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Schizophrenia could cause patients to forget their medication

August 12, 2003

Patients with schizophrenia must take medication regularly to reduce their risk of relapse. But the disease impairs memory, according to an article published in BMC Psychiatry, meaning these patients may have difficulty in remembering to take their tablets.

Habitual tasks, like taking medicine every few hours, rely on "prospective memory". This type of memory, which appears to be impaired by schizophrenia, enables you to remember that you have to do something in the future, without being prompted.

Brita Elvev'åg, from the Clinical Brain Disorders Branch of the National Institute of Mental Health and her colleagues who carried out the research, wrote: "To our knowledge this is the first study to show that schizophrenia is associated with an overall impairment in habitual prospective memory performance".

The authors hypothesised that patients with schizophrenia would have problems with tasks requiring prospective memory. They might mistake remembering they have to do something with remembering they've actually done it. Their hypothesis stemmed from the theory that people with schizophrenia confuse real and imagined events.

To test their hypothesis the researchers, based at NIMH and the University of Warwick, compared the prospective memory of people with and without the disease. In each test participants manoeuvred a ball around an obstacle course for 90 seconds. They were asked to turn over a counter when they were at least 25 seconds into the test. The time delay ensured that prospective memory had to be used. Participants with schizophrenia were more likely to forget to turn over the counter.

At the end of the test the participants were asked if they had remembered to turn over the counter. Approximately a third of the time participants with schizophrenia reported they had done so when they had not.

Elvev'åg and colleagues wrote: "This would seem a worryingly high probability for such an apparently simple task that posed few problems for control participants. [] Our result suggests that patients' self-reports of having completed a habitual prospective memory task, for example taking medication, are likely to be particularly unreliable".

Schizophrenia affects one in every hundred people at some point during their lives. While there is no cure, it is treatable with antipsychotic drugs. About 80 percent of those patients who stop taking their medications after an acute episode of schizophrenia will have a relapse within a year.

BioMed Central Limited