Brain stem auditory, pattern-reversal visual, and short-latency somatosensory evoked potentials: latencies in relation to age, sex, and brain and body size

To determine standards of normality for auditory, somatosensory and visual evoked potentials commonly used in the assessment of neurological disease, 8 AEP, 1 VEP and 12 SEP components were recorded to stimulation of left and right ears, eyes, and median nerves in 286 normal subjects ranging in age from 4 to 95 years. Peak and interpeak latencies, and left-right differences in latency, were analyzed as a function of age, sex, and estimates of brain and body size. Major features of the results were: (1) Peak latencies of all components showed statistically significant increases in latency with age except that VEP P100 latency decreased significantly between 4 and 19 years and did not change between 20 and 59 years. (2) In adults the peak latencies of all components were significantly later in males than in females. For AEPs and VEPs these differences were explained by sex differences in brain size, and for adult SEPs were explained by sex differences in arm and shoulder dimensions. No significant sex differences in VEP and SEP latencies were seen in children. (3) Most interpeak latencies showed significant differences in relation to age or sex. (4) Age and sex are useful predictors of latency for nearly all peak and interpeak latencies; in addition, height is a useful predictor of SEP peak latencies. (5) Left-right latency differences showed little age-related, and no sex-related, change. The interlaboratory use of these or other normative data was discussed. It was concluded that these AEP and SEP norms can probably be used in other laboratories if stimulating and recording conditions are similar. However, VEP results are difficult to transfer due to the poorly understood effects of variation in stimulus conditions. Some issues regarding the optimal characterization of norms were also discussed.     

Brain size,sex, and the aging brain

This study was conducted to examine the statistical influence of brain size on cortical, subcortical, and cerebellar compartmental volumes. This brain size influence was especially studied to delineate interactions with Sex and Age. Here, we studied 856 healthy subjects of which 533 are classified as young and 323 as old. Using an automated segmentation procedure cortical (gray and white matter [GM and WM] including the corpus callosum), cerebellar (GM and WM), and subcortical (thalamus, putamen, pallidum, caudatus, hippocampus, amygdala, and accumbens) volumes were measured and subjected to statistical analyses. These analyses revealed that brain size and age exert substantial statistical influences on nearly all compartmental volumes. Analyzing the raw compartmental volumes replicated the frequently reported Sex differences in compartmental volumes with men showing larger volumes. However, when statistically controlling for brain size Sex differences and Sex × Age interactions practically disappear. Thus, brain size is more important than Sex in explaining interindividual differences in compartmental volumes. The influence of brain size is discussed in the context of an allometric scaling of the compartmental volumes. Hum Brain Mapp, 36:150–169, 2015. © 2014 Wiley Periodicals, Inc .     

Self-derogation and social position: Interaction effects of sex,race, education,and age

Summary The present study investigates the individual and interaction effects of sex, race, education, and age upon self-derogation. Data were collected by survey research methods from a sample (N=500) of the adult population of Harris County (including the city of Houston), Texas. Self-Derogation was measured by a factorially derived index. The individual effects of the social positions upon self-derogation were generally statistically nonsignificant and/or not uniform throughout the population. However, strong interaction effects were observed. Self-derogation was relatively great among: less educated white females; more educated Negro males; and less educated white males, aged 50–59. It was suggested that systematic consideration of the interaction effects of social positions would account for much of the inconsistency apparent in the related literature and would lead to further hypotheses regarding the genesis of negative self-attitudes.

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Zusammenfassung Die vorliegende Untersuchung befaßt sich mit den individuellen und den miteinander in Beziehung stehenden Einflüssen von Geschlecht, Rasse, Bildung und Alter auf Selbsterniedrigung. Die Erhebung erfolgte über eine systematische Zufallsauswahl einer Stichprobe (N=500) aus der Erwachsenenpopulation von Harris County (einschließlich der Stadt Houston) in Texas. Selbsterniedrigung wurde mittels eines faktorenanalytisch abgeleiteten Index gemessen. Die individuellen Einflüsse von sozialen Positionen auf Selbsterniedrigung waren im allgemeinen statistisch nicht signifikant und/oder nicht einheitlich innerhalb der Bevölkerung. Jedoch wurden starke Interaktionseinflüsse beobachtet. Selbsterniedrigung war relativ ausgeprägt bei weniger gebildeten weißen Frauen, bei besser gebildeten männlichen Negern und bei weniger gebildeten weißen Männern zwischen 50 und 59 Jahren. Es wurde vorgeschlagen, daß die systematische Berücksichtigung der Interaktionswirkung von sozialen Positionen viel von der Widersprüchlichkeit erklären würde, die in der diesbezüglichen Literatur offenbar ist, und zu weiteren Hypothesen hinsichtlich des Ursprungs von negativen Einstellungen zur eigenen Person führen würde.

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Résumé Dans la présente étude, on examine les effets, considérés individuellement et en interaction les uns avec les autres, du sexe, de la race, de l'éducation et de l'âge sur l'attitude négative à l'égard de soi-même. On a recueilli, au moyen des méthodes d'observation de recherche, les données fournies par un échantillon (N=500) de la population adulte de Harris County (comprenant la ville de Houston), Texas. L'attitude négative à l'égard de soi-même a été mesurée selon un index factoriel dérivé. Les effets individuels de la position sociale sur cette attitude négative étaient de façon générale statistiquement non significatifs et/ou non uniformes parmi la population. Par contre, en interaction avec d'autres facteurs, ces effets se sont révélés très prononcés. L'attitude négative à l'égard de soi-même était relativement grande parmi: les femmes blanches moins éduquées; les hommes noirs plus éduqués; et les hommes blancs moins éduqués de 50 à 59 ans. On pense qu'une prise en considération systématique des effets de la position sociale en interaction avec d'autres facteurs comblerait bien des lacunes de la littérature se rapportant à ce sujet et amènerait d'autres hypothèses concernant la genèse des attitudes négatives à l'égard de soi-même.

     

Cerebral lateralization of speech: The effects of age,sex, race,and socioeconomic class

This study attempted to discover what effects the variables of age, sex, race, and socioeconomic class have on ear asymmetry. A significant right ear superiority was found at all ages studied; 5, 7, 9, and 11 yr of age. Males were found to develop essentially the same as females and white children develop the same as black children on dichotic listening tasks, which were utilized as the criteria measures of ear asymmetry. There were significant social class differences found, the middle class S's showing a significantly greater degree of asymmetry than their lower class counterparts. All ages in both social classes, however, showed a significant right-left difference in favor of the right ear. Precise methodological controls were utilized and their relevance discussed. Possible explanations for discrepant findings between the present study and other research are also discussed.     

Cardiac autonomic control and the effects of age, race, and sex: the CARDIA study

BACKGROUND: Stratification variables of age, race, and sex figure prominently in the assessment of cardiovascular disease risk. Similarly, cardiac autonomic regulation, measured by RR interval variability (RRV), is associated with risk. The relationship among these variables is unclear. METHODS: We examined the cross-sectional relationship between RRV and age, race, and sex in 757 subjects from the NHLBI-funded Coronary Artery Disease in Young Adults (CARDIA) Study. RESULTS: Age was a significant determinant of RRV, despite the narrow range (33-47): participants aged 33-39 years had had greater levels of HF power, LF power, and standard deviation (SD) of RR intervals than did those aged 40-47 years. There was no age effect for the LF/HF ratio. Compared to whites, blacks had lower levels of LF power, SD, and lower LF/HF. Blacks and whites did not differ in HF power. Finally, compared to men, women had lower levels of LF power, SD, and LF/HF but did not differ in HF power. CONCLUSIONS: Data from the CARDIA study suggest that in adults in the 33-47 year age range, indices of RRV were greater in younger compared to older subjects, in men compared to women and in whites compared to blacks. These findings are broadly consistent with those of other large studies examining relationships between RRV and age, sex, and race. However, patterns of associations between RRV and these stratification variables are not entirely consistent with an underlying autonomic physiology linked to cardioprotection.     

Correlation of neuronal cell body size in motor cortex and hippocampus with body height, body weight, and axonal length.

This study examined the comparative effects of body height and body weight on the neuronal cell size in humans and investigated their possible mechanisms. A total of 21 cases between the ages of 20 and 40 years were studied. Data on body height, body weight, and neuropathology were obtained from autopsy records. Mean cross sectional areas of cell bodies for 30 normal neurons were determined for the motor cortex projecting to lumbar spinal cord segments (L) 1-4 (Betz cells) as well as various regions of the hippocampus. Approximate axonal length of the motor neuron studied was measured from motor cortex to L2. We found that only motor cortex neuronal cell body size was significantly proportional to body height and the respective axonal length (p < .05). The findings indicate that: 1) body height has a greater effect than body weight on the motor neuron cell size, probably because of its association with axonal length; 2) the effect is regional (motor cortex) rather than general.     

Influence of age,sex and genetic factors on the human brain

We report effects of age, age², sex and additive genetic factors on variability in gray matter thickness, surface area and white matter integrity in 1,010 subjects from the Genetics of Brain Structure and Function Study. Age was more strongly associated with gray matter thickness and fractional anisotropy of water diffusion in white matter tracts, while sex was more strongly associated with gray matter surface area. Widespread heritability of neuroanatomic traits was observed, suggesting that brain structure is under strong genetic control. Furthermore, our findings indicate that neuroimaging-based measurements of cerebral variability are sensitive to genetic mediation. Fundamental studies of genetic influence on the brain will help inform gene discovery initiatives in both clinical and normative samples.     

Aromatase activity in the perinatal rat forebrain: effects of age, sex and intrauterine position

Sex and regional differences in aromatase activity were characterized in brains of rats sacrificed on embryonic days 18 (E18) and 20 (E20) and on postnatal days 2, 4 and 13 (D2, D4, D13). Aromatase activity was measured in vitro in homogenates of the hypothalamus/preoptic area (HPOA) and temporal lobe (TL) from individual rats, using [3H]19-hydroxyandrostenedione as substrate in the presence of NADPH. The apparent Km of aromatase for 19-hydroxyandrostenedione in TL at D4 was similar in males (34 nM) and females (22 nM,). Aromatase activity in the HPOA was highest prenatally (E18) and gradually declined to low levels by D13. Aromatase activity in the TL remained constant from E18 to D2, increased significantly on D4, and subsequently declined to low levels by D13. The level of aromatase activity was significantly greater in males than in females on E18 and D4 in the HPOA and on D4 in the TL. Differences in aromatase activity within regions of the HPOA were studied at E20 and D4. At both ages, the activity was highest in the preoptic area, lower in the anterior hypothalamus (AH), and lowest in the posterior hypothalamus. Aromatase activity was significantly higher in males than in females in the AH, but only on D4. The contiguity of males in utero was not correlated with aromatase activity in brain regions of adjacent female fetuses. The present results indicate that significant sex differences in aromatase activity exist in specific brain regions only at discrete times during perinatal development.(ABSTRACT TRUNCATED AT 250 WORDS)     

Correlation of glial proliferation with age in the mouse brain

Radioautographs of brain sections were prepared after injection of ³H-thymidine into mice aged 23, 100, 200 or 400 days. The presence of a small number of labeled cells in all animals indicates that neuroglia do proliferate even at an advanced age. Proliferation is most active in the corpus callosum and least so in the corpus striatum. Comparison of the counts of labeled and unlabeled nuclei suggests that glial cells are produced in numbers exceeding growth requirements and, accordingly, that they turn over, although slowly.     

Predicting sex,age, general cognition and mental health with machine learning on brain structural connectomes

There is an increasing expectation that advanced, computationally expensive machine learning (ML) techniques, when applied to large population‐wide neuroimaging datasets, will help to uncover key differences in the human brain in health and disease. We take a comprehensive approach to explore how multiple aspects of brain structural connectivity can predict sex, age, general cognitive function and general psychopathology, testing different ML algorithms from deep learning (DL) model (BrainNetCNN) to classical ML methods. We modelled N = 8183 structural connectomes from UK Biobank using six different structural network weightings obtained from diffusion MRI. Streamline count generally provided the highest prediction accuracies in all prediction tasks. DL did not improve on prediction accuracies from simpler linear models. Further, high correlations between gradient attribution coefficients from DL and model coefficients from linear models suggested the models ranked the importance of features in similar ways, which indirectly suggested the similarity in models'' strategies for making predictive decision to some extent. This highlights that model complexity is unlikely to improve detection of associations between structural connectomes and complex phenotypes with the current sample size.     

Some epidemiological aspects of stroke: mortality/morbidity trends, age, sex, race, socioeconomic status.

BACKGROUND AND PURPOSE: The reasons for decreasing stroke mortality could be related to either decreasing incidence and/or improved prognosis. Thus far, secular trends of stroke have been analyzed either through mortality or morbidity data. This report examines both aspects simultaneously, on a nationwide basis, for the period 1968-1988. METHODS: Mortality statistics were based on the Compressed Mortality File. Estimates of morbidity were based on the National Hospital Discharge Survey. The Area Resource File was used to obtain county-specific socioeconomic statistics. RESULTS: The decline in stroke mortality continued through the 1970s and 1980s, whereas morbidity remained constant and possibly even increased. Mortality and morbidity rates were similar in both sexes, higher in blacks, and lower in other (primarily Asian) Americans. There was an inverse correlation between death rates and socioeconomic status, which was particularly marked in blacks. Temporal decline occurred in all strata. CONCLUSIONS: The observed decrease in stroke mortality rates results most probably from an improved survival rather than from a decline in incidence. The abundance of new drugs and screening programs may not have affected the overall morbidity of stroke, possibly because of inefficient treatment regimens.     

Parkinsonism death rates by race, sex, and geography

Age-adjusted death rates for Parkinson's disease (PD) in the United States from 1959 to 1961 demonstrated significantly lower rates for blacks than for whites, with rates for Oriental Americans the same as for whites. All racial groups showed a male preponderance. Both whites and blacks had a similar excess of PD death rates for residents of the four northern census regions of the US over their rates for the three southern regions. Within each region the sex and race differences remained. Thus, blacks in the US appear to be "protected" against PD, but they share the north: south gradient seen for whites. Race, sex, and geography would therefore seem to be independent risk factors for PD, providing further evidence that this may then be an acquired, environmental disease.     

Electro-cortical implicit race bias does not vary with participants' race or sex

Earlier research found evidence for electro-cortical race bias towards black target faces in white American participants irrespective of the task relevance of race. The present study investigated whether an implicit race bias generalizes across cultural contexts and racial in- and out-groups. An Australian sample of 56 Chinese and Caucasian males and females completed four oddball tasks that required sex judgements for pictures of male and female Chinese and Caucasian posers. The nature of the background (across task) and of the deviant stimuli (within task) was fully counterbalanced. Event-related potentials (ERPs) to deviant stimuli recorded from three midline sites were quantified in terms of mean amplitude for four components: N1, P2, N2 and a late positive complex (LPC; 350–700 ms). Deviants that differed from the backgrounds in sex or race elicited enhanced LPC activity. These differences were not modulated by participant race or sex. The current results replicate earlier reports of effects of poser race relative to background race on the LPC component of the ERP waveform. In addition, they indicate that an implicit race bias occurs regardless of participant’s or poser’s race and is not confined to a particular cultural context.     

Delusional theme, sex and age

In a retrospective study of 865 delusional syndromes, connections were investigated between delusional themes and the sex of patients, and the ages in which these themes extensively occurred. According to previous reports, the results of this investigation indicated that differences exist between the ages of manifestation regarding the themes of hypochondria, persecution, love and jealously. Furthermore, differences could be observed between males and females in relation to the frequency of choice of particular themes, as well as the age of occurrence. Based on psychological studies concerned with the content's dependence on motives we conclude that the age distribution of delusional themes corresponds to the main existential concerns in different life periods.     

Differences in directed functional brain connectivity related to age,sex and mental health

Functional interconnections between brain regions define the “connectome” which is of central interest for understanding human brain function. Resting‐state functional magnetic resonance (rsfMRI) work has revealed changes in static connectivity related to age, sex, cognitive abilities and psychiatric symptoms, yet little is known how these factors may alter the information flow. The commonly used approach infers functional brain connectivity using stationary coefficients yielding static estimates of the undirected connection strength between brain regions. Dynamic graphical models (DGMs) are a multivariate model with dynamic coefficients reflecting directed temporal associations between nodes, and can yield novel insight into directed functional connectivity. Here, we leveraged this approach to test for associations between edge‐wise estimates of direction flow across the functional connectome and age, sex, intellectual abilities and mental health. We applied DGM to investigate patterns of information flow in data from 984 individuals from the Human Connectome Project (HCP) and 10,249 individuals from the UK Biobank. Our analysis yielded patterns of directed connectivity in independent HCP and UK Biobank data similar to those previously reported, including that the cerebellum consistently receives information from other networks. We show robust associations between information flow and age and sex for several connections, with strongest effects of age observed in the sensorimotor network. Visual, auditory and sensorimotor nodes were also linked to mental health. Our findings support the use of DGM as a measure of directed connectivity in rsfMRI data and provide new insight into the shaping of the connectome during aging.     

Correlation between cranial vault size and brain size over time: preliminary MRI evaluation

OBJECTIVES: To correlate changes of cranial vault measurements of an adult population during the aging process with brain size using the maximum width of the third ventricle in the axial AC-PC plane. MATERIALS AND METHODS: Prospective study of 126 adult subjects (range: 20 to 80 years) with normal brain MRI and without history of neuropsychiatric disorder. MEASUREMENTS INCLUDED: Cranial vault (Maximum length: Glabella-Opisthocranion, Maximum width: euryon-euryon, and maximum height: Basion-Vertex) measurements and maximum width of the third ventricle in the A C-PC plane. RESULTS: Vault measurements (length, width, high) were similar for every age group, irrespective of gender. The variability of cranial vault measurements between individuals was low (<1 cm). Cranial vault measurements were larger for men, but this was not significant when adjusted for body height Comparatively, a gradual widening of the third ventricle, with an exponential behavior, was observed with advancing age. CONCLUSION: Our results indicate that cranial vault measurements are stable over time (between 20-80 years) comparatively to brain atrophy with advancing age. The low variability of cranial vault measurements and their stability over time should be taken into account during segmentation and normalization of brain parenchymal structures.