Intellectual Functioning in Offspring of Parents with Bipolar Disorder: A Review of the Literature

The Risk for Schizophrenia-Bipolar Spectrum: Does the Apple Fall Close to the Tree? A Narrative Review

Schizophrenia (SCZ) and bipolar disorder (BD) are severe psychiatric disorders that share clinical features and several risk genes. Important information about their genetic underpinnings arises from intermediate phenotypes (IPs), quantifiable biological traits that are more prevalent in unaffected relatives (RELs) of patients compared to the general population and co-segregate with the disorders. Within IPs, neuropsychological functions and neuroimaging measures have the potential to provide useful insight into the pathophysiology of SCZ and BD. In this context, the present narrative review provides a comprehensive overview of the available evidence on deficits in neuropsychological functions and neuroimaging alterations in unaffected relatives of SCZ (SCZ-RELs) and BD (BD-RELs). Overall, deficits in cognitive functions including intelligence, memory, attention, executive functions, and social cognition could be considered IPs for SCZ. Although the picture for cognitive alterations in BD-RELs is less defined, BD-RELs seem to present worse performances compared to controls in executive functioning, including adaptable thinking, planning, self-monitoring, self-control, and working memory. Among neuroimaging markers, SCZ-RELs appear to be characterized by structural and functional alterations in the cortico-striatal-thalamic network, while BD risk seems to be associated with abnormalities in the prefrontal, temporal, thalamic, and limbic regions. In conclusion, SCZ-RELs and BD-RELs present a pattern of cognitive and neuroimaging alterations that lie between patients and healthy individuals. Similar abnormalities in SCZ-RELs and BD-RELs may be the phenotypic expression of the shared genetic mechanisms underlying both disorders, while the specificities in neuropsychological and neuroimaging profiles may be associated with the differential symptom expression in the two disorders.

Neurocognitive Development in Children at Familial High Risk of Schizophrenia or Bipolar Disorder

IMPORTANCE

Neurocognitive impairments exist in children at familial high risk (FHR) of schizophrenia and bipolar disorder. Studies on preadolescent developmental courses of neurocognition are important to describe shared and distinct neurodevelopmental pathways in these groups.

OBJECTIVE

To assess the development in specific neurocognitive functions from age 7 to 11 years in children at FHR of schizophrenia or bipolar disorder compared with children in a population-based control (PBC) group.

DESIGN, SETTING, AND PARTICIPANTS

The Danish High Risk and Resilience Study is a prospective, longitudinal, cohort study that collected data from January 1, 2013, to January 31, 2016 (phase 1), and from March 1, 2017, to June 30, 2020 (phase 2). Data were collected at 2 university hospitals in Denmark, and participants included 520 children at FHR of schizophrenia or bipolar disorder along with a PBC group matched with the group of children at FHR of schizophrenia by age, sex, and municipality.

EXPOSURES

Parental schizophrenia, bipolar disorder, or neither.

MAIN OUTCOMES AND MEASURES

Neurocognitive functioning was assessed with validated tests of intelligence, processing speed, attention, memory, verbal fluency, and executive functioning. Multilevel mixed-effects linear regression models with maximum likelihood estimation were used to estimate neurocognitive development from age 7 to 11 years.

RESULTS

At 4-year follow-up, a total of 451 children (mean [SD] age; 11.9 [0.2] years; 208 girls [46.1%]) underwent neurocognitive testing. There were a total of 170 children at FHR of schizophrenia (mean [SD] age, 12.0 [0.3]; 81 girls [47.7%]), 103 children at FHR of bipolar disorder (mean [SD] age, 11.9 [0.2] years; 45 girls [43.7%]), and 178 children in the PBC group (mean [SD] age, 11.9 [0.2] years; 82 girls [46.1%]). At either age 7 or 11 years or at both assessments, 520 children participated in the neurocognitive assessment and were therefore included in the analyses. When correcting for multiple comparisons, no statistically significant time × group interactions were observed across the 3 groups. Compared with the PBC group at 4-year follow-up, children at FHR of schizophrenia showed significant neurocognitive impairment in 7 of 24 neurocognitive measures (29.2%; Cohen d range, 0.29-0.37). Compared with children at FHR of bipolar disorder, children at FHR of schizophrenia had significant neurocognitive impairment in 5 of 24 measures (20.8%; Cohen d range, 0.29-0.38). Children at FHR of bipolar disorder and those in the PBC group did not differ significantly.

CONCLUSIONS AND RELEVANCE

In this cohort study, findings suggest that neurocognitive maturation was comparable across groups of children at FHR of schizophrenia or bipolar disorder compared with PBCs from age 7 to 11 years. Compared with the PBC group, children at FHR of schizophrenia demonstrated widespread, stable, neurocognitive impairments during this period, whereas children at FHR of bipolar disorder showed no neurocognitive impairments, which may indicate distinct neurodevelopmental pathways in children at FHR of schizophrenia and bipolar disorder.

Executive functions in 7-year-old children of parents with schizophrenia or bipolar disorder compared with controls: The Danish High Risk and Resilience Study-VIA 7, a population-based cohort study

Cognitive impairments are strongly associated with schizophrenia (SZ) and bipolar disorder (BP) with executive functions (EF) impairments as a likely key feature. Studies of everyday behavior rated EF in young children at familial high risk of SZ (FHR-SZ) are scarce and, to our knowledge, non-existent in young children at familial high risk of BP (FHR-BP). We aimed to compare everyday behavior-rated EF of FHR-SZ, FHR-BP, and control children. A nationwide population-based cohort of 522 7-year-old children with parents diagnosed with either SZ (N = 202) or BP (N = 120) and matched controls (N = 200) were recruited using the Danish national registries. The children's EF were assessed with the Behavior Rating Inventory of Executive Functions questionnaire rated by primary caregivers and teachers. According to primary caregiver assessments, FHR-SZ children displayed widespread EF impairments and had an odds ratio of 3.7 (2.0-6.9) of having clinically significant global EF impairments compared to controls. FHR-BP children were most severely impaired regarding EF related to emotional control and had an odds ratio of 2.5 (1.2-5.1) of clinically significant global EF impairments compared to controls. Teacher assessments were overall comparable to primary caregiver assessments but teachers rated more difficulties in the FHR-SZ group than primary caregivers. Already at age 7, children with a parental history of SZ or BP displayed significant impairments of EF in everyday-life situations. FHR-SZ children displayed widespread significant impairments of EF, whereas FHR-BP children were most severely impaired on emotional control. Clinicians should be aware of potential EF impairments in FHR children.

Cognitive correlates of impulsive aggression in youth with pediatric bipolar disorder and bipolar offspring

BACKGROUND

Youth with bipolar disorder (BD) and offspring of individuals with BD (BD-OFF) are characterized by higher levels of impulsive and overt aggression. The cognitive basis underlying these aggressive behaviors are not clarified in this population. The aim of this study was to investigate the relationship between cognitive alterations and aggressive behavior in youth with BD and BD-OFF.

METHODS

Forty-two youth with BD, 17 BD-OFF and 57 healthy controls (HCs) were administered the Modified Overt Aggression Scale (MOAS), the Cambridge Neuropsychological Test Automated Battery (CANTAB), the Young Mania Rating Scale (YMRS) and the Children's Depression Rating Scale (CDRS). Multiple linear regression analyses were performed in the three groups separately. In each group, tests scores from the CANTAB were predictors. MOAS subscale scores and MOAS total scores were dependent variables. Results are corrected for age, IQ and mood state.

RESULTS

Both youth with BD and BD-OFF showed positive correlations between impairment in executive functions and levels of verbal aggression. In youth with BD, altered processing of either positive and negative stimuli positively correlated with MOAS total scores, whereas in BD-OFF, such relationship was negative.

CONCLUSIONS

Impulsive aggressive behaviors in youth with BD arise from a combination of altered affective processing and executive dysfunction. The negative relationship between affective processing and aggression in BD-OFF suggested the presence of possible mechanisms of resilience in this population.

Mother-to-Infant Bonding in Women With a Bipolar Spectrum Disorder

Purpose: Offspring of mothers with a bipolar disorder are at high-risk for impaired developmental outcomes and psychopathology (e. g., mood, anxiety, sleep disorders) later in life. This increased risk of psychopathology is not only because of genetic vulnerability, but environmental factors may play an important role as well. The often long and debilitating mood episodes of mothers with bipolar disorder might hamper their qualities as a caregiver and may impact the child. We examined early mother-to-infant bonding 1 year postpartum in mothers with bipolar spectrum disorder as compared to mothers of the general population. The association between mother-to-infant bonding and the type of bipolar spectrum diagnosis (bipolar I, bipolar II, bipolar Not Otherwise Specified) as well as relapse within 12 months postpartum was also assessed. Methods: In total, 75 pregnant women with a bipolar spectrum disorder participated in the current study. The participants were included in a longitudinal cohort study of women with bipolar spectrum disorder and were prospectively followed from pregnancy until 1 year postpartum. Mother-to-infant bonding was assessed using the Pre- and Postnatal Bonding Scale. A longitudinal population-based cohort of 1,419 pregnant women served as the control group. Multiple linear regression analyses were used to assess the association between bipolar spectrum disorder and mother-to-infant bonding scores, controlling for several confounders. Results: Women with bipolar spectrum disorder perceived the bonding with their child as less positive compared to the control group. The type of bipolar spectrum disorder was not associated with poorer bonding scores. Relapse during the 1st year after delivery also did not affect bonding scores in women with bipolar spectrum disorder. Conclusions: Our findings could imply that women with bipolar spectrum disorder are more vulnerable to impairments in bonding due to the nature of their psychopathology, regardless of the occurrence of postpartum relapse. Careful follow-up including monitoring of mother-to-infant bonding of pregnant women with a history of bipolar spectrum disorder should be a standard to this vulnerable group of women. In addition, regardless of severity and mood episode relapse, an intervention to improve bonding could be beneficial for all mothers with bipolar spectrum disorder and their newborns.

The Dutch Bipolar Offspring Study: Cognitive Development and Psychopathology

Various aspects of the relationship between cognitive impairment and bipolar disorder are not clear yet. This study examines cognitive and educational functioning prospectively in offspring at familial risk for bipolar disorder, in order to improve our understanding of the association between cognitive functioning and psychopathology. Bipolar offspring (N = 92) from the prospective Dutch bipolar offspring study were evaluated at adolescence and adulthood for IQ estimate, educational achievement and development of any psychiatric disorder. The main outcome was IQ estimate after 12 years of follow-up (offspring mean age 28 years). Generalized estimating equation (GEE) analyses showed that any lifetime DSM-IV axis I diagnosis was related to a lower cognitive outcome at adulthood as compared to unaffected bipolar offspring. No specific association was found for type of diagnosis. Early onset psychopathology (diagnosis at or before age 15 years) was significantly related to lower IQ estimate at adulthood, indicating a sensitive period for neurocognitive development.

Neuropsychological Functioning and Temperament Traits in a Czech Sample of Children and Adolescents at Familial Risk of Bipolar Disorder

Background: Although a positive family history is the strongest predictor for bipolar disorder (BD), most offspring of BD parents (BO) will not develop the disorder. Identification of vulnerability markers for BD is essential for specific individual risk estimation. Impairments in cognitive functioning and the presence of specific temperament traits are considered promising candidates. Methods: Sixty-three BO (48% female; 11.8 ± 3.3 years) and 54 control offspring (CO; 44% female; 12.3 ± 3.2 years) comparable in sex (p = 0.4) and age (p = 0.4) were enrolled. Detection of current sub/threshold mood symptoms by the Kiddie Schedule for Affective Disorders and Schizophrenia and General Behavior Inventory was applied to separate BO into ultrahigh-risk (UHR) and high-risk (HR) subgroups. Cognitive functions were tested by the Developmental Neuropsychological Assessment II test battery, d2 Test of Attention, and Amsterdam Neuropsychological Tasks. Temperament was assessed by the Temperament in Middle Childhood and Early Adolescent Temperament Questionnaires. Results: The BO sample consisted of 5 BD, 17 UHR, and 41 HR participants. We did not observe any significant differences between the BO and CO groups or between the UHR, HR, and CO subgroups (Hedges' g = 0.21-0.39) in cognitive functioning. The BO differed significantly in some temperament traits from the CO (g = 0.42-0.61), while the UHR subgroup exhibited lower effortful control and attention focusing than both HR and CO participants (g = 0.92-1.19). Limitations: The cross-sectional design and wide age range of the sample limited our findings. Conclusions: Neuropsychological impairment does not seem to be a trait marker of BD in the premorbid stage. Temperament with low effortful control and low attention focusing might be associated with the development of mood disorders in BO.