Amphetamine availability and admissions for psychosis in New South Wales, 2001-2009

Clinicians have raised concerns about the impact of amphetamines on demand for mental health services. However, evidence for this link is limited. This study explores whether changes in the availability of amphetamines in NSW in the last decade have been associated with variations in admission to mental health units for amphetamine related conditions and for psychoses more generally.

The study examined admissions from community settings to NSW acute mental health units from 2000 to 2009. Quarterly rates of hospital admission with primary or comorbid diagnoses of stimulant use disorders, stimulant-induced psychoses and non-drug-related psychoses were compared to quarterly rates of criminal incidents of amphetamine possession and use, which provide an indirect measure of the community availability of amphetamines. Analysis was confounded by increases in mental health beds over the period. Linear regression predicted admission rates on the basis of amphetamine availability, adjusting for changing mental health bed numbers.

Amphetamine availability and admissions for psychoses increased steadily from 2000 to a peak in early 2007, but have declined since. Regression models including both amphetamine availability and bed numbers predicted 34% of variation in stimulant use disorders admission rates and 50% of variation in stimulant induced psychoses admission rates. There was no significant effect of amphetamine availability on admissions for schizophrenia and other non-drug-induced psychoses after controlling for changing bed numbers.

Increased amphetamine availability appears to have been one factor increasing demand for mental health admission in NSW over the last decade. However, there appears to have been a recent downward trend in both amphetamine availability and amphetamine-related admissions. Policies which reduce the community availability of amphetamines may result in reduced admissions for amphetamine-related mental health conditions, including amphetamine-induced psychoses. Further research is needed regarding effects of amphetamine availability on admissions for schizophrenia.