Genetic correlations between brain volumes and the WAIS-III dimensions of verbal comprehension, working memory, perceptual organization, and processing speed

We recently showed that the correlation of gray and white matter volume with full scale IQ and the Working Memory dimension are completely mediated by common genetic factors (Posthuma et al., 2002). Here we examine whether the other WAIS III dimensions (Verbal Comprehension, Perceptual Organization, Processing Speed) are also related to gray and white matter volume, and whether any of the dimensions are related to cerebellar volume. Two overlapping samples provided 135 subjects from 60 extended twin families for whom both MRI scans and WAIS III data were available. All three brain volumes are related to Working Memory capacity (r = 0.27). This phenotypic correlation is completely due to a common underlying genetic factor. Processing Speed was genetically related to white matter volume (

Multivariate genetic analysis of brain structure in an extended twin design

The hunt for genes influencing behavior may be aided by the study of intermediate phenotypes for several reasons. First, intermediate phenotypes may be influenced by only a few genes, which facilitates their detection. Second, many intermediate phenotypes can be measured on a continuous quantitative scale and thus can be assessed in affected and unaffected individuals. Continuous measures increase the statistical power to detect genetic effects (Neale et al., 1994), and allow studies to be designed to collect data from informative subjects such as extreme concordant or discordant pairs. Intermediate phenotypes for discrete traits, such as psychiatric disorders, can be neurotransmitter levels, brain function, or structure. In this paper we conduct a multivariate analysis of data from 111 twin pairs and 34 additional siblings on cerebellar volume, intracranial space, and body height. The analysis is carried out on the raw data and specifies a model for the mean and the covariance structure. Results suggest that cerebellar volume and intracranial space vary with age and sex. Brain volumes tend to decrease slightly with age, and males generally have a larger brain volume than females. The remaining phenotypic variance of cerebellar volume is largely genetic (88%). These genetic factors partly overlap with the genetic factors that explain variance in intracranial space and body height. The applied method is presented as a general approach for the analysis of intermediate phenotypes in which the effects of correlated variables on the observed scores are modeled through multivariate analysis

The integration of faith at work: a contextualized Bible study with Christians at Telekom

https://place.asburyseminary.edu/ecommonsatsdissertations/1655/thumbnail.jp

Insecure attachment during infancy predicts greater amygdala volumes in early adulthood

Background The quality of the early environment is hypothesized to be an influence on morphological development in key neural areas related to affective responding, but direct evidence to support this possibility is limited. In a 22-year longitudinal study, we examined hippocampal and amygdala volumes in adulthood in relation to early infant attachment status, an important indicator of the quality of the early caregiving environment. Methods Participants (N = 59) were derived from a prospective longitudinal study of the impact of maternal postnatal depression on child development. Infant attachment status (24 Secure; 35 Insecure) was observed at 18 months of age, and MRI assessments were completed at 22 years. Results In line with hypotheses, insecure versus secure infant attachment status was associated with larger amygdala volumes in young adults, an effect that was not accounted for by maternal depression history. We did not find early infant attachment status to predict hippocampal volumes. Conclusions Common variations in the quality of early environment are associated with gross alterations in amygdala morphology in the adult brain. Further research is required to establish the neural changes that underpin the volumetric differences reported here, and any functional implications

Association between a longer duration of illness, age and lower frontal lobe grey matter volume in schizophrenia

The frontal lobe has an extended maturation period and may be vulnerable to the long-term effects of schizophrenia. We tested this hypothesis by studying the relationship between duration of illness (DoI), grey matter (GM) and cerebro-spinal fluid (CSF) volume across the whole brain. Sixty-four patients with schizophrenia and 25 healthy controls underwent structural MRI scanning and neuropsychological assessment. We performed regression analyses in patients to examine the relationship between DoI and GM and CSF volumes across the whole brain, and correlations in controls between age and GM or CSF volume of the regions where GM or CSF volumes were associated with DoI in patients. Correlations were also performed between GM volume in the regions associated with DoI and neuropsychological performance. A longer DoI was associated with lower GM volume in the left dorsomedial prefrontal cortex (PFC), right middle frontal cortex, left fusiform gyrus (FG) and left cerebellum (lobule III). Additionally, age was inversely associated with GM volume in the left dorsomedial PFC in patients, and in the left FG and CSF excess near the left cerebellum in healthy controls. Greater GM volume in the left dorsomedial PFC was associated with better working memory, attention and psychomotor speed in patients. Our findings suggest that the right middle frontal cortex is particularly vulnerable to the long-term effect of schizophrenia illness whereas the dorsomedial PFC, FG and cerebellum are affected by both a long DoI and aging. The effect of illness chronicity on GM volume in the left dorsomedial PFC may be extended to brain structure–neuropsychological function relationships

The Danish 22q11 research initiative

Background: Neurodevelopmental brain disorders such as schizophrenia, autism and attention deficit hyperactivity disorder are complex disorders with heterogeneous etiologies. Schizophrenia and autism are difficult to treat and often cause major individual suffering largely owing to our limited understanding of the disease biology. Thus our understanding of the biological pathogenesis needs to be substantiated to enable development of more targeted treatment options with improved efficacy. Insights into the pre-morbid disease dynamics, the morbid condition and the underlying biological disease mechanisms may come from studies of subjects with homogenous etiologies. Breakthroughs in psychiatric genetics have shown that several genetic anomalies predispose for neurodevelopmental brain disorders. We have established a Danish research initiative to study the common microdeletion at chromosome 22q11.2, which is one of the genetic anomalies that confer high risk of schizophrenia, autism and attention deficit hyperactivity disorder. Methods/design: The study applies a "cause-to-outcome" strategy to identify pre-morbid pathogenesis and underlying biological disease mechanisms of psychosis and secondarily the morbid condition of autism and attention deficit hyperactivity disorder. We use a population based epidemiological design to inform on disease prevalence, environmental risk factors and familial disposition for mental health disorders and a case control study design to map the functional effects across behavioral and neurophysiological traits of the 22q11 deletion in a recruited sample of Danish individuals. Discussion: Identification of predictive pre-morbid clinical, cognitive, functional and structural brain alterations in 22q11 deletion carriers may alter current clinical practice from symptomatic therapy of manifest mental illness into early intervention strategies, which may also be applicable to at risk subjects without known etiology. Hopefully new insights into the biological disease mechanisms, which are mandatory for novel drug developments, can improve the outcome of the pharmacological interventions in psychiatry

The effects of an ergonomic chinrest among professional violin players. A biomechanical investigation in a randomised crossover design

This study aimed to compare violinists' upper body kinematics and muscle activity while playing with different supportive equipment: their usual chinrest (UC) or an ergonomic chinrest (EC), each mounted on the violin. Three-dimensional motion capture and electromyographic data were acquired from the upper body while 38 pain-free professional violinists performed an excerpt of a music piece. There were only minor differences between the two set-ups tested. The EC resulted in less left rotation of the head (3.3°), slightly more neck extension (1.3°) and less muscle activity (0.5–1.0 %MVE). However, the overall high static muscle activity (4–10 %MVE across all muscles) was maintained using EC. For both setups, the head posture was left-rotated >15°, ≤6° flexed and left-bent 90% of the time. The EC did not produce a substantial difference in biomechanical load. Instead, future studies may focus on aspects other than chinrest design to lower the static workload demands

Does having a twin-brother make for a bigger brain?

Objective: Brain volume of boys is larger than that of girls by ∼10%. Prenatal exposure to testosterone has been suggested in the masculinization of the brain. For example, in litter-bearing mammals intrauterine position increases prenatal testosterone exposure through adjacent male fetuses, resulting in masculinization of brain morphology. Design: The influence of intrauterine presence of a male co-twin on masculinization of human brain volume was studied in 9-year old twins. Methods: Magnetic resonance imaging brain scans, current testosterone, and estradiol levels were acquired from four groups of dizygotic (DZ) twins: boys from same-sex twin-pairs (SSM), boys from opposite-sex twin-pairs (OSM), girls from opposite-sex twin-pairs (OSF), and girls from same-sex twin-pairs (SSF; n=119 individuals). Data on total brain, cerebellum, gray and white matter volumes were examined. Results: Irrespective of their own sex, children with a male co-twin as compared to children with a female co-twin had larger total brain (+2.5%) and cerebellum (+5.5%) volumes. SSM, purportedly exposed to the highest prenatal testosterone levels, were found to have the largest volumes, followed by OSM, OSF and SSF children. Birth weight partly explained the effect on brain volumes. Current testosterone and estradiol levels did not account for the volumetric brain differences. However, the effects observed in children did not replicate in adult twins. Conclusions: Our study indicates that sharing the uterus with a DZ twin brother increases total brain volume in 9-year olds. The effect may be transient and limited to a critical period in childhood. © 2009 European Society of Endocrinology

Physical workload on neck and shoulder muscles during military helicopter flight - a need for exercise training?

Introduction Work-related neck/shoulder pain is a common complaint among military helicopter pilots and crew members. The flight helmet and additional Night Vision Goggles (NVG) place a considerable load on the cervical spine. The aim of this study was to quantify the physical workload on neck/shoulder muscles to assess possible overload that may call for exercise training to improve capacity and prevent neck pain. Methods Nine pilots and nine crew members from the Royal Danish Air Force participated in a standardized representative flight sortie encompassing: Patient transportation (A-B flight) and Search and Rescue (SAR flight). A standard helmet was used (1.85 kg). SAR flight was performed with NVG (1.1 kg) and A-B flight was performed +/- NVG. Before take-off, one pilot and one crew member were equipped with 6 wireless electromyography (EMG) sensors bilaterally above m. trapezius (TRA), upper neck extensors (UNE) and m. sternocleidomastoideus (SCM). Maximal Voluntary Isometric Contractions (MVC) was performed for normalization. A modified version of the observational method “Posture Activity Tools and Handling” (PATH) was used for assessing work positions during flights. For every minute, the head position of pilots/crew members were classified as: anatomically neutral (&lt;30° flexed), flexed (&gt;30°), extended (&gt;30°), rotated (&gt;30°) and/or laterally flexed (&gt;30°). Results Mean measuring time was for A-B flight: 16.9 ± 5.1 min, for A-B flight + NVG: 22.7 ± 10.8 and for SAR flight: 21.3 ± 11.1. The mean muscle activity in % MVC was highest during SAR flight: pilots 2.9 ± 1.7 (TRA) 12.7 ± 5.2 (UNE) 4.3 ± 2.9 (SCM), Crew members 4.1 ± 3.8 (TRA) 10.5 ± 2.4 (UNE) 2.4 ± 1.5 (SCM). Muscle activity in UNE was significantly higher than in TRA and SCM during all flights, except for crew members when compared to TRA during A-B flight (P = 0.086). For crew members muscle activity in UNE was significantly higher during A-B flight + NVG compared to - NVG (P = 0.021), while no significant difference was found for pilots. Non-neutral head positions in % of SAR flight time were for pilots observed for 88.6% (flexed) and 64.4% (rotated), and for crew members for 93.8% (flexed) and 89.9% (rotated). Discussion The mean muscle activity during flights was overall ~ 10% MVC in UNE and even higher during SAR flight, which is considered a high sustained activity level. Such high workload in combination with the flexed and/or rotated positioning of the head may play a role for the high prevalence of neck/shoulder pain among this occupational group. The present exposure-assessment suggests that strengthening exercises for the UNE, lowering the relative load during flights, could potentially alleviate neck pain. <br/

Physical workload on neck and shoulder muscles during military helicopter flight - a need for exercise training?

Introduction Work-related neck/shoulder pain is a common complaint among military helicopter pilots and crew members. The flight helmet and additional Night Vision Goggles (NVG) place a considerable load on the cervical spine. The aim of this study was to quantify the physical workload on neck/shoulder muscles to assess possible overload that may call for exercise training to improve capacity and prevent neck pain. Methods Nine pilots and nine crew members from the Royal Danish Air Force participated in a standardized representative flight sortie encompassing: Patient transportation (A-B flight) and Search and Rescue (SAR flight). A standard helmet was used (1.85 kg). SAR flight was performed with NVG (1.1 kg) and A-B flight was performed +/- NVG. Before take-off, one pilot and one crew member were equipped with 6 wireless electromyography (EMG) sensors bilaterally above m. trapezius (TRA), upper neck extensors (UNE) and m. sternocleidomastoideus (SCM). Maximal Voluntary Isometric Contractions (MVC) was performed for normalization. A modified version of the observational method “Posture Activity Tools and Handling” (PATH) was used for assessing work positions during flights. For every minute, the head position of pilots/crew members were classified as: anatomically neutral (&lt;30° flexed), flexed (&gt;30°), extended (&gt;30°), rotated (&gt;30°) and/or laterally flexed (&gt;30°). Results Mean measuring time was for A-B flight: 16.9 ± 5.1 min, for A-B flight + NVG: 22.7 ± 10.8 and for SAR flight: 21.3 ± 11.1. The mean muscle activity in % MVC was highest during SAR flight: pilots 2.9 ± 1.7 (TRA) 12.7 ± 5.2 (UNE) 4.3 ± 2.9 (SCM), Crew members 4.1 ± 3.8 (TRA) 10.5 ± 2.4 (UNE) 2.4 ± 1.5 (SCM). Muscle activity in UNE was significantly higher than in TRA and SCM during all flights, except for crew members when compared to TRA during A-B flight (P = 0.086). For crew members muscle activity in UNE was significantly higher during A-B flight + NVG compared to - NVG (P = 0.021), while no significant difference was found for pilots. Non-neutral head positions in % of SAR flight time were for pilots observed for 88.6% (flexed) and 64.4% (rotated), and for crew members for 93.8% (flexed) and 89.9% (rotated). Discussion The mean muscle activity during flights was overall ~ 10% MVC in UNE and even higher during SAR flight, which is considered a high sustained activity level. Such high workload in combination with the flexed and/or rotated positioning of the head may play a role for the high prevalence of neck/shoulder pain among this occupational group. The present exposure-assessment suggests that strengthening exercises for the UNE, lowering the relative load during flights, could potentially alleviate neck pain. <br/