Cognitive function linked to suicidality in schizophrenia

By Mark Cowen

Patients with schizophrenia who have contemplated suicide or made one suicide attempt have better cognitive functioning than those who have not, research shows.

However, schizophrenia patients who have made multiple suicide attempts do not perform any better in neurocognitive tests than those who have neither contemplated nor attempted suicide.

Therefore, "a more specific focus on multiple attempters and the potentially noncognitive factors influencing suicidality in this group in future studies is warranted," say Gary Donohoe and team from Trinity College Dublin in Ireland.

The findings come from a study of suicidality among patients with schizophrenia or schizoaffective disorder who were categorized as nonattempters with no ideation (n=172), nonattempters with a history of ideation (n=62), those who made a single attempt (n=48), and those who made multiple attempts (n=27).

All of the participants completed a neuropsychologic test battery to assess general cognitive ability (IQ), episodic and working memory, and attentional control.

The researchers found that patients with a history of suicidal ideation and those who had made one suicide attempt had a higher full scale IQ than nonattempters with no ideation and multiple attempters, at 93.06 and 96.70 versus 88.37 and 88.00, respectively.

The former two groups also had a higher verbal IQ (93.19 and 99.29 vs 91.53 and 91.65, respectively) and performance IQ (93.93 and 95.14 vs 89.37 and 87.15) than the latter two groups.

In addition, patients with suicidal ideation and those who had made one suicide attempt had better episodic memory, as assessed using the logical memory 1 and 2 subtests from the Wechsler Memory Scale third edition and the Paired Associate Learned subtest from the Cambridge Automated Test Battery (CANTAB), compared with the other two groups.

Working memory, as assessed using the Wechsler Memory Scale third edition Letter-Number Sequencing task and the CANTAB Spatial Working Memory subtest, was also better in patients with suicidal ideation and those who had made one suicide attempt than in the other two groups.

"Our results demonstrated significant differences in neurocognitive function between those that had expressed suicidal ideation and/or made a single suicide attempt and those that had neither contemplated nor attempted suicide," summarize Donohoe and colleagues.

They add: "Future studies will benefit from the inclusion of both insight and lethality of suicidal behavior as a potential mediating variable between cognitive function and suicide risk in schizophrenia."

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