Selective mutism and the risk of mental and neurodevelopmental disorders among siblings.

The siblings of children with mental disorders are more likely to experience mental health issues themselves, but there has been a lack of sibling studies on selective mutism (SM). The aim of this population-based study was to use national registers to examine associations between children with SM and diagnoses of various mental disorder in their siblings. All singleton children born in Finland from 1987 to 2009, and diagnosed with SM from 1998 to 2012, were identified from national health registers and matched with four controls by age and sex. Their biological siblings and parents were identified using national registries and the diagnostic information on the siblings of the subjects and controls was obtained. The final analyses comprised 658 children with SM and their 1661 siblings and 2092 controls with 4120 siblings. The analyses were conducted using generalized estimating equations. Mental disorders were more common among the siblings of the children with SM than among the siblings of the controls. The strongest associations were observed for childhood emotional disorders and autism spectrum disorders after the data were adjusted for covariates and comorbid diagnoses among SM subjects. The final model showed associations between SM and a wide range of disorders in siblings, with strongest associations with disorders that usually have their onset during childhood. Our finding showed that SM clustered with other mental disorders in siblings and this requires further research, especially the association between SM and autism spectrum disorders. Strong associations with childhood onset disorders may indicate shared etiologies.

Risk for Premature Mortality and Intentional Self-harm in Autism Spectrum Disorders.

To examine the risk for premature mortality and intentional self-harm in autism spectrum disorders (ASD). Based on a national birth cohort. Children born in 1987-2005, diagnosed with ASD by 2007 (n = 4695) were matched with four non-ASD subjects (n = 18,450) and followed until 2015 for mortality and intentional self-harm. The risk among ASD subjects was elevated only for natural cause of death. The risk for intentional self-harm was increased in the unadjusted analyses, but decreased to non-significant after adjusting for comorbid psychiatric disorders. ASD subjects are at increased risk for premature mortality due to natural causes of death. While ASD subjects die of suicide and present with more self-harm, the association is explained by comorbid psychiatric disorders.

Increased Risk of ADHD at Short and Long Interpregnancy Intervals in a National Birth Cohort.

BACKGROUND: Short or long interpregnancy interval (IPI) may adversely impact conditions for foetal development. Whether attention deficit hyperactivity disorder (ADHD) is related to IPI has been largely unexplored. OBJECTIVES: To examine the association between IPI and ADHD in a large, population-based Finnish study. METHODS: All children born in Finland between 1991 and 2005 and diagnosed with ADHD (ICD-9 314x or ICD-10 F90.x) from 1995 to 2011 were identified using data from linked national registers. Each subject with ADHD was matched to 4 controls based on sex, date of birth, and place of birth. A total of 9564 subjects with ADHD and 34,479 matched controls were included in analyses. IPI was calculated as the time interval between sibling birth dates minus the gestational age of the second sibling. The association between IPI and ADHD was determined using conditional logistic regression and adjusted for potential confounders. RESULTS: Relative to births with an IPI of 24 to 59 months, those with the shortest IPI (<6 months) had an increased risk of ADHD (odds ratio [OR] 1.30, 95% confidence interval (CI) 1.12, 1.51) and the ORs for the longer IPI births (60-119 months and ≥120 months) were 1.12 (95% CI 1.02, 1.24) and 1.25 (95% CI 1.08, 1.45), respectively. The association of longer IPI with ADHD was attenuated by adjustment for maternal age at the preceding birth, and comorbid autism spectrum disorders did not explain the associations with ADHD. CONCLUSIONS: The risk of ADHD is higher among children born following short or long IPIs although further studies are needed to explain this association.

Suicidality among child and adolescent psychiatric inpatients: time trend study comparing 2000 and 2011.

Child and adolescent inpatient treatment has faced major changes since the year 2000, including shorter inpatient stays and a greater use of psychotropic drugs. This study explored changes and correlates of suicidal threats and suicide acts among inpatients, by comparing Finnish cross-sectional surveys from 2000 to 2011. A questionnaire that explored the background, diagnosis and treatment characteristics of inpatients was sent to all child and psychiatric wards in Finland. The data collection was carried out on specified days in 2000 and 2011. We received comprehensive data on 504 patients from 64/69 (93%) wards in 2000 and on 412 patients from 75/79 (95%) wards in 2011. The Spectrum of Suicidal Behaviour Scale was used to explore suicidality. The prevalence of suicidality did not change in this nationwide study: suicidal threat rates were 38% in 2000 and 37% in 2011, and suicide attempts in both years were 11%. The prevalence of suicidal acts was higher among girls and teenagers, while low general functioning, defined as Children's Global Assessment Scale scores of under 30, was associated with both suicidal threats and acts. Violent acts were associated with both suicidal threats and acts in 2000, but not in 2011. Despite changes in treatment practices and shorter inpatient stays, the prevalence of suicidality in child and adolescent inpatient treatment remained unchanged in Finland in 2000 and 2011.

Attention-deficit/hyperactivity disorder and risk for psychiatric and neurodevelopmental disorders in siblings.

BACKGROUND: Probands with attention-deficit/hyperactivity disorder (ADHD) are at increased risk for several psychiatric and neurodevelopmental disorders. The risk of these disorders among the siblings of probands has not been thoroughly assessed in a population-based cohort. METHODS: Every child born in Finland in 1991-2005 and diagnosed with ADHD in 1995-2011 were identified from national registers. Each case was matched with four controls on sex, place, and date of birth. The full siblings of the cases and controls were born in 1981-2007 and diagnosed in 1981-2013. In total, 7369 cases with 12 565 siblings and 23 181 controls with 42 753 siblings were included in the analyses conducted using generalized estimating equations. RESULTS: 44.2% of the cases and 22.2% of the controls had at least one sibling diagnosed with any psychiatric or neurodevelopmental disorder (risk ratio, RR = 2.1; 95% CI 2.0-2.2). The strongest associations were demonstrated for childhood-onset disorders including ADHD (RR = 5.7; 95% CI 5.1-6.3), conduct and oppositional disorders (RR = 4.0; 95% CI 3.5-4.5), autism spectrum disorders (RR = 3.9; 95% CI 3.3-4.6), other emotional and social interaction disorders (RR = 2.7; 95% CI 2.4-3.1), learning and coordination disorders (RR = 2.6; 95% CI 2.4-2.8), and intellectual disability (RR = 2.4; 95% CI 2.0-2.8). Also, bipolar disorder, unipolar mood disorders, schizophrenia spectrum disorders, other neurotic and personality disorders, substance abuse disorders, and anxiety disorders occurred at increased frequency among the siblings of cases. CONCLUSIONS: The results offer potential utility for early identification of neurodevelopmental and psychiatric disorders in at-risk siblings of ADHD probands and also argue for more studies on common etiologies.

Temporal changes in the incidence of treated psychiatric and neurodevelopmental disorders during adolescence: an analysis of two national Finnish birth cohorts.

BACKGROUND: Comprehensive overviews of the temporal changes in treated psychiatric and neurodevelopmental disorders during adolescence are scarce. We reviewed data from two national cohorts, 10 years apart, to establish the change in use of specialised services for psychiatric and neurodevelopmental diagnoses in Finland. METHODS: We compared the nationwide register-based incidence of psychiatric and neurodevelopmental diagnoses between the 12th birthday and 18th birthday of adolescents born in Finland in 1987 and 1997. Adolescents who emigrated or died before their 12th birthday and those with missing covariate data were excluded, as were those who, when aged 11 years, had lived in a municipality belonging to a hospital district with obviously incomplete data reports during any follow-up years in our study. Our primary outcomes were time to incident specialised service use for any psychiatric or neurodevelopmental disorder and for 17 specific diagnostic classes. We also investigated whether adolescents who died by suicide had accessed specialised services before their deaths. FINDINGS: The cumulative incidence of psychiatric or neurodevelopmental disorders increased from 9·8 in the 1987 cohort to 14·9 in the 1997 cohort (difference 5·2 percentage points [95% CI 4·8-5·5]) among girls, and from 6·2 in the 1987 cohort to 8·8 in the 1997 (2·6 percentage points [2·4-2·9]) among boys. The hazard ratio for the overall relative increase in neurodevelopment and psychiatric disorders in the 1997 cohort compared with the 1987 cohort was 1·6 (95% CI 1·5-1·8) among girls and 1·5 (1·4-1·6) among boys. Of the studied diagnostic classes, we noted significant (ie, p<0·001) relative increases for ten of 17 diagnoses among girls and 11 among boys. Of the adolescents who died by suicide before age 18, only five of 16 in the 1987 cohort and two of 12 in the 1997 cohort had used specialised services in the 6 months before their death. INTERPRETATION: The large absolute rise in service use for psychiatric or neurodevelopmental disorders points to the need to deliver effective treatment to a rapidly increased patient population, whereas the relative increase in specific diagnoses should inform clinical practice. Despite increasing service use, identification of adolescents at risk of suicide remains a major public health priority. FUNDING: Academy of Finland, Brain and Behavior Research Foundation, Finnish Medical Foundation.

Risk of Psychiatric and Neurodevelopmental Disorders Among Siblings of Probands With Autism Spectrum Disorders.

IMPORTANCE: Previous research has focused on examining the familial clustering of schizophrenia, bipolar disorder, and autism spectrum disorders (ASD). Little is known about the clustering of other psychiatric and neurodevelopmental disorders among siblings of persons with ASD. OBJECTIVE: To examine the risk for psychiatric and neurodevelopmental disorders among full siblings of probands with ASD. DESIGN, SETTING, AND PARTICIPANTS: The Finnish Prenatal Study of Autism and Autism Spectrum Disorders used a population-based cohort that included children born from January 1, 1987, to December 31, 2005, who received a diagnosis of ASD by December 31, 2007. Each case was individually matched to 4 control participants by sex and date and place of birth. The siblings of the cases and controls were born from January 1, 1977, to December 31, 2005, and received a diagnosis from January 1, 1987, to December 31, 2009. This nested case-control study included 3578 cases with ASD with 6022 full siblings and 11 775 controls with 22 127 siblings from Finnish national registers. Data were analyzed from March 6, 2014, to February 12, 2016. MAIN OUTCOMES AND MEASURES: The adjusted risk ratio (RR) for psychiatric and neurodevelopmental disorders among siblings of probands with ASD vs siblings of matched controls. Additional analyses were conducted separately for ASD subgroups, including childhood autism, Asperger syndrome, and pervasive developmental disorders not otherwise specified. Analyses were further stratified by sex and intellectual disability among the probands. RESULTS: Among the 3578 cases with ASD (2841 boys [79.4%]) and 11 775 controls (9345 boys [79.4%]), 1319 cases (36.9%) and 2052 controls (17.4%) had at least 1 sibling diagnosed with any psychiatric or neurodevelopmental disorder (adjusted RR, 2.5; 95% CI, 2.3-2.6). The largest associations were observed for childhood-onset disorders (1061 cases [29.7%] vs 1362 controls [11.6%]; adjusted RR, 3.0; 95% CI, 2.8-3.3), including ASD (374 cases [10.5%] vs 125 controls [1.1%]; adjusted RR, 11.8; 95% CI, 9.4-14.7), tic disorders (28 cases [0.8%] vs 24 controls [0.2%]; adjusted RR, 4.3; 95% CI, 2.3-8.2), attention-deficit/hyperactivity disorder (189 cases [5.3%] vs 180 controls [1.5%]; adjusted RR, 3.7; 95% CI, 2.9-4.7), learning and coordination disorders (563 cases [15.7%] vs 697 controls [5.9%]; adjusted RR, 3.2; 95% CI, 2.8-3.6), intellectual disability (104 cases [2.9%] vs 137 controls [1.2%]; adjusted RR, 3.1; 95% CI, 2.3-4.2), conduct and oppositional disorders (180 cases [5.0%] vs 221 controls [1.9%]; adjusted RR, 2.8; 95% CI, 2.2-3.5), and emotional disorders with onset specific to childhood (126 cases [3.5%] vs 157 controls [1.3%]; adjusted RR, 2.6; 95% CI, 1.9-3.4). Autism spectrum disorders were also associated with schizophrenia spectrum disorders, affective disorders, anxiety disorders, and other neurotic and personality disorders among siblings. CONCLUSIONS AND RELEVANCE: Psychiatric and neurodevelopmental disorders cluster among siblings of probands with ASD. For etiologic research, these findings provide further evidence that several psychiatric and neurodevelopmental disorders have common risk factors.

Parental and comorbid epilepsy in persons with bipolar disorder.

BACKGROUND: Population-based studies have demonstrated an overrepresentation of bipolar disorder (BPD) in individuals with epilepsy. However, few studies have examined the reverse association, i.e. comorbid epilepsy in individuals selected based on BPD diagnosis. No previous population-based study having examined the co-occurrence of BPD and epilepsy has adjusted for parental psychopathology. Such an adjustment is motivated by population-based studies reporting an overrepresentation of various types of parental psychiatric disorders in both BPD and epilepsy. Furthermore, an association between epilepsy in first-degree relatives and BPD has previously only been examined and demonstrated in a small clinical sample. The objective of this study is to examine the associations between parental and comorbid epilepsy and BPD, adjusting for parental psychopathology. METHODS: This nested case-control study identified 1861 cases with BPD, age up to 25 years, 3643 matched controls, and their parents from Finnish national registers. Conditional logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) and two-sided significance limits of p<0.05. RESULTS: BPD was associated with comorbid epilepsy (adjusted OR 2.53, 95% CI: 1.73-3.70) but not with parental epilepsy. Epilepsy was found in 3.33% of cases versus 1.29% of controls, 2.69% of cases' parents versus 2.53% of controls' parents. LIMITATIONS: The diagnoses were register-based, not based on standardized procedures with direct ascertainment. CONCLUSIONS: An association between BPD and comorbid epilepsy persists even after adjusting for parental psychopathology. Lack of familial clustering of BPD and epilepsy would suggest that the elevated co-occurrence of these disorders is influenced by non-genetic factors.