0·0001) had psychiatric symptoms, with a mean duration of 23.5 months (SD: 24.52) for ketamine users and 15.1 months (SD: 19.43) for methamphetamine users (t: 4.01, p<0.0001). The mean age when first having psychotic symptoms was 25.4 years (SD: 5.49) in ketamine users and 28.5 years (6.32) in methamphetamine users (t: –6.05, p<0.0001). Mean scores on PANSS TOTAL were 55.3 (SD: 24.57) in ketamine users and 61.8 (29.43) in methamphetamine users (t: -3.48, p<0.0001). Mean scores for ketamine and methamphetamine use groups on positive, negative, and general subscales were 11.5 (SD: 6.07) versus 15.1 (SD: 8.22; t: -7.11, p<0.0001), 12.4 (SD: 6.60) versus 14.5 (SD: 8.63; t: –3.78, p<0.0001), and 31.2 (SD: 13.90) versus 32.2 (SD: 15.13; t: –0.97, p=0.331), respectively. Mean scores for ketamine and methamphetamine use groups on HAM-A and HDRS were 15.5 (SD: 10.08) versus 14.4 (SD: 9.00; t: 1.67, p=0.096), 14.8 (SD: 9.81) versus 13.7 (SD: 9.60; t: 1.68, p=0.094), respectively.

Conclusions: The findings suggested no statistical significant differences in symptoms of anxiety and depression between these two groups. However, chronic methamphetamine users have higher risk of suffering from psychotic symptoms and more severity of chronic drug-induced schizophrenia-like symptoms than do chronic ketamine users. These findings might provide some implications for pharmacological (glutamatergic and dopaminergic) models of schizophrenia.