Prenatal and Early Childhood Infections and Subsequent Risk of Obsessive-Compulsive Disorder and Tic Disorders: A Nationwide, Sibling-Controlled Study

Prenatal and early childhood infections requiring hospitalization and risk of neurodevelopmental disorders in offspring: a population-based birth cohort study in Taiwan

In utero and early childhood infections have been associated with an increased risk of neurodevelopmental disorders; however, the observed associations may be confounded by familial predispositions. This study examined the neurodevelopmental disorders attributable to maternal infections during pregnancy and early childhood infections during the first year of life, including autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), tic disorders, and mental retardation (MR). We performed population and sibling comparison analyses to account for unmeasured familial confounding factors. We conducted a register-based cohort study with 2,885,662 individuals (comprising 1,864,660 full siblings) born in Taiwan between 2001 and 2018 and followed up until 2021. We employed Cox regression analysis to assess the association between in utero and early childhood infections requiring hospitalization and the subsequent risk of neurodevelopmental disorders. In the population analyses, an offspring exposed to maternal infection had an increased risk for ASD (hazard ratio (HR) = 1.19, 95% confidence interval (CI): 1.13-1.26), ADHD (HR = 1.14, 95% CI: 1.11-1.18), and MR (HR = 1.21, 95% CI: 1.13-1.30). These associations attenuated toward null in the sibling analyses. Individuals exposed to early childhood infection had an increased risk for ASD (HR = 1.13, 95% CI: 1.10-1.16), ADHD (HR = 1.16, 95% CI: 1.15-1.18), tic disorders (HR = 1.12, 95% CI: 1.09-1.15), and MR (HR = 1.64, 95% CI: 1.60-1.69) in the population analyses; these associations were also significant for ASD (HR = 1.14, 95% CI: 1.07-1.21) and MR (HR = 1.52, 95% CI: 1.44-1.62) in the sibling analyses. The association between maternal infection during pregnancy and offspring neurodevelopmental risk is largely due to familial confounding factors. Conversely, infection in early childhood may be attributable to it being a sensitive period and may play a role in the subsequent risk of ASD and MR.

Unraveling the Boundaries, Overlaps, and Connections between Schizophrenia and Obsessive-Compulsive Disorder (OCD)

Schizophrenia (SCZ) and obsessive-compulsive disorder (OCD) typically have distinct diagnostic criteria and treatment approaches. SCZ is characterized by delusions, hallucinations, disorganized speech, and cognitive impairments, while OCD involves persistent, intrusive thoughts (obsessions) and repetitive behaviors (compulsions). The co-occurrence of these disorders increases clinical complexity and poses significant challenges for diagnosis and treatment. Epidemiological studies indicate a significant overlap, with prevalence rates of comorbid OCD in SCZ patients ranging from 12% to 25%, which is higher than in the general population. Etiological hypotheses suggest shared genetic, neurobiological, and environmental factors, with genetic studies identifying common loci and pathways, such as glutamatergic and dopaminergic systems. Neuroimaging studies reveal both overlapping and distinct neural abnormalities, indicating shared and unique neurobiological substrates. Environmental factors, like early life stressors and urbanicity, also contribute to the comorbidity. The overlapping clinical features of both disorders complicate diagnosis. Treatment approaches include combining SSRIs with antipsychotics and cognitive behavioral therapy (CBT). The complexity of SCZ and OCD comorbidity underscores the need for a dimensional, spectrum-based perspective on psychiatric disorders, alongside traditional categorical approaches, to improve diagnosis and treatment outcomes.

In search of environmental risk factors for obsessive-compulsive disorder: study protocol for the OCDTWIN project

BACKGROUND

The causes of obsessive-compulsive disorder (OCD) remain unknown. Gene-searching efforts are well underway, but the identification of environmental risk factors is at least as important and should be a priority because some of them may be amenable to prevention or early intervention strategies. Genetically informative studies, particularly those employing the discordant monozygotic (MZ) twin design, are ideally suited to study environmental risk factors. This protocol paper describes the study rationale, aims, and methods of OCDTWIN, an open cohort of MZ twin pairs who are discordant for the diagnosis of OCD.

METHODS

OCDTWIN has two broad aims. In Aim 1, we are recruiting MZ twin pairs from across Sweden, conducting thorough clinical assessments, and building a biobank of biological specimens, including blood, saliva, urine, stool, hair, nails, and multimodal brain imaging. A wealth of early life exposures (e.g., perinatal variables, health-related information, psychosocial stressors) are available through linkage with the nationwide registers and the Swedish Twin Registry. Blood spots stored in the Swedish phenylketonuria (PKU) biobank will be available to extract DNA, proteins, and metabolites, providing an invaluable source of biomaterial taken at birth. In Aim 2, we will perform within-pair comparisons of discordant MZ twins, which will allow us to isolate unique environmental risk factors that are in the causal pathway to OCD, while strictly controlling for genetic and early shared environmental influences. To date (May 2023), 43 pairs of twins (21 discordant for OCD) have been recruited.

DISCUSSION

OCDTWIN hopes to generate unique insights into environmental risk factors that are in the causal pathway to OCD, some of which have the potential of being actionable targets.

Association of Primary Immunodeficiencies in Parents With Psychiatric Disorders and Suicidal Behavior in Their Offspring

Importance

Maternal immune activation (MIA) leading to altered neurodevelopment in utero is a hypothesized risk factor for psychiatric outcomes in offspring. Primary antibody immunodeficiencies (PIDs) constitute a unique natural experiment to test the MIA hypothesis of mental disorders.

Objective

To assess the association of maternal and paternal PIDs with psychiatric disorders and suicidal behavior in offspring.

Design, Setting, and Participants

Cohort study of 4 294 169 offspring of parents with and without PIDs living in Sweden at any time between 1973 and 2013. Data were extracted from Swedish nationwide health and administrative registers and were analyzed from May 5 to September 30, 2022. All individuals with diagnoses of PIDs identified between 1973 and 2013 from the National Patient Register were included. Offspring were included if born before 2003. Parent-offspring pairs in which both parents had a history of PIDs were excluded.

Exposures

Lifetime records of parental PIDs according to the International Classification of Diseases, Eighth Revision (ICD-8); International Classification of Diseases, Ninth Revision (ICD-9); and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) diagnostic codes.

Main Outcomes and Measures

Lifetime records of 10 psychiatric disorders and suicidal behavior identified using ICD-8, ICD-9, and ICD-10 diagnostic codes, including suicide attempts and death by suicide, among offspring. Covariates included sex, birth year, parental psychopathology, suicide attempts, and autoimmune diseases. Additional analyses excluded offspring with their own PIDs and autoimmune diseases. Poisson regression models were fitted separately for mothers and fathers to estimate incidence rate ratios (IRRs) and 95% CIs for the risk of psychiatric and suicidal behavior outcomes in the offspring of PID-exposed vs PID-unexposed mothers or fathers.

Results

The cohort included 4 294 169 offspring (2 207 651 males [51.4%]) and 3 954 937 parents (1 987 972 females [50.3%]). A total of 7270 offspring (0.17%) had parents with PIDs, and 4 286 899 offspring had parents without PIDs. In fully adjusted models, offspring of mothers with PIDs had an increased risk of any psychiatric disorder, while no such risks were observed in offspring of fathers with PIDs (IRR, 1.17; 95% CI, 1.10-1.25 vs IRR, 1.03; 95% CI, 0.94-1.14; P < .001). Likewise, an increased risk of suicidal behavior was observed among offspring of mothers with PIDs but not offspring of fathers with PIDs (IRR, 1.20; 95% CI, 1.06-1.36 vs IRR, 1.10; 95% CI, 0.91-1.34; P = .01). For the offspring of mothers with PIDs, the risk of developing any psychiatric disorder was significantly higher for those with mothers with 6 of 10 individual disorders, with IRRs ranging from 1.15 (95% CI, 1.04-1.26) for anxiety and stress-related disorders and 1.15 (95% CI, 1.03-1.30) for substance use disorders to 1.71 (95% CI, 1.37-2.14) for bipolar disorders. Offspring of mothers with both PIDs and autoimmune diseases had the highest risk for any psychiatric disorder (IRR, 1.24; 95% CI, 1.11-1.38) and suicidal behavior (IRR, 1.44; 95% CI, 1.17-1.78).

Conclusions and Relevance

Findings of this cohort study suggest that maternal, but not paternal, PIDs were associated with a statistically significant increased risk of psychiatric disorders and suicidal behavior in the offspring, particularly when PIDs co-occur with autoimmune diseases. These findings align with the MIA hypothesis of mental disorders, but the precise mechanisms remain to be elucidated.