Frontal Lobe White Matter Volume Research Articles

Effect of schizophrenia common variants on infant brain volumes: cross-sectional study in 207 term neonates in developing Human Connectome Project

Increasing lines of evidence suggest deviations from the normal early developmental trajectory could give rise to the onset of schizophrenia during adolescence and young adulthood, but few studies have investigated brain imaging changes associated with schizophrenia common variants in neonates. This study compared the brain volumes of both grey and white matter regions with schizophrenia polygenic risk scores (PRS) for 207 healthy term-born infants of European ancestry. Linear regression was used to estimate the relationship between PRS and brain volumes, with gestational age at birth, postmenstrual age at scan, ancestral principal components, sex and intracranial volumes as covariates. The schizophrenia PRS were negatively associated with the grey (β = −0.08, p = 4.2 × 10−3) and white (β = −0.13, p = 9.4 × 10−3) matter superior temporal gyrus volumes, white frontal lobe volume (β = −0.09, p = 1.5 × 10−3) and the total white matter volume (β = −0.062, p = 1.66 × 10−2). This result also remained robust when incorporating individuals of Asian ancestry. Explorative functional analysis of the schizophrenia risk variants associated with the right frontal lobe white matter volume found enrichment in neurodevelopmental pathways. This preliminary result suggests possible involvement of schizophrenia risk genes in early brain growth, and potential early life structural alterations long before the average age of onset of the disease.

Long acting injection versus oral risperidone in first-episode schizophrenia: Differential impact on white matter myelination trajectory

ContextImaging and post-mortem studies provide converging evidence that subjects with schizophrenia (SZ) have a dysregulated trajectory of frontal lobe myelination. Prior MRI studies suggested that early in treatment of SZ, antipsychotic medications initially increase frontal lobe white matter (WM) volume, which subsequently declines prematurely in chronic stages of the disease. Insofar as the trajectory of WM decline associated with chronic disease may be due to medication non-adherence, it may be modifiable by long acting injection (LAI) formulations. ObjectivesExamine the impact of antipsychotic formulation on the myelination trajectory during a randomized six-month trial of LAI risperidone (RLAI) versus oral risperidone (RisO) in first-episode SZ subjects. DesignTwo groups of SZ subjects (RLAI, N=11; and RisO, N=13) that were matched in pre-randomization oral medication exposure and 14 healthy controls (HCs) were prospectively examined. Frontal lobe WM volume was estimated using inversion recovery (IR) MRI images. A brief neuropsychological battery that focused on reaction times was performed at the end of the study. Main outcome measureWM volume change scores. ResultsWM volume remained stable in the RLAI and decreased significantly in the RisO groups resulting in a significant differential treatment effect, while the HC had a WM change intermediate and not significantly different from the two SZ groups. WM increase was associated with faster reaction times in tests involving frontal lobe function. ConclusionsThe results suggest that RLAI may improve the trajectory of myelination in first-episode patients and have a beneficial impact on cognitive performance. Better adherence provided by LAI may underlie the modified trajectory of myelin development. In vivo MRI biomarkers of myelination can help clarify mechanisms of action of treatment interventions.

Differential effects of typical and atypical antipsychotics on brain myelination in schizophrenia

Context Imaging and post-mortem studies provide converging evidence that patients with schizophrenia have a dysregulated developmental trajectory of frontal lobe myelination even in adulthood. Atypical antipsychotics have been shown to have a wide spectrum of efficacy across multiple psychiatric diseases and to be particularly efficacious in treatment resistant cases of disorders such as schizophrenia. Objective To test the a priori hypothesis that antipsychotic medications may differentially impact frontal lobe myelination in patients with schizophrenia. Design, setting, and participants Participants ranged in age from 18–35 years, were all male, and were recruited by a single group of investigators using the same criteria. Two cohorts of subjects with schizophrenia early in their disease who were treated either with oral risperidone (Ris) or fluphenazine decanoate (Fd) were imaged in conjunction with cohorts of healthy controls. Each cohort was imaged using a different MRI instrument using identical imaging sequences. Main outcome measure MRI measures of frontal lobe white matter volume. Results We estimated differences due to differences in the MRI instruments used in the two studies in the two healthy control groups matched to the patient samples, adjusting for age and other covariates. We then statistically removed those differences (which we assumed were due to instrument effects) from the data in the schizophrenia samples by subtraction. Relative to the differences seen in controls, the two groups of schizophrenic patients differed in their pattern of frontal lobe structure with the Ris-treated group having significantly larger white matter volume than the Fd group. Conclusions The results suggest that the choice of antipsychotic treatment may differentially impact brain myelination in adults with schizophrenia. Prospective studies are needed to confirm this finding. MRI can be used to dissect subtle differences in brain tissue characteristics and thus could help clarify the effect of pharmacologic treatments on neurodevelopmental and pathologic processes in vivo.

Progressive Structural Brain Abnormalities and Their Relationship to Clinical Outcome

Many studies have shown that structural brain abnormalities in schizophrenia are already present by the time of index evaluation of first-episode patients. However, whether these abnormalities progressively worsen during the subsequent course of the disorder remains unresolved. To study the longitudinal progression of structural brain abnormalities, high-resolution multispectral magnetic resonance images obtained on 73 recent-onset schizophrenic patients and 23 controls were analyzed using state-of-the-art, well-validated, and highly reliable neuroimaging tools. The mean duration between initial and follow-up MRIs was 3 years. Repeated-measures analysis of covariance was carried out to determine (1) whether brain volume changes differed between patients and controls and (2) the significance of regional brain changes on functional outcome in schizophrenia. We found accelerated enlargement in cortical sulcal cerebrospinal fluid spaces early in the course of schizophrenia. Instead of the usual trajectory of volume enlargement, patients showed progressive reduction in frontal lobe white matter volume. A reciprocal increase in frontal lobe cerebrospinal fluid volume also occurred at a more rapid rate in patients than in controls. In keeping with most of our a priori hypotheses, patients with poor outcome had greater lateral ventricular enlargement over time than patients with good outcome. Progressive decrement in frontal lobe white matter volume and enlargement in frontal lobe cerebrospinal fluid volume were associated with greater negative symptom severity. Reductions in frontal lobe gray and white matter volumes correlated with poorer executive functioning. There are ongoing changes in the brains of schizophrenic patients during the initial years after diagnosis despite ongoing antipsychotic drug treatment. These progressive changes seem to be most evident in the frontal lobes and to correlate with functional impairment. Disruptions in neurodevelopment or neural plasticity may act alone or in combination to bring about these progressive brain deficits in schizophrenia.

White Matter Structural Integrity in Healthy Aging Adults and Patients With Alzheimer Disease

Imaging and postmortem studies suggest that frontal lobe white matter (FLWM) volume expands until about the age of 44.6 years and then declines. Postmortem evidence indicates that the structural integrity of myelin sheaths deteriorates during normal aging, especially in late myelinating regions such as the frontal lobes. To assess the integrity of FLWM by magnetic resonance imaging and, thus, to provide an important index of brain aging and its relationship to Alzheimer disease (AD). Cross-sectional study. Two metropolitan university hospitals and AD research centers. Two hundred fifty-two healthy adults (127 men and 125 women), aged 19 to 82 years, and 34 subjects with AD (16 men and 18 women), aged 59 to 85 years. Calculated transverse relaxation rate (R( 2)) of the FLWM (an indirect measure of the structural integrity of white matter). As expected from prior imaging data on FLWM volume, the quadratic function best represented the relationship between age and the FLWM R(2) (P<.001). In healthy individuals, the FLWM R(2) increased until the age of 38 years and then declined markedly with age. The R( 2) of subjects with AD was significantly lower than that of a group of healthy control subjects who were of similar age and sex (P<.001). The R(2) changes in white matter suggest that the healthy adult brain is in a constant state of change, roughly defined as periods of maturation continuing into middle age followed by progressive loss of myelin integrity. Clinically diagnosed AD is associated with more severe myelin breakdown. Noninvasive measures, such as the determination of the R(2), may have the potential to track prospectively the trajectory of deteriorating white matter integrity during normal aging and the development of AD and, thus, may be a useful marker for medication development aimed at the prevention of AD.

Apolipoproteins E and C1 and brain morphology in memory impaired elders.

Previous research has shown that polymorphisms of the apolipoproteins E ( APOE) and APOC1 represent genetic risk factors for dementia and for cognitive impairment in the elderly. The brain mechanisms by which these genetic variations affect behavior or clinical severity are poorly understood. We studied the effect of APOE and APOC1 genes on magnetic resonance imaging measures in a sample of 50 subjects with age-associated memory impairment. The APOE E4 allele was associated with reduced left hippocampal volumes and APOE*E3 status was associated with greater frontal lobe white matter volumes. However, no APOE effects were observed when analyses accounted for other potential confounding variables. The effects of APOC1 on hippocampal volumes appeared to be more robust than those of the APOE polymorphism. However, no modulatory effects on brain morphology outside the medial temporal lobe region were observed when demographic variables, clinical status, and other anatomical brain measurements were taken into consideration. Our results suggest that the role of the APOC1 polymorphism in brain morphology of the cognitively impaired elderly should be examined in further studies.

Smaller frontal lobe white matter volumes in depressed adolescents

Background Prior studies have demonstrated reduced frontal lobe volumes in depressed adolescents. In this study, frontal lobe gray and white matter volumes in adolescents with major depressive disorder were evaluated. Methods Nineteen depressed and thirty-eight healthy comparison adolescents were recruited for a magnetic resonance imaging study. Images were segmented into gray matter, white matter, and cerebrospinal fluid. Morphometric measurements of the whole brain and frontal lobe region were completed. Results Whole brain volumes were significantly smaller in depressed subjects compared with the healthy comparison subjects. Significantly smaller frontal white matter volumes and significantly larger frontal gray matter volumes were found in the depressed subjects, after controlling for age and whole brain volume. Conclusions These results are consistent with the hypothesis that a deficit in frontal volume exists during cortical development in adolescents with depression. Further studies are needed to assess whether volume differences resolve over time and the extent to which these differences influence response to treatment.

Cerebral Lobes in Autism: Early Hyperplasia and Abnormal Age Effects

Metabolic, functional, behavioral, and histologic studies suggest that the structure of the cerebrum may be abnormal in autism. In a previous cross-sectional study we found abnormal enlargement of cerebral cortex and cerebral white matter volumes in autistic 2 and 3 year olds and abnormally slow rates of volume change across later ages. In the present study, we assessed whether these volume abnormalities are limited to particular cerebral regions or are pervasive throughout the cerebrum. We used magnetic resonance imaging (MRI) to quantify volumes of cerebral lobes (frontal, temporal, parietal, and occipital regions), using classic sulcal boundaries to define regions. We examined 38 boys with autism and 39 normal control boys between the ages of 2 and 11 years. Several regions showed signs of gray matter and white matter hyperplasia in 2- and 3-year-old patients (as much as 20% enlargement), but there appeared to be an anterior to posterior gradient in the degree of hyperplasia. The frontal lobe showed the greatest enlargement while the occipital lobe was not significantly different from normal. Gray and white matter differences were not found in the older children. By examining the relationships between regional volumes and subject age, we found that frontal, temporal, and parietal white matter volumes, as well as frontal and temporal gray matter volumes, changed at significantly slower rates in autism patients than in controls across the 2- to 11-year-age range. For example, frontal lobe white matter volume increased by about 45% from 2–4 years of age to 9–11.5 years, but by only 13% in autistic patients. Mechanisms that might account for early hyperplasia are discussed as they might relate to the regional differences in degree of abnormality. For instance, possible influences of neurotrophic factors, or of abnormal afferent activity from other affected brain regions are considered.

Frontal lobe volume in patients with Huntington's disease.

Neuropathologic and neuroimaging studies have suggested that frontal lobes are affected in Huntington's disease (HD), and that atrophy in this region may be associated with some of the cognitive impairment and clinical decline observed in patients with HD. We measured gray and white matter volumes within the frontal lobes on MRI for 20 patients with HD (10 mildly affected and 10 moderately affected) and 20 age- and sex-matched control subjects. We also correlated frontal lobe measurements with measures of symptom severity and cognitive function. Patients who were mildly affected had frontal lobe volumes (both gray and white matter) essentially identical to those of control subjects, despite clearly abnormal basal ganglia. Patients who were moderately affected demonstrated significant reductions in total frontal lobe volume (17%) and frontal white matter volume (28%). Frontal lobe white matter volume reductions, but not total frontal lobe volume reductions, were disproportionately greater than overall brain volume reductions (17%). Frontal lobe volume correlated with symptom severity and general cognitive function, but these correlations did not remain significant after taking into account total brain volume. We conclude that cognitive impairment and symptom severity are associated with frontal lobe atrophy, but this association is not specific to the frontal lobes. Frontal lobe atrophy (like total brain atrophy) occurs in later stages of increasing HD symptom severity and this atrophy primarily involves white matter.