Men and women aged 50 years and older who have been diagnosed with schizophrenia are at greater risk of suicide, according to research in the February issue of Schizophrenia Research.

This was especially true for middle-age and older women diagnosed with schizophrenia.

An estimated 1 in 1,000 adults aged 65 years and older are thought to have schizophrenia, previous studies show. Some 7%-17% of older adults who commit suicide have schizophrenia, compared with 8.5% of patients in the general population. Even without schizophrenia, studies have shown that older adults have the highest rate of suicide among all age groups.

The most recent findings come from a team of researchers led by Annette Erlangsen, Ph.D., and William W. Eaton, Ph.D., Dr. Erlangsen, Dr. Eaton, and their colleagues sought to determine whether an elevated risk of suicide associated with schizophrenia exists during the second half of life and which factors might help predict that risk.

Using individual-level register data, the researchers performed a nationwide cohort study of some 2,899,411 individuals (1,382,390 men, 1,517,021 women) aged 50 and older who lived in Denmark between 1990 and 2006 (Schizophr. Res. 2012; 134;111-7). They also gathered historical information on psychiatric hospitalizations since 1970 and obtained gender-specific suicide rates using the exact number of person-days under exposure.

Indeed, there was an excess in mortality because of suicide among older adults with schizophrenia, which declined with decreasing age, when compared with the remainder of the population, reported Dr. Erlangsen of the Mental Health Centre Copenhagen and the Johns Hopkins School of Public Health, Baltimore, and Dr. Eaton of Johns Hopkins.

Since 1970, the researchers learned, 8,893 men (0.64%) and 9,165 women (0.60%) had been diagnosed with schizophrenia during a hospitalization. Also, 5,230 men and 2,911 women died by suicide, including 125 men (2.4%) and 123 women (4.2%) who had been diagnosed with schizophrenia.

Suicide rates per 100,000 person-years were significantly higher among all patients diagnosed with schizophrenia vs. those without the disorder, although the rates did decrease with age. The rates were as follows: 217.7 vs. 31.3 among men aged 50-69 years; 107.2 vs. 51.6 among men aged 70 years and older; 218.1 vs. 15.9 among women aged 50-69 years; and 68.3 vs. 20.0 among women aged 70 years and older.

These findings confirm earlier studies that show excess mortality from suicide among older men with schizophrenia and establish an increased risk among women aged 70 years and older with schizophrenia. Higher suicide rates among women might be tied to the late onset of schizophrenia. In addition, women tend to present more positive symptoms than do men – symptoms that have been linked to suicide risks.

"However, a more plausible explanation might be that men with schizophrenia died earlier in their life course," the researchers said.

Suicide rates might have declined with age as older adults with schizophrenia might have learned to adapt to the disorder.

Among other findings:

• The risk of suicide in older adults hospitalized with schizophrenia was lower than for other psychiatric inpatients. An elevated risk of suicide remained among previously hospitalized individuals vs. those with no psychiatric diagnoses. Also, 62% percent of men and 67% of women diagnosed with schizophrenia and who died by suicide had been admitted to a psychiatric hospital more than six times, "indicating a chronic disease course with several relapses," they said. The risk was elevated for both genders during the first 3 months after admission and the first 3 months after discharge.

• The risk of suicide in older adults diagnosed with mood disorders and schizophrenia was almost as high as those diagnosed only with schizophrenia. Among women with schizophrenia, coexisting personality disorders or substance abuse further elevated the risk of suicide.

• There was a 15-fold increased risk for men and a 22-fold increase for women who attempted suicide within the previous 365 days vs. those who made no recent attempt. This emphasizes the importance of suicide attempts as a risk indicator, the researchers said.

"In terms of implications, both recently discharged, history of several hospitalizations, co-existing psychiatric disorders, and suicide attempts represent well-defined high risk groups with respect to interventions," the researchers said. "Prevention of suicide in older adults should predominantly be aimed at intervening early in the suicidal process. Follow-up during medical treatment and assessment for depression seem to be successful strategies. It is possible that older adults with schizophrenia would profit from similar approaches."

The strength of this study is the complete data collection from the entire population of Denmark, the researchers said. One limitation, however, is that only subjects diagnosed during a psychiatric or somatic hospitalization were considered to have schizophrenia, which might have led to an underestimation.

The authors reported no conflicts of interest. Dr. Erlangsen received a grant from the Danish Ministry of Welfare for the study. Dr. Eaton received a grant from the National Institute of Mental Health at the National Institutes of Health.

Suicide Risk Higher Among Older Schizophrenia Patients