Suicidal behaviour and cognition: A systematic review with special focus on prefrontal deficits

Association between cognitive functioning, suicidal ideation and suicide attempts in major depressive disorder, bipolar disorder, schizophrenia and related disorders: A systematic review and meta-analysis

INTRODUCTION

Treatable mental disorders, such as psychotic, major depressive disorder (MDD), and bipolar disorder (BD), contribute to a substantial portion of suicide risk, often accompanied by neurocognitive deficits. We report the association between cognitive function and suicidal ideation/suicide attempts (SI/SA) in individuals with schizoaffective disorder, BD, and MDD.

METHODS

A systematic search was conducted on PubMed, Ovid and Scopus databases for primary studies published from inception to April 2024. Eligible articles that reported on the effect size of association between cognition and SI/SA were pooled using a random effects model.

RESULTS

A total of 41 studies were included for analysis. There was a negative association between executive functioning and SI/SA in schizoaffective disorder (SA: Corr = -0·78, 95 % CI [-1·00, 0·98]; SI: Corr = -0·06, 95 % CI [-0·85, 0·82]) and MDD (SA: Corr = -0·227, 95 % CI [-0·419, -0·017]; SI: Corr = -0·14, 95 % CI [-0·33, 0·06]). Results were mixed for BD, with a significant positive association between SA and global executive functioning (Corr = 0·08, 95 % CI [0·01, 0·15]) and negative association with emotion inhibition. Mixed results were observed for processing speed, attention, and learning and memory, transdiagnostically.

LIMITATIONS

There is heterogeneity across sample compositions and cognitive measures. We did not have detailed information on individuals with respect to demographics and comorbidities.

CONCLUSIONS

We observed a transdiagnostic association between measures of cognitive functions and aspects of suicidality. The interplay of cognitive disturbances, particularly in reward-based functioning, may underlie suicidality in individuals with mental disorders. Disturbances in impulse control, planning, and working memory may contribute to self-injurious behavior and suicide.

Factors mediating pre-existing autism diagnosis and later suicidal thoughts and behaviors: A follow-up cohort study

LAY ABSTRACT

Autistic people are more likely to experience suicidal thoughts and behaviors. The underlying relationships between potential risk factors and suicidal thoughts and behaviors in autistic individuals remain unclear. To understand this, we investigated whether specific factors in childhood/youth explain the effects of pre-existing autism spectrum disorder (ASD) diagnoses on later suicidal thoughts and behaviors in adolescence/adulthood. We assessed internalizing and externalizing problems, bullying experiences, and executive functions (including cognitive flexibility, sustained attention, and spatial working memory) at an average baseline age of 13.4 years and suicidal thoughts and behaviors at an average follow-up age of 19.2 years among 129 autistic and 121 typically developing (TD) individuals. During the follow-up period in adolescence/adulthood, autistic individuals were more likely to report suicidal thoughts than TD individuals. Being bullied partially accounted for the relationship between a pre-existing ASD diagnosis and later-reported higher suicidal thoughts. Contrary to our hypothesis, higher (instead of lower) cognitive flexibility in some autistic young people appeared to partially explain their higher rates of suicidal thoughts compared with typically developing young people. The findings imply that school bullying prevention and tailored intervention programs for autistic people, especially those with higher cognitive flexibility, are warranted to reduce their risks of experiencing suicidal thoughts.

Sex differences in the association between suicidal ideation and neurocognitive function in Chinese patients with schizophrenia

There is increasing evidence that sex differences exist in many clinical manifestations of patients with schizophrenia, including suicidal ideation (SI) and neurocognitive function. The present study was performed to explore the sex differences in the association between SI and neurocognitive function in Chinese patients with schizophrenia. A total of 1188 inpatients with schizophrenia were recruited from multicenter psychiatric hospitals. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was utilized to evaluate the neurocognitive function of all patients. The Positive and Negative Syndrome Scale (PANSS) was utilized to assess the psychopathology of patients. The Beck Scale for Suicide Ideation (BSSI) was used to assess the severity of SI. In male patients, the suicide risk score was significantly associated with PANSS negative symptoms (r = 0.167, p = 0.043), visuospatial subscale (r = - 0.261, p = 0.001), and RBANS total scores (r = - 0.172, p = 0.037). Furthermore, multivariate linear regression analysis showed that the visuospatial subscale (β = - 0.490, t = - 3.273, p = 0.001) was independently associated with the suicide risk score in male patients. In female patients, the suicide risk score was significantly correlated with PANSS positive symptoms (r = 0.249, p = 0.021), negative symptoms (r = 0.394, p < 0.001), general psychopathology (r = 0.276, p = 0.01) and PANSS total score (r = 0.365, p = 0.001). Multivariate linear regression analysis showed that PANSS negative symptoms (β = 1.849, t = 3.933, p = 0.001) were significantly associated with suicide risk scores in female patients. Our findings indicate that there are sex differences in the association between SI and neurocognitive function in patients with schizophrenia. Based on the findings of our study, gender-specific prevention and intervention strategies may make a difference in reducing SI in Chinese schizophrenia patients.

Neurological, Metabolic, and Psychopathological Correlates of Lifetime Suicidal Behaviour in Major Depressive Disorder without Current Suicide Ideation

INTRODUCTION

Suicidal behaviour (SB) has a complex aetiology. Although suicidal ideation (SI) is considered the most important risk factor for future attempts, many people who engage in SB do not report it.

METHODS

We investigated neurological, metabolic, and psychopathological correlates of lifetime SB in two independent groups of patients with major depression (sample 1: n = 230; age: 18-65 years; sample 2: n = 258; age >60 years) who did not report SI during an index episode.

RESULTS

Among adults (sample 1), SB was reported by 141 subjects (58.7%) and severe SB by 33 (15%). After controlling for interactions, four risk factors for SB emerged: male gender (OR 2.55; 95% CI: 1.06-6.12), negative self-perception (OR 1.76; 95% CI: 1.08-2.87), subthreshold hypomania (OR 4.50; 95% CI: 1.57-12.85), and sexual abuse (OR 3.09; 95% CI: 1.28-7.48). The presence of at least two of these factors had the best accuracy in predicting SB: sensitivity = 57.6% (39.2-74.5); specificity = 75.1% (68.5-82.0); PPV = 27.9% (20.9-37.2); NPV = 91.4% (87.6-94.1). In older patients (sample 2), 23 subjects (9%) reported previous suicide attempts, which were characterized by earlier onset (25 years: OR 0.95: 0.92-0.98), impaired verbal performance (verbal fluency: OR 0.95: 0.89-0.99), higher HDL cholesterol levels (OR 1.04: 1.00-1.07) and more dyskinesias (OR 2.86: 1.22-6.70).

CONCLUSION

Our findings suggest that SB is common in major depressive disorder, even when SI is not reported. In these individuals it is feasible and recommended to investigate both psychiatric and organic risk factors. The predictive power of models excluding SI is comparable to that of models including SI.

Reduced attentional control in individuals with a history of suicide attempts compared to those with suicidal ideation: Results from a systematic review and meta-analysis

BACKGROUND

Neurocognitive profiles may be especially useful to identify factors that facilitate transitioning from contemplating suicide to attempting suicide. Generally, those who attempt suicide show greater disruptions in neurocognitive ability compared to those who think about suicide but do not proceed to attempt. The goal of this systematic review and meta-analysis is to test whether this pattern is observed with attentional control.

METHODS

We systematically searched PubMed, PsychINFO, CINAHL, and Google Scholar to find pertinent studies. All included studies compared attentional functioning using neutral stimuli. Each sample featured adults with a history of suicidal ideation (SI) and no history of suicide attempts (SA) compared to those with a history of SA.

RESULTS

We identified 15 studies with 32 effect sizes (N = 931; n = 506 with SI only; n = 425 with SA). SA groups, compared to SI groups, exhibited worse accuracy yet similar reaction time, suggesting a comparatively blunted speed-accuracy tradeoff. Relative to SI, SA groups performed worse on Stroop-like and Go/NoGo tasks. SA performed better than SI on Trail Making Test B, but not A.

LIMITATIONS

There were few available studies. Most samples were small. We did not differentiate current vs. past SI or high vs. low lethality SA. Only English and Spanish language articles were included.

CONCLUSIONS

Disrupted attentional control may convey risk for transitioning to SA from SI. More work is needed to determine which components of attention are most associated with suicide risk.

DSM-5 suicidal behavior disorder: a systematic review of research on clinical utility, diagnostic boundaries, measures, pathophysiology and interventions

Background

It has been a decade since Suicidal Behavior Disorder (SBD) was introduced in Section III of the DSM-5 under "Conditions for Further Study". SBD is chiefly characterized by a self-initiated sequence of behaviors believed at the time of initiation to cause one's own death and occurring in the last 24 months.

Aims

To systematically review empirical studies on SBD to identify primary research themes and promising future research directions.

Method

A search of empirical articles on SBD published between May 2013 and March 2023 was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Results

Screening of 73 records by two independent raters yielded 14 eligible articles. The primary research themes identified from these articles included clinical utility of SBD to predict future suicide risk, association of SBD with closely related disorders, psychometric properties of SBD measures, pathophysiology of SBD, and the effectiveness of interventions for people with SBD.

Conclusion

Understanding of SBD has slowly progressed since its introduction a decade ago and has mainly been applied in research to define study groups displaying suicidal behavior. The clinical utility of SBD for predicting future suicide risk is low and more research is needed to understand measurement of the diagnosis and its distinctiveness from related disorders and other self-harming behaviors.

Suicidal ideation in Chinese adults with schizophrenia: associations with neurocognitive function and empathy

BACKGROUND

Suicidal ideation is common among people diagnosed with schizophrenia spectrum disorders and may be related to neurocognitive, social cognitive, and clinical variables. This study aimed to investigate the relationships between suicidal ideation and both neurocognitive function and empathy.

METHODS

The sample for this cross-sectional study comprised 301 schizophrenic patients aged 18-44 years. All participants were administered the Beck Scale for Suicide Ideation-Chinese Version (BSI-CV), the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), the Interpersonal Reactivity Index (IRI), and the Positive and Negative Syndrome Scale (PANSS). The demographic and clinical data of the patients were also collected.

RESULTS

In total, 82 patients reported suicidal ideation. Compared to patients without suicidal ideation, patients with suicidal ideation showed significant differences in the IRI-Personal Distress subscale, PANSS-General Psychopathology symptom scores, and suicide attempts. Moreover, there were moderating effects of neurocognitive function and empathy on the relationship between suicide attempts and suicidal ideation.

CONCLUSIONS

These results indicate that the personal distress component of empathy, general psychopathology symptoms and suicide attempts are independent risk factors for suicidal ideation in Chinese adults with schizophrenia. Moreover, neurocognitive function may also be related to suicidal ideation through a moderating relationship. In order to reduce suicidal ideation among patients with schizophrenia, early screening of empathy and neurocognitive function is essential.

Association between childhood cognitive skills & adult suicidal behavior: A systematic review and meta-analysis

BACKGROUND

It is unclear whether cognitive skill deficits during childhood carry risk for suicide attempt or mortality later in adulthood at the population level. We conducted a systematic review and meta-analysis of population-based studies examining the association between childhood cognitive skills and adult suicidal behavior, namely attempt and mortality.

METHOD

We systematically searched databases for articles then extracted study characteristics and estimates on the association between childhood cognitive skills (i.e., IQ or school performance at age ≤ 18 years) and later suicide attempt and mortality. Random-effect meta-analysis was used to quantify this association across all studies with available data.

RESULTS

Twenty-three studies met the inclusion criteria and suggest an association between lower childhood cognitive skills and increased risk of suicidal behavior. Meta-analysis of the adjusted estimates from 11 studies (N = 2,830,191) found the association to be small but statistically significant. Heterogeneity was significant but moderate, and results were unlikely to be influenced by publication bias. In subgroup analyses, associations were significant only for males. No difference in effect size was found between suicide attempt and suicide mortality.

LIMITATIONS

Cognitive skills were measured with different cognitive subtests. Heterogeneity in the age of cognitive skills assessment. Meta-regression and subgroup analyses were based on a relatively low number of studies.

CONCLUSIONS

Individuals with lower cognitive skills in childhood have a greater risk of suicidal behavior in adulthood, especially males. Although the association was small, interventions improving cognitive skills may yield large effects on suicide prevention at the population level if the association is causal.

Influencing factors of multiple adverse outcomes among schizophrenia patients using count regression models: a cross-sectional study

BACKGROUND

Schizophrenia patients have increased risks of adverse outcomes, including violent crime, aggressiveness, and suicide. However, studies of different adverse outcomes in schizophrenia patients are limited and the influencing factors for these outcomes need clarification by appropriate models. This study aimed to identify influencing factors of these adverse outcomes by examining and comparing different count regression models.

METHODS

This study included schizophrenia patients who had at least one follow-up record in the Guangdong Mental Health Center Network Medical System during 2020. Three types of adverse outcomes were included: a) aggressiveness with police dispatch or violent crime, b) aggressiveness without police dispatch, and c) self-harm or suicide attempts. The incidence density of these adverse outcomes was investigated using the Poisson, negative binomial (NB), zero-inflated Poisson (ZIP), and zero-inflated negative binomial (ZINB) models, accordingly. The best model was chosen based on goodness-of-fit tests. We further analyzed associations between the number of occurrences of adverse outcomes and sociodemographic, clinical factors with the best model.

RESULTS

A total of 130,474 schizophrenia patients were enrolled. Adverse outcomes rates were reported to be less than 1% for schizophrenia patients in 2020, in Guangdong. The NB model performed the best in terms of goodness-of-fit and interpretation when fitting for the number of occurrences of aggressiveness without police dispatch, whereas the ZINB models performed better for the other two outcomes. Age, sex, and history of adverse outcomes were influencing factors shared across these adverse outcomes. Higher education and employment were protective factors for aggressive and violent behaviors. Disease onset aged ≥ 18 years served as a significant risk factor for aggressiveness without police dispatch, and self-harm or suicide attempts. Family history of mental diseases was a risk factor for self-harm or suicide attempts individually.

CONCLUSIONS

NB and ZINB models were selected for fitting the number of occurrences of adverse outcomes among schizophrenia patients in our studies. Influencing factors for the incidence density of adverse outcomes included both those shared across different types and those individual to specific types. Therefore, comprehensive and customized tools in risk assessment and intervention might be necessary.

Inflammation biomarkers in suicide attempts and their relation to abuse, global functioning and cognition

OBJECTIVES

To explore the link between cytokines and suicide attempts and their relationship with the psychological aspects of this complex multifactorial phenomenon.

METHODS

96 participants, including 20 patients with a recent suicide attempt and diagnosis of Major Depression Disorder (MDD), 33 MDD patients with a lifetime history of suicide attempt, 23 non-attempter MDD patients, and 20 healthy controls underwent an assessment on depressive symptoms, global functioning, aggressive behaviour, presence of abuse and attention performance. Additionally, all participants had a blood extraction for IL-2, IL2-R, IL-4, IL-6, and TNF-α plasma levels analysis.

RESULTS

IL-6 levels were significantly different across groups (F(3,89)=3.690; p = 0.015), with higher concentrations in both recent (p = 0.04) and distant (p = 0.015) attempt in comparison to MDD non-attempters. IL-6 was associated with adult physical abuse (B = 2.591; p = 0.021), lower global functioning score (B = -0.512; p = 0.011), and poorer performance on attention (B = -0.897; p = 0.011).

CONCLUSIONS

Recent and distant suicidal behaviour is associated with elevated IL-6 levels, which may be influenced by stressful and traumatic experiences. Elevated concentrations of IL-6 could have a negative impact on attention, increasing suicide risk. More research is needed to clarify the role of cytokines in suicide-related features to explore novel treatments and more effective preventive interventions.

Dissecting pain processing in adolescents with Non-Suicidal Self Injury: Could suicide risk lurk among the electrodes?

Background

Although non‐suicidal self‐injury (NSSI) disorder is highly prevalent in adolescents, its relationship with pain system function and suicidality is still controversial. The present study was designed to assess the function of the nociceptive afferent pathways and the endogenous pain modulation in adolescent patients with NSSI and to longitudinally register any suicide attempt, describe its frequency and find a possible association between suicide, neurophysiological measures and psychological measures.

Methods

We enrolled 30 adolescents suffering from NSSI and 20 age‐ and gender‐matched healthy controls. Patients underwent a comprehensive psychological evaluation. Each participant underwent thermal pain thresholds of the quantitative sensory testing, laser‐evoked potential recording to study the ascending nociceptive pathway and the conditioned pain modulation testing to test the endogenous pain modulation.

Results

We found that patients with NSSI had a reduced amplitude of the N2 component of laser‐evoked potentials and an abnormal conditioned pain modulation. The amplitude of the N2 was associated with suicidal risk.

Conclusions

The deficit of the endogenous pain modulation likely depends on a saturation due to continuous pain solicitation. The strong association of a reduced amplitude of the N2 component with suicide suggests that it may serve as a possible biomarker in self‐harming adolescents.

Significance

The present study identifies the N2 component of laser‐evoked potentials as a possible neurophysiological biomarker of suicidal risk in patients with non‐suicidal self‐injury, therefore, raising the possibility for a non‐invasive test to identify subjects at higher risk of suicide among self‐harming patients.

Suicide Attempts, Neurocognitive Dysfunctions and Clinical Correlates in Middle-Aged and Elderly Chinese Schizophrenia Patients

Background: Suicide is a common and complex symptom of schizophrenia that may be related to clinical variables and neurocognitive function. This study aimed to investigate the associated correlates of suicide attempts in Chinese middle-aged and elderly inpatients with schizophrenia, including demographic and clinical characteristics and cognitive level, which has not yet been reported. Methods: A total of 426 schizophrenia inpatients were recruited for this study. Clinical symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS). Neurocognitive function was measured by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Results: The prevalence of suicide attempts in middle-aged and elderly Chinese schizophrenia patients was 13.3%. Female patients had a higher suicide rate than male patients. Patients with suicide attempts had significantly higher PANSS-positive subscores, depressive subscores, and RBANS-story recall than non-attempter patients (all p < 0.05). Multiple logistic regression showed that gender, positive subscore, depressive subscore and RBANS-story recall (OR = 1.10-2.19, p < 0.05) were independently associated with suicide attempts in middle-aged and elderly schizophrenia patients. Conclusions: Our study showed that the rate of suicide attempts in Chinese middle-aged and elderly schizophrenia patients is high. Compared to non-attempters, there are less cognitive impairments, more clinical symptoms, and more female patients in the suicide attempters.