Developmental differences in white matter architecture between boys and girls

Previous studies have found developmental differences between males and females in brain structure. During childhood and adolescence, relative white matter volume increases faster in boys than in girls. Sex differences in the development of white matter microstructure were investigated in a cohort of normal children ages 5-18 in a cross-sectional diffusion tensor imaging (DTI) study. Greater fractional anisotropy (FA) in boys was shown in associative white matter regions (including the frontal lobes), while greater FA in girls was shown in the splenium of the corpus callosum. Greater mean diffusivity (MD) in boys was shown in the corticospinal tract and in frontal white matter in the right hemisphere; greater MD in girls was shown in occipito-parietal regions and the most superior aspect of the corticospinal tract in the right hemisphere. Significant sex-age interactions on FA and MD were also shown. Girls displayed a greater rate of fiber density increase with age when compared with boys in associative regions (reflected in MD values). However, girls displayed a trend toward increased organization with age (reflected in FA values) only in the right hemisphere, while boys displayed this trend only in the left hemisphere. These results indicate differing developmental trajectories in white matter for boys and girls and the importance of taking sex into account in developmental DTI studies. The results also may have implications for the study of the relationship of brain architecture with intelligence.     

Corpus callosum signal intensity in patients with bipolar and unipolar disorder

BACKGROUND: Anatomical abnormalities in the corpus callosum have been reported in magnetic resonance imaging (MRI) studies in patients with bipolar but not unipolar disorder. MRI signal intensity can be used as a putative index of corpus callosum myelination. OBJECTIVES: To measure MRI signal intensity in patients with bipolar and unipolar disorder to investigate abnormalities of corpus callosum myelination. METHODS: The study involved 29 DSM-IV bipolar patients (mean (SD) age, 35 (11) years; 16 male, 13 female), 23 DSM-IV unipolar patients (41 (10) years; 4 male, 19 female), and 36 healthy controls (37 (10) years; 23 male, 13 female). A 1.5T GE Signa magnet was employed, with a fast spin echo sequence. Corpus callosum signal intensity was obtained blindly using the semiautomated software NIH Image 1.62. RESULTS: Bipolar patients had lower corpus callosum signal intensity for all callosal subregions (genu, anterior and posterior body, isthmus, splenium) than healthy controls (ANCOVA, age and sex as covariates, p<0.05). No significant differences were found between unipolar and healthy subjects (ANCOVA, age and sex as covariates, p>0.05). CONCLUSIONS: The findings suggest abnormalities in corpus callosum white matter in bipolar but not unipolar patients, possibly because of altered myelination. Such abnormalities could lead to impaired interhemispheric communication in bipolar disorder. Longitudinal MRI studies involving first episode and early onset bipolar patients will be necessary for a better understanding of the potential role of abnormalities of corpus callosum myelination in the pathophysiology of bipolar disorder.     

磁共振成像对肾上腺脑白质营养不良的诊断价值

报告４例肾上腺脑白质营养不良（ＡＬＤ）患者的磁共振成像（ＭＲＩ）表现。ＭＲＩ表现为双侧对称的白质异常信号，主要位于枕、顶、颞叶，视放射和胼胝体压部，Ｔ１加权为低信号，Ｔ２加权为高信号，有增强效应。多维成像和高对比强度使ＭＲＩ比ＣＴ有更强的敏感性，能明确病变的部位及其严重程度，故ＭＲＩ是诊断ＡＬＤ的有效手段。     

Magnetic resonance imaging after corpus callosotomy

Magnetic resonance imaging (MRI) can visualize the extent of corpus callosotomy performed for medically intractable epilepsy not amenable to focal surgery. Five patients underwent complete callosotomy and one an anterior callosotomy, aged 19 to 24 years, 21 to 53 months (prior to scanning). T1 images showed complete absence of the callosal shadow in five cases and visualization of the genu and splenium in the sixth case. T2-weighted pulse sequence spin-echo MRI showed intense image throughout the region of the entire callosum in the two cases with the longest postoperative course. The two middle cases showed intense T2 signal from the splenium, and the two latest showed no increase in T2 signal. We believe the increase in T2 signal in the transected callosum may represent an in vivo example of anisomorphic gliosis. T1 images demonstrate the anatomic extent of transection, while T2 images demonstrate the chemical and pathophysiologic sequence of transection. Thus, MRI is the imaging test of choice to evaluate callosotomy patients.     

EEG development of healthy boys and girls. Results of a longitudinal study

This longitudinal study has extended an earlier cross-sectional one in order to investigate the development of background activity and the topographical distribution of different EEG parameters during childhood and adolescence. Ninety-six healthy children (47 boys and 49 girls) were followed for up to 7 years with serial EEGs. These were analysed by spectral analysis. Power spectra were calculated for conventional frequency bands. Three topics were followed: (i) differentiation between inter-individual and age-related changes, (ii) evaluation of sex differences and (iii) evaluation of developmental velocity of different EEG parameters. Between 4 and 17 years the content of theta waves decreases and the content of alpha waves increases. In girls more than in boys, slow alpha waves (7.5-9.5 c/sec) in occipital leads first increase, as theta decreases. Later they decrease themselves while fast alpha waves (9.5-12.5 c/sec) increase. The velocity of occipital changes is almost twice that centrally, and is greater in early childhood than after 10 years of age. Girls under 6 years of age show significantly more theta and less alpha waves compared with boys. However, the developmental velocity (change per year) is higher in girls than in boys and continues for a longer time; thus girls catch up with age-related changes of the boys by a later developmental spurt. Individual characteristics of the subjects determine the EEG twice as much as the age factor; this explains the wide range of results in previous studies. No trend was found to suggest earlier maturation in one hemisphere while in 5% of the subjects the amount of activity for one parameter in one hemisphere exceeds 1.5 times the amount of activity in the other. The individual characteristics of the EEG spectra show a remarkable stability over the years.     

Sex differences in brain maturation in maltreatment-related pediatric posttraumatic stress disorder

BACKGROUND: Recent investigations suggested that pediatric posttraumatic stress disorder (PTSD) is associated with adverse brain development. However, sex differences are poorly understood. METHODS: In this study, 61 medically healthy children and adolescents (31 males and 30 females) with chronic PTSD secondary to abuse, who had similar trauma and mental health histories, and 122 healthy controls (62 males and 60 females) underwent comprehensive psychiatric assessments and an anatomical MRI brain scan. RESULTS: When gender groups were analyzed separately, findings of larger prefrontal lobe CSF volumes and smaller midsagittal area of the corpus callosum subregion 7 (splenium) were seen in both boys and girls with maltreatment-related PTSD compared to their gender-matched comparison subjects. Subjects with PTSD did not show the normal age related increases in the area of the total corpus callosum and its region 7 (splenium) compared to non-maltreated subjects; however, this finding was more prominent in males with PTSD. Significant sex by group effects demonstrated smaller cerebral volumes and corpus callosum regions 1 (rostrum) and 6 (isthmus) in PTSD males and greater lateral ventricular volume increases in maltreated males with PTSD than maltreated females with PTSD. CONCLUSIONS: These data suggest that there are sex differences in the brain maturation of boys and girls with maltreatment-related PTSD. Longitudinal MRI brain investigations of childhood PTSD and the relationship of gender to psychosocial outcomes are warranted.     

Linear and curvilinear correlations of brain white matter volume,fractional anisotropy,and mean diffusivity with age using voxel‐based and region‐of‐interest analyses in 246 healthy children

In this study, we examined linear and curvilinear correlations of fractional anisotropy (FA), mean diffusivity (MD), and white matter volume with age by using brain structural and diffusion‐tensor magnetic resonance imaging (MRI) in a large number of healthy children and voxel‐based morphometry (VBM) and region‐of‐interest (ROI) analyses. We collected data by brain structural MRI in 246 healthy children, aged 5–18 years. FA and MD images were normalized using the normalization parameter of the corresponding structural MRI. Next, we analyzed the correlations between FA and age and between MD and age by estimating linear and logarithmic functions. We also analyzed the correlation between white matter volume and age by linear, quadratic, and cubic functions. Correlations between FA and age and between MD and age showed exponential trajectories in most ROIs in boys and girls, except for several fibers, such as the corpus callosum connecting the bilateral rectal gyri in boys. The correlation between white matter volume and age showed significant positive linear trajectories in most ROIs in boys and girls, except for a few fibers, such as the bilateral uncinate fasciculus. Additionally, maturational rates differed among major fibers, and in girls, the left superior longitudinal fasciculus, which connects the frontal and temporal lobes, showed a slower rate of maturation than other fibers. Our results may help to clarify the mechanisms of normal brain maturation from the viewpoint of brain white matter. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.     

Voxel-based analysis of white matter during adolescence and young adulthood

Purpose: To evaluate differences in age-related brain white matter by voxel-based analysis of healthy adolescents and young adults. Materials and methods: Echo-planar diffusion-tensor magnetic resonance (MR) imaging was performed in healthy subjects of 3 groups (aged 11–13, 16–18 and 23–25, respectively). Linear correlative analyses were applied to determining age-related fractional anisotropy (FA) and mean diffusivity (MD), and t-test was performed to compare FA and mean diffusion maps between different age groups. Results: Significant positive correlation of FA with age was found in the internal capsule, the external capsule, the frontal white matter, and the body and genu of the corpus callosum. Compared with the 11–13 age group, FA in the 16–18 age group increased in the internal capsule, the frontal white matter, the body and the splenium of the corpus callosum. Compared to the 16–18 age group, FA in the 23–25 age group increased in the frontal white matter, the posterior limb of internal capsule, and the genu of the corpus callosum. Statistically significant negative correlation of the mean diffusion with age was found in the frontal and parietal white matter. Compared with the 11–13 age group, MD in the 16–18 age group decreased in the prefrontal and the temporo-parietal white matter. Compared with the 16–18 age group, MD in the 23–25 age group decreased in the frontal white matter. Conclusion: Diffusion-tensor MR imaging results indicate that white matter maturation assessed at different ages involves increases in FA and decreases in mean diffusion of the white matter during adolescence and young adulthood. FA and mean diffusion may reflect different physiologic processes in healthy adolescents and young adults. Taken together, these data show that maturation of white matter is an important part of brain maturation during adolescence and young adulthood.     

Quantitative microstructural cerebral changes in neurofibromatosis type 1

Objectives

To evaluate microstructural cerebral changes in children with neurofibromatosis type 1 (NF1) based on T₂ relaxation time measurements at 3Tesla.

Evolution of nerve conduction velocity in later childhood and adolescence

Sensory and/or motor nerve conduction velocities (NCVs) were measured in median, radial, sural, and peroneal nerves of 54 healthy girls and 75 healthy boys aged 3–19 years. Independent of the nerve and sex, both motor and sensory NCVs increased in the upper extremities and decreased in the lower ones as a function of age/growth in length. NCV increased in the upper limbs on an average 3.17 m/sec in the boys and in the girls 1.47 m/sec per 10 years of life. As for the nerves of the lower extremities, NCV slowed down on the average 1.81 m/sec in the boys and in the girls 3.62 m/sec per 10 years of age. The change varied in different nerves. A highly significant one (P <0.001) was found in both the motor and sensory NCVs of peroneal nerve in the girls and in the sensory NCV of radial nerve in boys. On the average NCV was in most nerves faster in the girls than in boys of the same age. According to these results, changes occur in the function—and thus probably also in the morphology—of peripheral nerves even in later childhood and adolescence. These changes pertain to general maturation, growth in length of the limbs, and possibly also sex.     

The role of testosterone and estradiol in brain volume changes across adolescence: A longitudinal structural MRI study

It has been postulated that pubertal hormones may drive some neuroanatomical changes during adolescence, and may do so differently in girls and boys. Here, we use growth curve modeling to directly assess how sex hormones [testosterone (T) and estradiol (E₂)] relate to changes in subcortical brain volumes utilizing a longitudinal design. 126 adolescents (63 girls), ages 10 to 14, were imaged and restudied ～2 years later. We show, for the first time, that best‐fit growth models are distinctly different when using hormones as compared to a physical proxy of pubertal maturation (Tanner Stage) or age, to predict brain development. Like Tanner Stage, T and E₂ predicted white matter and right amygdala growth across adolescence in both sexes, independent of age. Tanner Stage also explained decreases in both gray matter and caudate volumes, whereas E₂ explained only gray matter decreases and T explained only caudate volume decreases. No pubertal measures were related to hippocampus development. Although specificity was seen, sex hormones had strikingly similar relationships with white matter, gray matter, right amygdala, and bilateral caudate volumes, with larger changes in brain volume seen at early pubertal maturation (as indexed by lower hormone levels), followed by less robust, or even reversals in growth, by late puberty. These novel longitudinal findings on the relationship between hormones and brain volume change represent crucial first steps toward understanding which aspects of puberty influence neurodevelopment. Hum Brain Mapp 35:5633–5645, 2014. © 2014 Wiley Periodicals, Inc .     

Prediction from low birth weight to female adolescent depression: a test of competing hypotheses

CONTEXT: Low birth weight (LBW) predicts later-onset hypertension and diabetes mellitus. Its role as a predictor of depression is unclear. OBJECTIVES: To examine whether LBW predicts depression in male and female children and adolescents and to compare the following 2 hypotheses: Low birth weight is one among several perinatal, childhood, and adolescent risk factors for depression (biopsychosocial hypothesis). Low birth weight is a marker for poor intrauterine conditions that provoke adjustments in fetal development, with long-term consequences for stress response (fetal programming hypothesis). DESIGN: A representative population-based sample from an 11-county area in western North Carolina was assessed annually for psychiatric disorders between the ages of 9 and 16 years. We tested the prediction from LBW and depression in models that included LBW only, LBW plus other prenatal and perinatal adversities, LBW plus significant perinatal and childhood adversities, and LBW plus significant perinatal and childhood adversities and adolescent correlates. SETTING: Academic research. PARTICIPANTS: There were 1420 participants, of whom 49% were female. Main Outcome Measure Cumulative prevalence of DSM-IV depressive disorder at 1 assessment or more during childhood (age range, 9-12 years) and during adolescence (age range, 13-16 years). RESULTS: The cumulative prevalence of depression among adolescent girls with LBW was 38.1% (95% confidence interval [CI], 16.3%-66.0%) compared with 8.4% (95% CI, 5.2%-13.3%) among adolescent girls with normal birth weight. Rates among children and adolescent boys did not exceed 4.9%. In adolescence, there was a significant interaction between LBW and sex (odds ratio, 0.2 [95% CI, 0.1-0.5]; P<.001). Low birth weight predicted female adolescent depression after controlling for other perinatal, childhood, and adolescent adversities. Girls with LBW and normal birth weight with no adversities had no adolescent depression, but each additional adversity increased the risk of in girls with LBW more than in girls with normal birth weight. Low birth weight did not predict other psychiatric disorders in either sex. CONCLUSIONS: Low birth weight predicts depression in adolescent girls but not boys. Data support fetal programming over the biopsychosocial hypothesis, suggesting vulnerability to adversities in girls with LBW after puberty.     

Change in adolescents' internalizing symptomatology as a function of sex and the timing of maternal depressive symptomatology

ObjectiveThe purpose of this exploratory study was to examine change in internalizing symptoms from late childhood (age 10) into mid-adolescence (age 15) in a nationally representative sample of Canadian children. The roles of a child's sex, maternal depressive symptoms in late childhood, and their interactions were investigated.MethodThe sample was derived from the National Longitudinal Survey of Children and Youth. Mothers reported on their own depressive symptoms and children reported on their own internalizing symptoms at three time (T) points (T1: 1994/1995; T2: 1996/1997; T3: 1998/1999). Change in children's internalizing symptoms was investigated using multiple regression.ResultsGirls increased and boys decreased in their internalizing symptoms from T1 to T3. The effect of maternal depressive symptoms at T1 was moderated by sex and remained significant after controlling for maternal depressive symptoms at T2 and T3, with more adverse effects in girls.ConclusionsThe internalizing symptoms of girls increased from childhood to adolescence, whereas those for boys decreased. Female children exposed to maternal depressive symptoms T1 continued to show negative effects 4 years later.     

Overweight, weight concerns, and bulimic behaviors among girls and boys.

OBJECTIVE: To assess the prevalence rates and correlates of overweight, concern with weight, and bulimic behaviors. METHOD: A survey was completed by a population-based sample of 16,114 boys and girls aged 9 to 14 years. RESULTS: Although fewer girls (19%) than boys (26%) were overweight, more girls (25% versus 22%) perceived themselves as overweight (p < .001). The proportion of girls reporting trying to lose weight increased with age (p < .001). The prevalence of binge eating at least monthly increased with age among the girls, but remained stable among the boys. The prevalence of purging was low (< or = 1%) and comparable between genders until age 13. Among the 13- and 14-year-olds, girls were significantly more likely than boys to report using laxatives or vomiting to control weight (p < or = .001). Purging was independently positively associated with stage of pubertal development (girls: odds ratio [OR] = 2.1, 95% confidence interval [CI] 1.6-2.7; boys: OR = 1.5, 95% CI 1.0-2.2) and overweight (girls: OR = 1.9, 95% CI 1.2-3.0; boys: OR = 2.7, 95% CI 1.4-5.1). CONCLUSIONS: Misperception of being overweight and concern with weight were common. Purging was a very rare behavior, but increased with pubertal development. Among the girls, the prevalence increased sharply around the onset of adolescence.     

Abnormalities in MRI-measured signal intensity in the corpus callosum in schizophrenia

The microstructural integrity of the corpus callosum (CC) in first-episode schizophrenia patients was assessed by measuring the signal intensity (SI) in T1-weighted MRI images. Analyses revealed that compared to both healthy controls and non-schizophrenic patients, schizophrenia patients showed reductions in SI in all the callosal subregions, the genu, body, isthmus and splenium in first-episode schizophrenia. These results indicate that schizophrenia is characterized by pathology of this principal interhemispheric commissure; the abnormalities may reflect distributed (rather than localized) interhemispheric disconnectivity that extends beyond the heteromodal association cortices.     

Brain maturation may be arrested in chronic cocaine addicts.

BACKGROUND: Animal and human newborn studies suggest that exposure to cocaine in utero delays glial maturation and white matter myelination. Postmortem data show that in the frontal and temporal lobes, white matter myelination continues into middle age. Recent magnetic resonance imaging (MRI) data have confirmed continued white matter volume increase in these regions, reaching a maximum at age 47. METHODS: Thirty-seven male cocaine dependent (CD) and 52 normal control subjects between ages 19 and 47 were evaluated with MRI. Coronal images focused on the frontal and temporal lobes were acquired using pulse sequences that maximized gray/white matter contrast. RESULTS: Highly significant positive correlations between white matter volume and age were observed in both the frontal and temporal lobes of the control group (r =.52, p =.0001 and r =.54, p =.0001, respectively); however, CD subjects did not demonstrate any age-related increase in white matter volume of the frontal (r = -.001; p =.99) and temporal (r = -.07; p =.67) lobes in this age range. CONCLUSIONS: The age-related expansion in white matter volume occurring in normal control subjects was absent in CD subjects. The findings suggest that in adults, cocaine dependence may arrest normal white matter maturation in the frontal and temporal lobes of addicts who continue using cocaine.     

Hemispheric lateralization of language in epileptic right-handed children with unihemispheric discharge

The epileptic discharge of one hemisphere interferes with brain function. The present study assesses the linguistic disabilities of epileptic patients owing to discharge in one hemisphere. Subjects were classified by age and gender. A significant deterioration of linguistic abilities appeared in adult subjects discharging in the left hemisphere. In children, however, a more symmetric hemispheric pattern of epileptic discharge interference appears with age up to 14 years. Unihemispheric epileptic discharges could also provide information about the degree of lateralization that a given function presents in different developmental stages. This lateralization appears clearly established from the age of 14 to 21 years until late adulthood. These results imply that hemispheric specialization of language is not completed until adolescence. This absence of hemispheric specialization for language in childhood was statistically more significant in boys than in girls, suggesting that the maturation of cortical areas related to language occurs earlier in girls than in boys. Finally, the familial history of left-handedness is a factor delaying the age of left lateralization of language in right-handed children.     

Transient lesion in the splenium of the corpus callosum in acute cerebellitis

We report the reversible magnetic resonance imaging (MRI) findings in a 2-year-old girl with acute cerebellitis. The high signal intensity in the cerebellum was obvious on diffusion-weighted images, and the splenium of the corpus callosum also showed high signal intensity on T2-weighted images and on diffusion-weighted images. The lesion in the splenium quickly returned to normal 72 hours later, whereas the hyperintensity in the cerebellum persisted for 1 week until clinical improvement was achieved. The findings in our patient suggested the particular vulnerability of the splenium of the corpus callosum compared to other regions and the importance of the MRI examinations including diffusion-weighted images in the early stage of encephalitis.     

Childhood head injury and expression of schizophrenia in multiply affected families

BACKGROUND: The etiology of schizophrenia is believed to include genetic and nongenetic factors, with the pathogenesis involving abnormal neurodevelopment. We investigated whether mild head injury during brain maturation plays a role in the expression of schizophrenia in multiply affected families. METHODS: We compared the history and severity of head injuries in childhood (age, < or =10 years) and through adolescence (age, < or =17 years) in 67 subjects with narrowly defined schizophrenia and 102 of their unaffected siblings from 23 multiply affected families. In subjects with schizophrenia, only head injuries preceding the onset of psychosis were considered. RESULTS: Subjects in the schizophrenia group (n = 16 [23.9%]) were more likely than the unaffected siblings group (n = 12 [11.8%]) to have a history of childhood head injury (P =.04; odds ratio, 2.35 [95% confidence interval, 1.03-5.36]). Subjects in the schizophrenia group with a history of childhood head injury had a significantly younger median age at onset of psychosis (20 years) compared with those with no such history (25 years; z = -2.98; P =.003). The severity of head injury ranged from minimal to mild, including concussions, but within this narrow range, severity was correlated with younger age at onset (r(s) = -0.66; P =.005). Head injury occurred a median of 12 years before the onset of psychosis. Results were similar if head injuries during adolescence were included, but did not achieve statistical significance. CONCLUSIONS: Mild childhood head injury may play a role in the expression of schizophrenia in families with a strong genetic predisposition. Prospective studies of mild head injury should consider genetic predisposition for possible long-term neurobehavioral sequelae.