Biomedical subjects

Allan L Reiss

Publications and source records attributed to Allan L Reiss.

At least 19 recordsLinked to original sources

PubMed2003

Effects of X-monosomy and X-linked imprinting on superior temporal gyrus morphology in Turner syndrome.

BACKGROUND: Turner syndrome (TS) results from complete or partial monosomy X. The cognitive phenotype of TS involves preservation of verbal skills with visuospatial functioning deficits. The superior temporal gyrus (STG), which is involved in language capacities, has not been investigated in TS. METHODS: The STG was measured in 30 female subjects (mean age = 14.73 +/- 6.41; range = 7.56-33.30) with TS and 30 age-matched control subjects (mean age = 14.63 +/- 5.90; range = 6.35-32.65) using volumetric magnetic resonance imaging analyses. RESULTS: -Right STG, including both gray and white matter volumes, was significantly larger in TS compared with control subjects. Overall left STG volume was not significantly different between groups, although left white matter volume was increased in the TS subjects. The TS subgroup with a maternally derived X chromosome (Xm) demonstrated more aberrant STG volumes compared with subjects with a paternally (Xp) derived X and control subjects. The difference in STG volumes between Xm and control subjects involved both white and gray matter. The Xm subjects differed from Xp subjects only in terms of gray matter. CONCLUSIONS: These findings suggest that X-monosomy and X-linked imprinting negatively affect STG development, possibly by disrupting neural pruning mechanisms.

Adolescent↗

PubMed2003

White matter tract alterations in fragile X syndrome: preliminary evidence from diffusion tensor imaging.

Fragile X syndrome, the most common form of hereditary mental retardation, causes disruption in the development of dendrites and synapses, the targets for axonal growth in the central nervous system. This disruption could potentially affect the development, wiring, and targeting of axons. The current study utilized diffusion tensor imaging (DTI) to investigate whether white matter tract integrity and connectivity are altered in fragile X syndrome. Ten females with a diagnosis of fragile X syndrome and ten, age matched, female control subjects underwent diffusion weighted MRI scans. A whole brain analysis of fractional anisotropy (FA) values was performed using statistical parametric mapping (SPM). A follow-up, regions-of-interest analysis also was conducted. Relative to controls, females with fragile X exhibited lower FA values in white matter in fronto-striatal pathways, as well as in parietal sensory-motor tracts. This preliminary study suggests that regionally specific alterations of white matter integrity occur in females with fragile X. Aberrant white matter connectivity in these regions is consistent with the profile of cognitive and behavioral features of fragile X syndrome, and potentially provide additional insight into the detrimental effects of suboptimal levels of FMRP in the developing brain.

Adolescent↗

PubMed2003

Abnormal prefrontal cortex function during response inhibition in Turner syndrome: functional magnetic resonance imaging evidence.

BACKGROUND: Turner syndrome (TuS) arises from the partial or complete absence of one X chromosome. Although neuropsychological studies report impaired attentional function and response inhibition in TuS, the neural correlates of these cognitive problems are unknown. METHODS: Eleven female subjects with TuS and 11 individually matched normal control subjects were imaged using functional magnetic resonance imaging while performing a Go/NoGo task. RESULTS: Groups did not differ on accuracy or reaction time; however, the TuS group activated more in the bilateral superior and middle frontal gyri than control subjects. Control subjects did not activate more than the TuS group in any region. CONCLUSION: These findings suggest that female subjects with TuS compensate for executive dysfunction via recruitment of additional prefrontal cortex regions involved in inhibition, attention, and working memory, functions necessary for successful performance of Go/NoGo tasks. Elucidating brain function in TuS will advance our understanding of the influence of X-chromosome genes on neurodevelopment and brain function and contribute to planning future intervention strategies.

Adolescent↗

PubMed2003

Regional analysis of hippocampal activation during memory encoding and retrieval: fMRI study.

Investigators have recently begun to examine the differential role of subregions of the hippocampus in episodic memory. Two distinct models have gained prominence in the field. One model, outlined by Moser and Moser (Hippocampus 1998;8:608-619), based mainly on animal studies, has proposed that episodic memory is subserved by the posterior two-thirds of the hippocampus alone. A second model, derived by Lepage et al. (Hippocampus 1998;8:313-322) from their review of 52 PET studies, has suggested that the anterior hippocampus is activated by memory encoding while the posterior hippocampus is activated by memory retrieval. Functional magnetic resonance imaging (fMRI) studies have tended to show limited activation in the anteriormost regions of the hippocampus, providing support for the Moser and Moser model. A potential confounding factor in these fMRI studies, however, is that susceptibility artifact may differentially reduce signal in the anterior versus the posterior hippocampus. In the present study, we examined activation differences between hippocampal subregions during encoding and retrieval of words and interpreted our findings within the context of these two models. We also examined the extent to which susceptibility artifact affects the analysis and interpretation of hippocampal activation by demonstrating its differential effect on the anterior versus the posterior hippocampus. Both voxel-by-voxel and region-of-interest analyses were conducted, allowing us to quantify differences between the anterior and posterior aspects of the hippocampus. We detected significant hippocampal activation in both the encoding and retrieval conditions. Our data do not provide evidence for regional anatomic differences in activation between encoding and retrieval. The data do suggest that, even after accounting for susceptibility artifact, both encoding and retrieval of verbal stimuli activate the middle and posterior hippocampus more strongly than the anterior hippocampus. Finally, this study is the first to quantify the effects of susceptibility-induced signal loss on hippocampal activation and suggests that this artifact has significantly biased the interpretation of earlier fMRI studies.

Adolescent↗

PubMed2003

Neural correlates of auditory perception in Williams syndrome: an fMRI study.

Williams syndrome (WS), a neurogenetic developmental disorder, is characterized by a rare fractionation of higher cortical functioning: selective preservation of certain complex faculties (language, music, face processing, and sociability) in contrast to marked and severe deficits in nearly every other cognitive domain (reasoning, spatial ability, motor coordination, arithmetic, problem solving). WS people are also known to suffer from hyperacusis and to experience heightened emotional reactions to music and certain classes of noise. We used functional magnetic resonance imaging to examine the neural basis of auditory processing of music and noise in WS patients and age-matched controls and found strikingly different patterns of neural organization between the groups. Those regions supporting music and noise processing in normal subjects were found not to be consistently activated in the WS participants (e.g., superior temporal and middle temporal gyri). Instead, the WS participants showed significantly reduced activation in the temporal lobes coupled with significantly greater activation in the right amygdala. In addition, WS participants (but not controls) showed a widely distributed network of activation in cortical and subcortical structures, including the brain stem, during music processing. Taken together with previous ERP and cytoarchitectonic studies, this first published report of WS using fMRI provides additional evidence of a different neurofunctional organization in WS people than normal people, which may help to explain their atypical reactions to sound. These results constitute an important first step in drawing out the links between genes, brain, cognition, and behavior in Williams syndrome.

Adolescent↗

PubMed2003

Corpus callosum and posterior fossa development in monozygotic females: a morphometric MRI study of Turner syndrome.

Previous neuroimaging research in Turner syndrome (TS) has indicated parietal lobe anomalies, while anomalies in other brain loci have been less well-substantiated. This study focused on potential cerebellar abnormalities and possible disruptions of interhemispheric (parietal) callosal connections in individuals with TS. Twenty-seven female children and adolescents with TS (mean age 13 years, SD 4 years 2 months) and 27 age-matched female control individuals (mean age 13 years 2 months, SD 4 years 1 month) underwent MRI. Age range of all participants was 7 to 20 years. Morphometric analyses of midline brain structures were conducted using standardized, reliable methods. When compared with control participants, females with TS showed reduced areas of the genu of the corpus callosum, the pons, and vermis lobules VI-VII, and an increased area of the fourth ventricle. No group difference in intracranial area measurements was observed. The reduced area of the genu in TS may reflect compromised connectivity between inferior parietal regions. Further, cerebellar vermis hypoplasia associated with TS agrees with literature that suggests the posterior fossa as a region prone to structural alterations in the face of early developmental insult.

Adolescent↗

PubMed2003

Factors associated with parenting stress in mothers of children with fragile X syndrome.

Whereas previous research has demonstrated elevated levels of parenting stress in parents of children with general developmental disability, there has been little investigation of stress in parents of children specifically affected by the common neurogenetic disorder fragile X syndrome (FraX). This study elucidates stress profiles in mothers of children with FraX and delineates the contribution of child characteristics, home environment, and maternal psychological functioning to specific dimensions of parental stress. Data on child, home, and family characteristics were collected from 75 families with a child affected by FraX. These characteristics were entered into multiple regression analyses with a domain or subscale of the Parenting Stress Index as the dependent variable in each analysis. The results demonstrated that aspects of child behavior, family cohesion, household income, and maternal psychopathology differentially correlate with specific dimensions of parenting stress. Determining the relative contribution of factors associated with stress will assist in the development of interventions to improve parental well-being in mothers of children with FraX.

Adolescent↗

PubMed2003

Amygdalar activation associated with happy facial expressions in adolescents: a 3-T functional MRI study.

OBJECTIVE: To study the possible role of the amygdala in the recognition of happy and sad facial expressions in adolescents aged 13 to 17 years. METHOD: Twelve healthy adolescents (6 females and 6 males) underwent noninvasive 3-Tesla functional magnetic resonance imaging while viewing pictures of happy, sad, and neutral facial expressions. RESULTS: Happy faces produced significant bilateral amygdalar activation when compared with neutral faces (p <.05, corrected). Sad faces relative to neutral did not produce significant amygdalar activation. CONCLUSIONS: These results extend the role of the amygdala in adolescents to include the recognition of happy facial expressions. They demonstrate the feasibility of using happy facial expressions to noninvasively study amygdalar function in adolescents and establish a baseline against which the amygdalar response to emotional stimuli in several psychiatric conditions may be compared.

Adolescent↗

PubMed2003

A prospective test of the association between hyperarousal and emotional numbing in youth with a history of traumatic stress.

Investigated the hypothesis that emotional numbing may develop as a result of hyperarousal using a prospective design. Forty-two children between the ages of 7 and 14 with a history of trauma and posttraumatic stress disorder (PTSD) symptoms were assessed with the Clinician-Administered PTSD Scale for Children and Adolescents (CAPS-CA; Nader et al., 1996) and were reassessed 1 year later. Results indicated that hyperarousal symptoms were concurrently positively correlated with emotional numbing at both time points. Moreover, Time 1 hyperarousal symptoms were associated with emotional numbing at Time 2 and predicted Time 2 emotional numbing even when controlling for each of the other symptom clusters of PTSD at Time 1 as well as other concurrent (i.e., Time 2) PTSD symptoms. Results are discussed in terms of the implications of the findings for enhancing the understanding of PTSD symptoms in youth.

Affective Symptoms↗

PubMed2002

Brain development in Turner syndrome: a magnetic resonance imaging study.

Turner syndrome (TS) results from the absence of an X chromosome in females. This genetic condition is associated with specific cognitive deficits and variations in brain volumes. The goal of this study was to use high-resolution magnetic resonance imaging (MRI) to determine morphological variations in TS and to investigate the effects of parental origin of the X chromosome on brain development in TS. MRI brain scans were acquired from 26 girls with TS and 26 age- and gender-matched controls. Seventeen of the TS subjects had a maternally inherited X chromosome (Xm), and nine of the subjects had a paternally inherited X chromosome (Xp). Rater-blind morphometric analyses were conducted to compare tissue volume differences between girls with TS and controls. Three-way analyses were used to compare subgroups and controls. Subjects with TS demonstrated bilateral decreases in parietal gray and occipital white matter accompanied by increased cerebellar gray matter. Subjects with Xm showed decreased occipital white matter and increased cerebellar gray matter compared to controls. No differences were found in comparisons between subjects with Xp and controls or between subjects with Xm and Xp. Results suggest that X monosomy affects posterior cerebral and cerebellar anatomy in TS. While differences between comparisons of Xm and Xp to controls might suggest an imprinting effect, no significant differences were found when the two subgroups were directly compared to each other. Further investigation into the possible role of genomic imprinting is therefore warranted.

Adolescent↗

PubMed2002

Functional connectivity in the resting brain: a network analysis of the default mode hypothesis.

Functional imaging studies have shown that certain brain regions, including posterior cingulate cortex (PCC) and ventral anterior cingulate cortex (vACC), consistently show greater activity during resting states than during cognitive tasks. This finding led to the hypothesis that these regions constitute a network supporting a default mode of brain function. In this study, we investigate three questions pertaining to this hypothesis: Does such a resting-state network exist in the human brain? Is it modulated during simple sensory processing? How is it modulated during cognitive processing? To address these questions, we defined PCC and vACC regions that showed decreased activity during a cognitive (working memory) task, then examined their functional connectivity during rest. PCC was strongly coupled with vACC and several other brain regions implicated in the default mode network. Next, we examined the functional connectivity of PCC and vACC during a visual processing task and show that the resultant connectivity maps are virtually identical to those obtained during rest. Last, we defined three lateral prefrontal regions showing increased activity during the cognitive task and examined their resting-state connectivity. We report significant inverse correlations among all three lateral prefrontal regions and PCC, suggesting a mechanism for attenuation of default mode network activity during cognitive processing. This study constitutes, to our knowledge, the first resting-state connectivity analysis of the default mode and provides the most compelling evidence to date for the existence of a cohesive default mode network. Our findings also provide insight into how this network is modulated by task demands and what functions it might subserve.

Adult↗

PubMed2002

Amygdalar activation associated with positive and negative facial expressions.

Most theories of amygdalar function have underscored its role in fear. One broader theory suggests that neuronal activation of the amygdala in response to fear-related stimuli represents only a portion of its more widespread role in modulating an organism's vigilance level. To further explore this theory, the amygdalar response to happy, sad, angry, fearful, and neutral faces in 17 subjects was characterized using 3 T fMRI. Utilizing a random effects model and hypothesis-driven analytic strategy, it was observed that each of the four emotional faces was associated with reliable bilateral activation of the amygdala compared with neutral. These findings suggest a broader role for the amygdala in modulating the vigilance level during the perception of several negative and positive facial emotions.

Adolescent↗

PubMed2002

Future of genetics of mood disorders research.

This report summarizes the deliberations of a panel with representation from diverse disciplines of relevance to the genetics of mood disorders. The major charge to the panel was to develop a strategic plan to employ the tools of genetics to advance the understanding, treatment, and outcomes for mood disorders. A comprehensive review of the evidence for the role of genetic factors in the etiology of mood disorders was conducted, and the chief impediments for progress in gene identification were identified. The National Institute of Mental Health (NIMH) portfolios in the Genetics Research Branch and the Division of Mental Disorders, Behavioral Sciences, AIDS, and all genetics training activities were reviewed. Despite some promising leads, there are still no confirmed linkage findings for mood disorders. Impediments to gene finding include the lack of phenotypic validity, variation in ascertainment sources and methodology across studies, and genetic complexity. With respect to linkage, the committee recommended that a large-scale, integrated effort be undertaken to examine existing data from linkage and association studies of bipolar disorders using identical phenotypes and statistical methods across studies to determine whether the suggestive linkage findings at some loci can be confirmed. Confirmation would justify more intensive approaches to gene finding. The committee recommended that the NIMH support continued efforts to identify the most heritable subtypes and endophenotypes of major depression using the tools of genetic epidemiology, neuroscience, and behavioral science. The field of genetic epidemiology was identified as an important future direction because population-based, epidemiologic studies of families and unrelated affected individuals assume increasing importance for common chronic diseases. To prepare for shifts to more complex genetic models, the committee recommended that the NIMH develop new interdisciplinary training strategies to prepare for the next generation of genetics research.

Genetic Linkage↗

PubMed2002

Increased basal ganglia volumes in velo-cardio-facial syndrome (deletion 22q11.2).

BACKGROUND: This study evaluated differences in caudate volumes in subjects with velo-cardio-facial syndrome due to a 22q11.2 (22qDS) deletion. Because psychosis is observed in 30% of adult subjects with 22qDS, this neurogenetic disorder could represent a putative model for a genetically mediated subtype of schizophrenia. METHODS: Caudate volumes were measured on high-resolution magnetic resonance images in 30 children and adolescents with 22qDS and 30 gender- and age-matched normal comparison subjects. RESULTS: Caudate head volumes were increased in the 22qDS group independent of neuroleptic medications. Subjects with 22qDS also displayed an abnormal pattern of asymmetry in the anterior caudate, with left side greater than right. CONCLUSIONS: Alterations in the basal ganglia circuitry have been implicated in learning, cognitive, and behavioral problems in children and therefore could be involved in the expression of the neurobehavioral phenotype expressed by subjects with 22qDS. Abnormal caudate volume is a neurodevelopmental feature shared with schizophrenia, further establishing 22qDS as a potential neurodevelopmental model for this disorder.

Adolescent↗

PubMed2002

Diurnal salivary cortisol in pediatric posttraumatic stress disorder.

BACKGROUND: The hypothalamic-pituitary-adrenal (HPA) axis has been implicated in the pathophysiology of posttraumatic stress disorder (PTSD). Additional information on basal cortisol levels in children exposed to trauma and experiencing PTSD symptoms may contribute to the understanding of the role of this axis in PTSD. METHODS: Fifty-one children (30 boys and 21 girls, mean age 10.7 years) with a history of exposure to trauma and PTSD symptoms were compared with 31 age- and gender-matched healthy control subjects. Salivary cortisol was obtained from participants during home measurements and was collected four times a day (prebreakfast, prelunch, predinner, and prebed) for up to 3 consecutive days. RESULTS: The clinical group demonstrated significantly elevated cortisol levels when compared with the control group. In addition, exploratory analyses revealed that girls with PTSD symptoms had significantly elevated cortisol levels when compared with boys with PTSD symptoms. CONCLUSIONS: The physiologic response of children with history of trauma and with PTSD symptoms may be characterized by heightened adrenal activity.

Adolescent↗

PubMed2002

Psychiatric disorders and behavioral problems in children with velocardiofacial syndrome: usefulness as phenotypic indicators of schizophrenia risk.

BACKGROUND: Velocardiofacial syndrome (VCFS), a genetic deletion condition with numerous cognitive sequelae, is associated with a high rate of psychiatric disorders in childhood. More recently, VCFS has been identified as a high-risk factor for developing adult onset schizophrenia. However, it has never been demonstrated that the childhood psychiatric disorders found in children with VCFS differ from those found in children with a similar degree of cognitive impairment. Identification of a specific behavioral (psychiatric) phenotype in childhood VCFS offers the potential for elucidating the symptomatic precursors of adult onset schizophrenia. METHODS: Twenty-eight children with VCFS and 29 age- and cognitively matched control subjects received a standardized assessment of childhood psychiatric disorders and behaviors measured by the Child Behavior Checklist (CBCL). Findings from the two groups were compared. RESULTS: The rates and types of psychiatric disorder and behavior problems in VCFS and cognitively matched control subjects were very high, but showed no significant differences. CONCLUSIONS: Psychopathology in children with VCFS may not differ from that found in cognitively matched control subjects. Another explanation is that subtle phenotypic differences in behavior found in VCFS can not be observed using standard symptom inventories. The high rate of psychopathology in children with VCFS is not a useful phenotypic indicator of high risk for adult onset schizophrenia.

Adolescent↗

PubMed2002

fMRI study of cognitive interference processing in females with fragile X syndrome.

Females with fragile X syndrome, the most common form of inherited developmental and learning problems, are known to be impaired in executive function. The current study is the first to investigate the performance of females with fragile X on a cognitive interference task utilizing functional magnetic resonance imaging (fMRI). Fourteen females with fragile X and 14 age-matched healthy controls were imaged while they performed a counting Stroop interference task. Compared to controls, females with fragile X appeared to have longer reaction times during the interference condition of the task, and adopted a strategy trading speed for accuracy. Females with fragile X also had a significantly different pattern of activation than controls. Whereas controls showed significant activation in the inferior/middle frontal gyrus and inferior/superior parietal lobe, females with fragile X showed more extensive activation in the anterior region of the prefrontal cortex, and failed to show expected activation in the inferior/superior parietal lobe. Further, between-group analyses revealed that females with fragile X had reduced activation in the left orbitofrontal gyrus, thought to be involved in modulating goal-directed behavior. Females with fragile X also demonstrated a markedly different pattern of deactivation from controls. These findings suggest that deficits in cognitive interference processing during the counting Stroop task observed in females with fragile X may arise from inability to appropriately recruit and modulate lateral prefrontal and parietal resources.

Adolescent↗

PubMed2002

Reduced size of the amygdala in individuals with 47,XXY and 47,XXX karyotypes.

The excess of 47,XXX and 47,XXY karyotypes found in cytogenetic screening studies of individuals with schizophrenia has given support for an increased risk of psychiatric illness among men and women with sex chromosomal aneuploidy (SCA). Mesial temporal lobe structures, including the amygdala and hippocampus, are thought to be associated with abnormalities of mood and behavior in humans and in the neurobiology of schizophrenia. This study focuses on variations in volumes of mesial temporal lobe structures in men and women with SCA. Utilizing an unselected birth cohort of subjects with SCA and high-resolution magnetic resonance imaging (MRI), we investigated the neuroanatomical consequences of a supernumerary X chromosome on the morphology of the amygdala and hippocampus. Regional and total brain volumes were measured in 10 subjects with 47,XXY, 10 subjects with 47,XXX, and 20 euploid controls. Amygdala volumes were significantly reduced in men with 47,XXY, compared to control men, while the decrease in women with 47,XXX was not as pronounced. Hippocampus volumes were preserved in both groups, compared to same-gender controls. Longitudinal studies of SCA individuals have shown an increased incidence of mild psychopathology and behavioral dysfunction in men with 47,XXY and more overt psychiatric illness in women with 47,XXX, compared to control populations. The alteration in amygdala volumes in individuals with a supernumerary X chromosome may provide a neuroanatomic basis for these findings.

Adult↗