Psychiatric Co-morbidity in Ketamine and Methamphetamine Dependence: a Retrospective Chart Review

Both ketamine and methamphetamine (MA) have become very popular and have been abused worldwide over the past two decades. However, the relationship between dependence on ketamine or MA and psychiatric comorbidities is still unclear. This study aimed to examine the frequency of co-morbid psychiatric disorders in patients dependent on ketamine or methamphetamine who were receiving treatment at three substance abuse treatment clinics (SACs) in Hong Kong. This was a retrospective chart review. The medical records of 183 patients (103 with ketamine and 80 with MA dependence) treated between January 2008 and August 2012 were retrieved. Patients’ demographic data, patterns of substance abuse and comorbid psychiatric diagnoses were recorded. The mean age of onset and duration of substance abuse were 18.1 ± 4.7 and 9.2 ± 6.2 years for ketamine and 19.9 ± 8.8 and 10.5 ± 9.8 years for MA users, respectively. Psychotic disorders were more common in MA dependent users (76.2 % vs. 28.2 %, p < 0.001), whereas mood disorders were more common in ketamine dependent users (27.2 % vs. 11.2 %, p = 0.008). Ketamine and MA dependence have a notably different profile of psychiatric co-morbidity. Compared with MA dependence, ketamine dependence is more likely to be associated with mood disorders and less likely with psychotic disorders.