Risky behaviours such as reckless driving or sudden promiscuity, or nervous behaviours such as agitation, hand-wringing or pacing, can be signs that suicide risk may be high in depressed people, researchers report.
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Other warning signs may include doing things on impulse with little thought about the consequences. Depressed people with any of these symptoms are at least 50 percent more likely to attempt suicide, the new study found.
"Assessing these symptoms in every depressed patient we see is extremely important, and has immense therapeutical implications," study lead author Dr Dina Popovic, of the Hospital Clinic de Barcelona, in Spain, said in a news release from the European College of Neuropsychopharmacology (ECNP).
The findings were scheduled for presentation at the ECNP's annual meeting in Amsterdam.
One expert in the United States concurred with the findings.
"It has long been known that those patients with depression who also experience anxiety and/or agitation are more likely to attempt or complete suicide," said Dr Donald Malone, chair of psychiatry and psychology at the Cleveland Clinic.
"These symptoms can also be a clue that the underlying diagnosis is bipolar depression (manic depressive disorder)," he added.
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In the study, Popovic's team looked at more than 2,800 people with depression, including nearly 630 who had attempted suicide. The researchers conducted in-depth interviews with each patient, and especially looked for differences in behaviours between depressed people who had attempted suicide and those who had not.
A 'mixed episode'
Certain patterns of behaviour began to emerge, the study authors said.
"Most of these symptoms will not be spontaneously referred by the patient, [so] the clinician needs to inquire directly," Popovic said.
She and her colleagues also found that "depressive mixed states" often precede suicide attempts.
"A depressive mixed state is where a patient is depressed, but also has symptoms of 'excitation', or mania," Popovic explained. "We found this significantly more in patients who had previously attempted suicide, than those who had not.
"In fact, 40 percent of all the depressed patients who attempted suicide had a 'mixed episode' rather than just depression. All the patients who suffer from mixed depression are at much higher risk of suicide."
The researchers reported that the standard criteria for diagnosing depression spotted only 12 percent of patients with mixed depression. In contrast, using the new criteria identified 40 percent of these patients, Popovic's team said.
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"This means that the standard methods are missing a lot of patients at risk of suicide," she said.
Malone agreed that a "mixed state" can heighten odds for suicide.
"This study appropriately cautions caregivers to pay particular attention to suicide risk when treating patients with mixed states," he said.
"Bipolar patients are at higher risk of suicide in general when compared with non-bipolar depression, even when not in a mixed state," Malone said. Drug treatments for bipolar depression "also can differ significantly from those of unipolar depression," he added. "In fact, antidepressants can worsen the situation with bipolar patients."
According to Malone, all of this means that "accurate diagnosis is essential to deciding on effective treatment."
A study from the real world
Dr Patrice Reives-Bright directs the division of child and adolescent services at South Oaks Hospital in Amityville, New York. She said that the "more commonly known risk factors for suicide include hopelessness, history of previous attempts and recent loss or change in one's life."
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However, the impulsive and risky behaviours outlined in the new study can "also increase the likelihood of someone who is depressed to act on thoughts to end his or her life," Reives-Bright said.
She agreed with Malone that "identifying these symptoms of a mixed state is important when assessing mood symptoms and selecting treatment options for the patient."
Findings presented at medical meetings are typically considered preliminary until published in a peer-reviewed journal. However, according to Popovic, one strength of the new study is that "it's not a clinical trial, with ideal patients it's a big study, from the real world."
More than 800,000 people worldwide die by suicide every year, and about 20 times that number attempt suicide, according to the World Health Organisation. Suicide is one of the leading causes of death in young people.
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Image: Scared and depressed woman from iStock