MedWire News: Patterns of substance use in patients with bipolar disorder are different from those in patients with schizophrenia, study results suggest.

The findings, published in the journal Psychological Medicine, may help improve the treatment of alcohol and drug problems in people with severe mental health conditions.

"The level of substance use in patients with severe mental illness is known to be high," explain Dr P Ringen, from Ullevål University Hospital in Oslo, Norway, and team.

They add that "substance use has been associated with a more severe course and outcome in both schizophrenia and bipolar disorder", but they point out that few previous studies have directly compared substance-use patterns among patients with these disorders.

To investigate further, the researchers studied 336 patients with schizophrenia or bipolar disorder from the same geographical area of Norway.

All the patients underwent clinical assessments and were interviewed about their drug-use history, habits and patterns of use.

The team found that patients with bipolar disorder had higher rates of alcohol consumption than those with schizophrenia. However, schizophrenia patients used centrally stimulating substances, such as amphetamine and cocaine, and other types of drugs more often than those with bipolar disorder.

Furthermore, schizophrenia patients used non-alcohol drugs more frequently than bipolar patients used alcohol.

"The main finding of the present study was clear differences in substance-use patterns in schizophrenia and bipolar disorder," say Dr Ringen and team.

They conclude: "This suggests a need for disease-specific treatment strategies, and indicates separate underlying disease mechanisms."