Diffusion tensor imaging in first degree relatives of schizophrenia and bipolar disorder patients

Abstract

Objectives White matter (WM) abnormalities are one of the most widely and consistently reported findings in schizophrenia (SZ) and bipolar disorder (BD). If these abnormalities are inherited determinants of illness, suitable to be classified as an endophenotype, relatives of patients must also have them at higher rate compared to the general population. In this review, we evaluate published diffusion tensor imaging (DTI) studies comparing first degree relatives of SZ and BD patients and healthy control subjects. Methods We searched PubMed, Embase and PsychInfo for DTI studies which included an unaffected relative and a healthy comparison group. Results 22 studies fulfilled the inclusion criteria. WM abnormalities were found in many diverse regions in relatives of SZ patients. Although the findings were not completely consistent across studies, the most implicated areas were frontal and temporal WM regions and the corpus callosum. Studies in relatives of BD patients were fewer in number with less consistent findings reported across studies. Conclusions Our review supports the concept of WM abnormalities as an endophenotype in SZ, with somewhat weaker evidence in BD, but larger and higher quality studies are needed to make a definitive comment.

Differential Time Course of Microstructural White Matter in Patients With Psychotic Disorder and Individuals at Risk: A 3-Year Follow-up Study

“…20 Regarding the present finding of a patient-control difference in this region, current and previous cross-sectional DTI findings 50 in siblings may be suggestive of a WM intermediate phenotype.…”

Neurobiology of Risk for Bipolar Disorder

“…Some studies found abnormalities in the superior longitudinal fasciculus, inferior longitudinal fasciculus, corpus callosum, right uncinate fasciculus, right inferior fronto-occipital fasciculus, right anterior limb of internal capsule, and thalamic radiation in both BD-P and BD-FDR [68•, 69], while two studies did not find any abnormalities in older relative groups compared with controls [70, 71]. A population-based study showed abnormalities in similar white matter tracts in adolescents with subthreshold bipolar symptoms [72].…”

“…A population-based study showed abnormalities in similar white matter tracts in adolescents with subthreshold bipolar symptoms [72]. These tracts connect regions implicated in the identification and regulation of emotion, attention, impulsivity, response inhibition, set shifting, and risk-taking [68•]. Decreased WM volume is highly associated with genetic risk and familiality in BD [70–74].…”

“…Decreased WM volume is highly associated with genetic risk and familiality in BD [70–74]. However, the results are neither consistent nor robust enough to indicate replicable WM abnormalities in BD-FDR, thus not supportive of the WM abnormalities as an endophenotype of BD, whereas more WM abnormalities in SCH conform better to the concept of endophenotype [68•, 73]. …”

784. Structural Dysconnectivity of Key Cognitive and Emotional Hubs in Young People at High Genetic Risk for Bipolar Disorder

“…CN subjects were recruited via print and electronic media, and noticeboards in universities and local communities. Sample ascertainment and separate clinical assessments for younger (15)(16)(17)(18)(19)(20)(21) and older (22)(23)(24)(25)(26)(27)(28)(29)(30) age categories are provided in Perich et al 36 and in Supplementary Information 1.1. We pooled data across both age cohorts unless there was a specific correlation between a brain network measure and an age-specific clinical variable in either group.…”