A new study is raising the question of whether certain cholesterol, blood pressure and diabetes drugs could help manage mental illnesses like schizophrenia.
The findings come from a study of over 142 000 Swedish patients with serious mental illnesses – including schizophrenia and bipolar disorder. The researchers found that those patients typically fared better during periods when they were taking certain medications to treat high cholesterol, high blood pressure or diabetes.
Compared with periods when they were not on those drugs, they were less likely to end up in a psychiatric hospital or attempt self-harm.
Further research needed
Specifically, the benefit was seen when patients were taking: statins, which lower cholesterol; calcium channel blockers, a group of blood pressure drugs; or the oral diabetes drug metformin, the study findings showed.
The findings do not prove that the medications had a direct effect on mental health symptoms, said lead researcher Dr Joseph Hayes, of the University College London.
But, he said, they do argue for further research.
"We believe randomised, controlled trials of these medications for severe mental illness should be the next step, and a number are underway globally," Hayes added.
An advantage is that the drugs are already approved, he noted, and researchers know a good deal about their side effects and safety.
Terry Goldberg is a professor of medical psychology at Columbia University Medical Center, in New York City. He sounded some notes of caution on the findings.
Only a correlation
There have already been small trials testing some of those medications in treating mental illness, Goldberg noted – and the results "have not been impressive".
He stressed that the new findings show only a correlation between the drugs and lower rates of hospitalisation and self-harm.
"That doesn't prove cause-and-effect," Goldberg said.
One possibility is that when patients were on those medications, they were getting better health care in general, he added.
They may also have had extra support from family to get them to medical appointments and help them stick with their prescriptions, Goldberg suggested.
Hayes agreed, and explained how his team tried to account for that: They looked at whether mentally ill patients fared any better when they had prescriptions for a diuretic (a high blood pressure drug).
More than just stability
There is existing evidence that statins, calcium channel blockers and metformin may, in theory, have mental health benefits. In contrast, there is no similar evidence for diuretics. So, Hayes explained, if medication use is simply a marker of better health care – or more stability in patients' lives – then those on diuretics should also do better.
It turned out they didn't.
"So this goes against the argument that what we observe is just related to a greater period of stability," Hayes said.
The results are based on medical records from 142,691 Swedish adults and teenagers who were treated for schizophrenia, bipolar disorder or non-affective psychosis in the years 2005 through 2016.
The researchers focused on patients' use of statins, calcium channel blockers or metformin because of the evidence those drugs might ease mental health symptoms.
Statins, for instance, are anti-inflammatory, and various psychiatric disorders are thought to involve inflammation in the central nervous system, according to Hayes. Plus, animal research has hinted that statins might have antipsychotic effects or protect brain cells from damage.
Less likely to do self-harm
Metformin, meanwhile, might help address problems in the way the brain uses glucose (sugar) in people with certain mental disorders. For their part, calcium channel blockers target so-called L-type calcium channels – which exist not only in the heart and blood vessels, but in the brain. And animal research suggests they help control emotional behaviour.
Overall, the investigators found, patients were less likely to be admitted to a psychiatric hospital during periods where they had prescriptions for any of those medications, versus other times.
They were also less likely to do self-harm, which includes suicide attempts.
The study, published online in JAMA Psychiatry, was funded by government and foundation grants.
"At this stage," Hayes said, "we are not suggesting people with these mental illnesses change their treatment."
But, he added, if they do have health conditions that warrant taking a statin, calcium channel blocker or metformin, then perhaps they should.
Goldberg agreed. "It's better to have those conditions treated than not treated," he said.
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