Dermatoglyphics in relation to brain volumes in twins concordant and discordant for bipolar disorder

Fingerprint patterns in relation to an altered neurodevelopment in patients with autism spectrum disorder

Dermatoglyphic patterns are permanently established and matured before the 24th week of gestation. Their frequencies and localization might be a good indicator of developmental instability in individuals with an altered neurodevelopment and show potential as biomarkers of autism spectrum disorder (ASD). In this study, fingerprint pattern counts and fluctuating asymmetry in the distribution of patterns are compared between 67 boys diagnosed with ASD (aged 5.11 ± 2.51 years) and 83 control boys (aged 8.58 ± 3.14 years). Boys with ASD had a higher rate of discordance in their fingerprint patterns (p = .0026), showing more often bilateral differences in the occurrence of certain patterns. A chi-square test revealed that the difference in pattern frequencies between boys with ASD and the control group is the most significant in frequencies of whorls, tented arches, and ulnar loops. Boys with ASD have significantly fewer ulnar loops, significantly more whorls, and tented arches in the right hand. The achieved results are in favor of the suggestion that prenatal influences, which play a role in the development of bilateral differences in fingerprint patterns up to the 24th week of gestation, may be a potential cause of an altered neurodevelopment in ASD individuals.

Refining the resolution of craniofacial dysmorphology in bipolar disorder as an index of brain dysmorphogenesis

As understanding of the genetics of bipolar disorder increases, controversy endures regarding whether the origins of this illness include early maldevelopment. Clarification would be facilitated by a 'hard' biological index of fetal developmental abnormality, among which craniofacial dysmorphology bears the closest embryological relationship to brain dysmorphogenesis. Therefore, 3D laser surface imaging was used to capture the facial surface of 21 patients with bipolar disorder and 45 control subjects; 21 patients with schizophrenia were also studied. Surface images were subjected to geometric morphometric analysis in non-affine space for more incisive resolution of subtle, localised dysmorphologies that might distinguish patients from controls. Complex and more biologically informative, non-linear changes distinguished bipolar patients from control subjects. On a background of minor dysmorphology of the upper face, maxilla, midface and periorbital regions, bipolar disorder was characterised primarily by the following dysmorphologies: (a) retrusion and shortening of the premaxilla, nose, philtrum, lips and mouth (the frontonasal prominences), with (b) some protrusion and widening of the mandible-chin. The topography of facial dysmorphology in bipolar disorder indicates disruption to early development in the frontonasal process and, on embryological grounds, cerebral dysmorphogenesis in the forebrain, most likely between the 10^th and 15^th week of fetal life.

A meta-analysis of neurocognition in youth with familial high risk for bipolar disorder

Objective:

Neuropsychological impairment, including deficits in social cognition is evident in subjects at genetic high-risk for psychosis. However, findings in youth at genetic risk to bipolar disorder (BP) have been suggested to be less supportive of premorbid deficits. We aimed to conduct a meta-analysis of cognitive deficits in youth with familiar risk for bipolar disorder (FHR-BD).

Methods:

A novel meta-analysis of FHR-BD (mean age 10–25), including 18 studies (786 offsprings/siblings of patients with BD and 794 healthy controls), was conducted.

Results:

Both general cognition (d = 0.29, CI = 0.15–0.44) and social cognition (d = 0.23, CI = 0–0.45) were impaired in FHR-BD. In comparison to controls, FHR-BD had significant deficits in several cognitive domains, including visual memory (d = 0.35), verbal memory (d = 0.21), processing speed (d = 0.26) and sustained attention (d = 0.36). There was no significant difference between FHR-BD and controls in planning and working memory.

Conclusions:

Cognitive deficits are evident in individuals who are at genetic high-risk for developing BD. Neurodevelopmental abnormalities are likely playing a role not only in schizophrenia but also in BD.

Neurodevelopmental pathways in bipolar disorder

Aberrations in neurodevelopmental trajectories have been implicated in the neurobiology of several mental disorders and evidence indicates a pathophysiological and genetic overlap of schizophrenia and bipolar disorder (BD). In this narrative review, we summarize findings related to developmental and perinatal factors as well as epidemiological, clinical, neuropsychological, brain imaging, postmortem brain and genomic studies that provide evidence for a putative neurodevelopmental pathogenesis and etiology of BD. Overall, aberrations in neurodevelopmental pathways have been more consistently implicated in the pathophysiology of schizophrenia compared to BD. Nevertheless, an accumulating body of evidence indicates that dysfunctional neurodevelopmental pathways may be implicated in the underlying pathophysiology of at least a subset of individuals with BD particularly those with an early age of illness onset and those exhibiting psychotic symptoms. A heuristic neurodevelopmental model for the pathophysiology of BD based on the findings of this review is proposed. Furthermore, we critically discuss clinical and research implications of this model. Finally, further research directions for this emerging field are provided.

Disease-discordant twin structural MRI studies on affective disorders

Magnetic resonance imaging (MRI) studies have identified neural structures implicated in the pathophysiology of mood disorders, especially bipolar disorder (BD) and major depressive disorder (MDD). However, the role of genetic and environmental influences on such brain deficits is still unclear. In this context, the present review summarizes the current evidence from structural MRI and Diffusion Tensor Imaging (DTI) studies on twin samples concordant or discordant for BD or MDD, with the aim of clarifying the role of genetic and environmental risk factors on brain alterations. Although the results showed a complex interplay between gene and environment in affective disorders, the evidence seem to underline that both genetic and environmental risk factors have an impact on brain areas and vulnerability to MDD and BD. However, the precise mechanism of action and the interaction between these factors still needs to be unveiled. Therefore, future larger studies on concordant or discordant twins should be encouraged, because this population provides a unique opportunity to probe separately genetic and environmental markers of disease vulnerability.

Maternal stress, prenatal medical illnesses and obstetric complications: Risk factors for schizophrenia spectrum disorder, bipolar disorder and major depressive disorder

Maternal stress and medical illnesses during early life are well-documented environmental indicators of an increased risk of schizophrenia. Few studies, conversely, have confirmed an association with major affective disorders. The present study examined the impact of maternal stress, medical illnesses and obstetric complications on the development of severe mental disorder in 240 patients with a diagnosis of schizophrenia spectrum disorder, bipolar disorder, or major depressive disorder and matched with 85 controls. Mothers of participants were asked about stressful events during pregnancy using the Social Readjustment Scale; information on prenatal/perinatal illnesses were acquired from medical records. Schizophrenia spectrum disorder was positively associated with maternal stress (OR = 2.16), infections (OR = 7.67), inadequate weight gain (OR = 9.52) during pregnancy, and peripartum asphyxia (OR = 4.00). An increased risk of bipolar disorder was associated with head circumference < 32 cm at birth (OR = 5.40) and inversely with inadequate weight gain (OR = 0.29). Major depressive disorder diagnosis was inversely related to inadequate weight gain (OR = 0.22). These results support a role for maternal stress, medical illnesses and obstetric complications as risk factors for subsequent severe mental illness in adulthood. Further research is needed, especially with regard to affective disorders.

Meta-analysis of longitudinal studies of cognition in bipolar disorder: comparison with healthy controls and schizophrenia

BACKGROUND

Bipolar disorder (BP) is associated with significant cognitive impairment. Recent evidence suggests that cognitive deficits are already evident after first-episode mania. However, it is not clear whether BP is associated with further decline in cognitive functions in individuals with established illness. Aim of this meta-analytic review was to examine longitudinal neurocognitive changes in BP and to compare trajectory of cognitive deficits in BP with schizophrenia and healthy controls.

METHODS

Electronic databases were searched for the studies published between January 1987 and November 2016. In total 22 reports were included in the current meta-analysis. The main analysis assessed the longitudinal change in cognition in 643 patients with BP. Further analyses were conducted in studies investigating cognitive changes in BP along with healthy controls (459 BP and 367 healthy controls) and schizophrenia (172 BP and 168 schizophrenia).

RESULTS

There was no cognitive decline overtime neither in short-term (mean duration = 1.5 years) nor in long-term (mean duration = 5.5 years) follow-up studies in BP. In contrast, there was evidence for modest improvements in task performance in memory and working memory at follow-up. The trajectory of cognitive functioning in BP was not significantly different from changes in schizophrenia and healthy controls.

CONCLUSIONS

Together with the findings in early BP and individuals at genetic risk for BP, current findings suggest that neurodevelopmental factors might play a significant role in cognitive deficits in BP and do not support the notion of progressive cognitive decline in most patients with BP.

Twin studies for the investigation of the relationships between genetic factors and brain abnormalities in bipolar disorder

The pathogenesis of bipolar disorder (BD) is to date not entirely clear. Classical genetic research showed that there is a contribution of genetic factors in BD, with high heritability. Twin studies, thanks to the fact that confounding factors as genetic background or family environment are shared, allow etiological inferences. In this work, we selected twin studies, which focus on the relationship between BD, genetic factors and brain structure, evaluated with magnetic resonance imaging. All the studies found differences in brain structure between BD patients and their co-twins, and also in respect to healthy controls. Genetic effects are predominant in white matter, except corpus callosum, while gray matter resulted more influenced by environment, or by the disease itself. All studies found no interactions between BD and shared environment between twins. Twin studies have been demonstrated to be useful in exploring BD pathogenesis and could be extremely effective at discriminating the neural mechanisms underlying BD.