Investigating Causal Relationships Between Psychiatric Traits and Intracranial Aneurysms: A Bi-directional Two-Sample Mendelian Randomization Study

Causal association between mental disorders and cerebrovascular diseases: Evidence from Mendelian randomization study

BACKGROUND AND OBJECTIVE

Observational studies have suggested that mental disorders and cerebrovascular diseases (CVDs) may be risk factors for each other, but genetic evidence of a causal relationship is still lacking. We used Mendelian randomization (MR) studies to explore the causal relationship between mental disorders and CVDs from the genetic perspective.

METHODS

To investigate the causal association between major depressive disorder (MDD), anxiety, attention deficit/hyperactivity disorder (ADHD), bipolar disorder and schizophrenia five kinds of mental disorders and CVDs using two-sample two-way MR analysis based on publicly available genome-wide association study (GWAS) data. We used as instrumental variables (IVs) single-nucleotide polymorphisms (SNPs) that were strongly associated with mental disorders and CVDs. IVW method was used as the main analysis method, and MR-IVW, MR-Egger methods, MR-PRESSO test, leave-one-out analysis and funnel plot were used for sensitivity analysis. We further conducted a meta-analysis to summarize the currently available MR analyses.

RESULTS

The results of forward MR study showed that there was a significant causal relationship between ADHD and AS (any stroke) (p(AS) = 0.001, OR (95%CI) =1.118 (1.047-1.195)), any ischemic stroke (AIS) (p(AIS) = 0.004, OR (95%CI) =1.118(1.035-1.206)) and large artery stroke (LAS) (p(LAS) = 0.026, OR (95%CI): 1.206(1.023-1.422)). No heterogeneity, pleiotropy and outliers were found in sensitivity analysis. The reverse MR study showed that IA (intracranial aneurysm) (p(IA) = 0.033, OR (95%CI) = 1.123(1.009-1.249)) and UIA (unruptured intracranial aneurysm) (p(UIA) = 0.015, OR (95%CI) =1.040(1.008-1.074)) were risk factors for schizophrenia. Sensitivity analysis showed no pleiotropy, but there was heterogeneity. After excluding outliers, MR analysis showed that IA and UIA were still risk factors for schizophrenia. Our meta-analyses found statistical significance in causal relationships between ADHD and LAS (OR (95%CI) =1.18 (1.06-1.32), p = 0.003), IA and schizophrenia (OR (95%CI) =1.05 (1.02-1.08), p = 0.002) and UIA and schizophrenia (OR (95%CI) =1.03 (1.01-1.06), p = 0.010).

CONCLUSION

The MR study and meta-analysis suggest that genetically predicted ADHD is a risk factor for LAS, and IA and UIA increase the risk of schizophrenia. The result has implications for the development of feasible prevention strategies in the future.

Genetic evidence for the causal association of neuroticism with intracranial aneurysms: A Mendelian randomization study

OBJECTIVE

The aim of this study was to assess the potential causal relationship between neuroticism and 12 neuroticism items with intracranial aneurysms (IAs) and aneurysmal subarachnoid hemorrhage (aSAH) using a two-sample Mendelian randomization (MR) approach.

METHODS

Study data were obtained from the Genome-Wide Association Study (GWAS) pooled dataset, and we extracted summary statistics for neuroticism, 12 neuroticism items, and IAs, which were categorized into ruptured and unruptured aneurysms (IA), aSAH, and unruptured IAs (uIA). Single nucleotide polymorphisms (SNPs) were used as instrumental variables (IVs) to explore the causal relationship between exposure and outcome using five Mendelian randomization methods, with Inverse variance weighted (IVW) as the primary study method. Horizontal multiple validity tests, sensitivity analyses, and inverse MR ensured the stability of the results.

RESULTS

The two-sample MR showed a genetically predictive association between neuroticism and IA [odds ratio (OR) = 1.16; 95 % confidence interval (95 % CI): 1.04-1.30; p = 0.009], aSAH (OR = 1.17; 95 % CI: 1.03-1.33; p = 0.013) and uIA (OR = 1.30; 95 % CI: 1.07-1.59; p = 0.009) were all genetically predictive of association. Ivw showed a positive association between 5 neuroticism items and IA risk, 5 neuroticism items and aSAH risk as well as no genetically predictive association between neuroticism items and uIA. Sensitivity analysis and inverse MR confirmed the robustness of the results.

CONCLUSION

Our Mendelian randomization analysis demonstrated genetic causality between neuroticism and neuroticism items with intracranial aneurysms, aneurysmal subarachnoid hemorrhage, and unruptured intracranial aneurysms, and further studies are needed to confirm these results and explore potential mechanisms of action.

Association between psychiatric disorders and intracranial aneurysms: evidence from Mendelian randomization analysis

Objective

Several studies have explored the relationship between intracranial aneurysms and psychiatric disorders; nevertheless, the causal connection remains ambiguous. This study aimed to evaluate the causal link between intracranial aneurysms and specific psychiatric disorders.

Methods

A two-sample Mendelian randomization (MR) analysis was conducted utilizing aggregated genome-wide association study (GWAS) data from the International Stroke Genetics Association for Intracranial Aneurysms (IAs), unruptured Intracranial Aneurysm (uIA), and aneurysmal Subarachnoid Hemorrhage (aSAH). Psychiatric disorder data, encompassing Schizophrenia (SCZ), Bipolar Disorder (BD), and Panic Disorder (PD), were sourced from the Psychiatric Genomics Consortium (PGC), while Cognitive Impairment (CI) data, comprising Cognitive Function (CF) and Cognitive Performance (CP), were obtained from IEU OpenGWAS publications. Causal effects were evaluated using inverse variance weighted (IVW), MR-Egger, and weighted median methods, with the robustness of findings assessed via sensitivity analyses employing diverse methodological approaches.

Results

Our MR analysis indicated no discernible causal link between intracranial aneurysm (IA) and an elevated susceptibility to psychiatric disorders. However, among individuals with genetically predisposed unruptured intracranial aneurysms (uIA), there was a modest reduction in the risk of SCZ (IVW odds ratio [OR] = 0.95, 95% confidence interval [CI] 0.92-0.98, p = 0.0002). Similarly, IAs also exhibited a moderate reduction in SCZ risk (OR = 0.92, 95% CI 0.86-0.99, p = 0.02). Nevertheless, limited evidence was found to support a causal association between intracranial aneurysms and the risk of the other three psychiatric disorders.

Conclusion

Our findings furnish compelling evidence suggesting a causal influence of intracranial aneurysms on psychiatric disorders, specifically, both IAs and uIA exhibit a negative causal association with SCZ.

Major depressive disorder and aneurysm: A genetic study of association and causality

BACKGROUND

Association between depression and aneurysm has been implicated but the specific role of depression in aneurysm remains unclear. We aimed to comprehensively characterize the relation of major depressive disorder (MDD) with aneurysm by subtype.

METHODS

Harnessing summary statistics from genome-wide association studies (Ncase/Ncontrol = 7603/317,899 for aortic aneurysm; 7321/317,899 for thoracic aortic aneurysm; 3201/317,899 for abdominal aortic aneurysm; 1788/317,899 for cerebral aneurysm; and 246,363/561,190 for major depressive disorder), we estimated the genetic correlation between MDD and each of four aneurysm subtypes via LD Score Regression and tested the causality via various estimators under the bi-directional Mendelian randomization (MR) framework.

RESULTS

Positive genetic correlation of statistical significance, ranging between 0.15 (with thoracic aortic aneurysm, P = 0.005) and 0.25 (with abdominal aortic aneurysm, P = 0.001), was consistently observed for MDD with each aneurysm subtype. In the MR analysis of MDD as an exposure, genetic liability to MDD causally increased the risk of cerebral (odds ratio: 1.71; 95 % confidence interval: 1.26-2.34) but not aortic aneurysm. Replication analysis of an independent dataset (Ncase/Ncontrol = 6242/59,418) corroborated this signal. In contrast, causal effect was not evident for any neurysm subtype on susceptibility to MDD.

LIMITATIONS

Aneurysm could have been underdiagnosed if asymptomatic, leading to an underestimated causal impact on MDD. Non-linearity of the causal effect was not tested due to the lack of individual-level data.

CONCLUSIONS

Depression and aneurysm may share common pathomechanisms. Screening depressed population and improving the clinical management for depression may benefit the primary prevention of cerebral aneurysm.

Causal association between depression and intracranial aneurysms: a bidirectional two-sample Mendelian randomization study

Background

Although observational studies have suggested a bidirectional relation between depression and intracranial aneurysms (IAs), their causal relations remain unclear. Thus we aimed to assess the causal association between depression and IAs.

Methods

We conducted a bidirectional two-sample Mendelian randomization (MR) study using summary-level data from publicly available genome-wide association studies of depression (n = 500,199), IAs (n = 79,429), unruptured intracranial aneurysm (uIA) (n = 74,004), and subarachnoid hemorrhage (SAH) (n = 77,074). MR analyses included the inverse-variance weighted (IVW) method as the primary analytic, plus weighted-median, simple mode, weighted mode, MR-Egger, and MR PRESSO.

Results

Genetically predicted depression was strongly positively related to IAs (odds ratio [OR] = 1.69, 95% confidence interval [CI] 1.19-2.39, p = 0.003), uIA (OR = 1.96, 95% CI 1.06-3.64, p = 0.032), and SAH (OR = 1.73, 95% CI 1.14-2.61, p = 0.009). Reverse MR analyses showed that while genetically predicted uIA was positively related to depression (OR = 1.02, 95% CI 1.00-1.05, p = 0.044), no causal relations were observed for either IAs or SAH for depression.

Conclusion

Our findings provide evidence of a causal effect of depression on IAs, uIA, and SAH. For the reverse MR analyses, we found a causal impact of uIA on depression, but no causal influence of either IAs or SAH for depression.

Mood swings are causally associated with intracranial aneurysm subarachnoid hemorrhage: A Mendelian randomization study

BACKGROUND

Mood swings have been observed in patients with intracranial aneurysm (IA), but it is still unknown whether mood swings can affect IA.

AIM

To explore the causal association between mood swings or experiencing mood swings and IA through a two-sample Mendelian randomization (MR) study.

METHODS

Summary-level statistics of mood swings, experiencing mood swings, IA, aneurysm-associated subarachnoid hemorrhage (aSAH), and non-ruptured IA (uIA) were collected from the genome-wide association study. Two-sample MR and various sensitivity analyses were employed to explore the causal association between mood swings or experiencing mood swings and IA, or aSAH, or uIA. The inverse-variance weighted method was used as the primary method.

RESULTS

Genetically determined mood swings (odds ratio [OR] = 5.23, 95% confidence interval (95%CI): 1.65-16.64, p = .005) and experiencing mood swings (OR = 2.50, 95%CI: 1.37-4.57, p = .003) were causally associated with an increased risk of IA. Mood swings (OR = 5.67, 95%CI: 1.40-23.04, p = .015) and experiencing mood swings were causally associated with the risk of aSAH (OR = 2.91, 95%CI: 1.47-5.75, p = .002). Neither mood swings (OR = 1.95, 95%CI: .31-12.29, p = .478) nor experiencing mood swings (OR = 1.20, 95%CI: .48-3.03, p = .693) were associated with uIA.

CONCLUSIONS

Mood swings and experiencing mood swings increased the risk of IA and aSAH incidence. These results suggest that alleviating mood swings may reduce IA rupture incidence and aSAH incidence.

Mendelian randomisation studies of Attention Deficit Hyperactivity Disorder

Background

Observational studies have found Attention Deficit Hyperactivity Disorder (ADHD) to be associated with an increased risk of adverse outcomes as well as with early risk factors; however it is not clear whether these associations reflect causal effects. Alternatives to traditional observational studies are needed to investigate causality: one such design is Mendelian randomization (MR), which uses genetic variants as instrumental variables for the exposure.

Methods

In this review we summarise findings from approximately 50 studies using MR to examine potentially causal associations with ADHD as either an exposure or outcome.

Results

To-date, few MR ADHD studies have investigated causal evidence with other neurodevelopmental, mental health and neurodegenerative conditions but those that have suggest a complex relationship with autism, some evidence of a causal effect on depression and limited evidence of a causal effect on neurodegenerative conditions. For substance use, MR studies provide evidence consistent with a causal effect of ADHD on smoking initiation, but findings for other smoking behaviours and cannabis use are less consistent. Studies of physical health suggest bidirectional causal effects with higher body mass index, with stronger effects for childhood obesity, as well as some evidence of causal effects on coronary artery disease and stroke in adults and limited evidence of causal effects on other physical health problems or sleep. Studies suggest bidirectional relationships between ADHD and socio-economic markers and provide some evidence that low birthweight may be a causal risk factor for ADHD, while bidirectional evidence has been found for some environmental factors. Finally, there is emerging evidence of bidirectional causal links between ADHD genetic liability and biological markers of human metabolism and inflammation.

Conclusions

While MR has advantages over traditional observational designs in addressing causality, we discuss limitations of current ADHD studies and future directions, including the need for larger genome-wide association studies (and using samples of different ancestries), and for triangulation with different methods.

Psychiatric traits and intracerebral hemorrhage: A Mendelian randomization study

BACKGROUND

Psychiatric traits have been associated with intracerebral hemorrhage (ICH) in observational studies, although their causal relationships remain uncertain. We used Mendelian randomization analyses to infer causality between psychiatric traits and ICH.

METHODS

We collected data from genome-wide association studies of ICH (n = 361,194) and eight psychiatric traits among Europeans, including mood swings (n = 451,619), major depressive disorder (n = 480,359), attention-deficit/hyperactivity disorder (n = 53,293), anxiety (n = 459,560), insomnia (n = 462,341), schizophrenia (n = 77,096), neuroticism (n = 374,323), and bipolar disorder (n = 51,710). We performed a series of bidirectional two-sample Mendelian randomization and related sensitivity analyses. A Bonferroni corrected threshold of p < 0.00625 (0.05/8) was considered to be significant, and p < 0.05 was considered suggestive of evidence for a potential association.

RESULTS

Mendelian randomization analyses revealed suggestive positive causality of mood swings on ICH (odds ratio = 1.006, 95% confidence interval = 1.001-1.012, p = 0.046), and the result was consistent after sensitivity analysis. However, major depressive disorder (p = 0.415), attention-deficit/hyperactivity disorder (p = 0.456), anxiety (p = 0.664), insomnia (p = 0.699), schizophrenia (p = 0.799), neuroticism (p = 0.140), and bipolar disorder (p = 0.443) are not significantly associated with the incidence of ICH. In the reverse Mendelian randomization analyses, no causal effects of ICH on mood swings (p = 0.565), major depressive disorder (p = 0.630), attention-deficit/hyperactivity disorder (p = 0.346), anxiety (p = 0.266), insomnia (p = 0.102), schizophrenia (p = 0.463), neuroticism (p = 0.261), or bipolar disorder (p = 0.985) were found.

CONCLUSION

Our study revealed that mood swings are suggestively causal of ICH and increase the risk of ICH. These results suggest the clinical significance of controlling mood swings for ICH prevention.