The relationship between gonadal hormones and neurocognitive functioning in healthy men and women and patients with schizophrenia

The primary aim of this thesis was to examine differences between healthy men and women and men and women with schizophrenia in relation to neurocognitive functioning. The thesis also examined the role of organisational influences of gonadal hormones and gonadotropins to cognitive performance. This was investigated in three studies. Study 1 examined the differences between healthy men and women on a sexually dimorphic cognitive battery (comprising mental rotation, modified judgement of line orientation, computerized Benton judgement of line orientation, cognitive inhibition, letter and category fluency tasks, and a working memory task) in a group of healthy men (n= 42) and women (n = 42). The study also looked at the relationship of organisational influences of gonadal hormones (estrogen, testosterone, progesterone), gonadotropins (lutenizing hormone; LH, follicle stimulating hormones; FSH) and sex hormone binding globulin; SHBG to these cognitive tasks. Study 2 investigated the role of gonadal hormones and the stress hormone cortisol to neurocognitive functioning (comprising domains of attention, verbal abilities, language, memory, executive functioning, motor and speed of information processing) and symptomatology (using the Positive and Negative Syndrome Scale; PANSS) in patients (N = 37) with schizophrenia. Study 3 examined the neural correlates of sex differences in performance on a block design mental rotation task and an overt verbal fluency paradigm using compressed sequence design in a group of healthy men (n = 9) and women (n = 10), controlling for the role of estrogen. Study I showed significant sex differences favouring men on all the spatial tasks and on a cognitive inhibition task, and differences favouring women on the category fluency task. Significant relationships were found between specific conditions of the spatial and inhibition tasks and progesterone, LH, FSH and SHBG. Study 2 found no sex differences in neurocognitive performance in patients with schizophrenia but found that high levels of estrogen were related to low positive symptom scores. Within gender, cortisol levels related to poor performance on the information-processing domain. Study 3 showed sex differences favouring men on the mental rotation and favouring women on the verbal (phonological) fluency task. Analysing the sexes separately revealed activation in the right superior parietal lobe in men and women during mental rotation performance. In general, women activated a greater number of voxels compared to men on the mental rotation and verbal fluency tasks. No sex differences (comparing the groups) in neural activation were found on any of the cognitive tasks. These findings confirmed the previously cited sex differences in cognitive performance and show that with similar activation patterns, men and women showed differential behavioural performance, thus suggesting that women may need more resources to perform better. Overall, this thesis adds to a critical body of literature showing that the relationship between gonadal hormones and cognition is more unsettled than previously thought. The findings also show that hormones other than estrogen and testosterone may also moderate hormone cognition relationships in men and women

Effect of twist level and twist direction of core (double) yarn on dref-3 spun yarn

In this study, an attempt has been made to understand the behaviour of friction spun yarn by introducing doubled yarns as core with diversity in twist level and direction. ‘Z’ twisted 15tex (40s Ne) parent yarn has been used for doubling purposes. To examine the effect of doubling, three twist levels are chosen, viz. 50, 60 and 70 % of the parent yarn twist for both the directions viz. S and Z. Thus, six samples of doubled yarns are prepared. These samples are tested for the count, twist, breaking force and elongation. These yarns are introduced as core into DREF-3 friction spinning system; keeping the sheath fibre constant viz. combed cotton sliver of 0.15 hank for all the samples. The twist direction of the doubled yarn used as core is found to be the influential factor for the breaking force and elongation of the friction spun yar

The functional anatomy of semantic retrieval is influenced by gender, menstrual cycle, and sex hormones

This study examines the neurobiology of semantic retrieval and describes the influence of gender, menstrual cycle, and sex hormones on semantic networks. Healthy right-handed subjects (12 men, 12 women) were investigated with 3T-fMRI during synonym generation. Behavioral performance and sex hormone levels were assessed. Women were examined during the early follicular and midluteal cycle phase. The activation pattern in all groups involved left frontal and temporal as well as bilateral medial frontal, cingulate, occipital, basal ganglia, and cerebellar regions. Men showed greater left frontal activation than women in both menstrual cycle phases. Women yielded high correlations of left prefrontal activation with estradiol in the midluteal phase and with progesterone in both phases. Testosterone levels correlated highly with left prefrontal activation in all three groups. In all, we describe a cerebral network involved in semantic processing and demonstrate that it is significantly affected by gender and sex steroid hormones

Changes in neuronal activation patterns in response to androgen deprivation therapy: a pilot study

<p>Abstract</p> <p>Background</p> <p>A common treatment option for men with prostate cancer is androgen deprivation therapy (ADT). However, men undergoing ADT may experience physical side effects, changes in quality of life and sometimes psychiatric and cognitive side effects.</p> <p>Methods</p> <p>In this study, hormone naïve patients without evidence of metastases with a rising PSA were treated with nine months of ADT. Functional magnetic resonance imaging (fMRI) of the brain during three visuospatial tasks was performed at baseline prior to treatment and after nine months of ADT in five subjects. Seven healthy control patients, underwent neuroimaging at the same time intervals.</p> <p>Results</p> <p>ADT patients showed reduced, task-related BOLD-fMRI activation during treatment that was not observed in control subjects. Reduction in activation in right parietal-occipital regions from baseline was observed during recall of the spatial location of objects and mental rotation.</p> <p>Conclusions</p> <p>Findings, while preliminary, suggest that ADT reduces task-related neural activation in brain regions that are involved in mental rotation and accurate recall of spatial information.</p

Sex-specific cognitive abnormalities in early-onset psychosis

Objectives: Brain maturation differs depending on the area of the brain and sex. Girls show an earlier peak in maturation of the prefrontal cortex. Although differences between adult females and males with schizophrenia have been widely studied, there has been less research in girls and boys with psychosis. The purpose of this study was to examine differences in verbal and visual memory, verbal working memory, auditory attention, processing speed, and cognitive flexibility between boys and girls. Methods: We compared a group of 80 boys and girls with first-episode psychosis to a group of controls. Results: We found interactions between group and sex in verbal working memory (p = 0.04) and auditory attention (p = 0.01). The female controls showed better working memory (p = 0.01) and auditory attention (p = 0.001) than males. However, we did not find any sex differences in working memory (p = 0.91) or auditory attention (p = 0.93) in the psychosis group. Conclusions: These results are consistent with the presence of sex-modulated cognitive profiles at first presentation of early-onset psychosis

Sex Differences and Autism: Brain Function during Verbal Fluency and Mental Rotation

Autism spectrum conditions (ASC) affect more males than females. This suggests that the neurobiology of autism: 1) may overlap with mechanisms underlying typical sex-differentiation or 2) alternately reflect sex-specificity in how autism is expressed in males and females. Here we used functional magnetic resonance imaging (fMRI) to test these alternate hypotheses. Fifteen men and fourteen women with Asperger syndrome (AS), and sixteen typically developing men and sixteen typically developing women underwent fMRI during performance of mental rotation and verbal fluency tasks. All groups performed the tasks equally well. On the verbal fluency task, despite equivalent task-performance, both males and females with AS showed enhanced activation of left occipitoparietal and inferior prefrontal activity compared to controls. During mental rotation, there was a significant diagnosis-by-sex interaction across occipital, temporal, parietal, middle frontal regions, with greater activation in AS males and typical females compared to AS females and typical males. These findings suggest a complex relationship between autism and sex that is differentially expressed in verbal and visuospatial domains

Comparable cortical activation with inferior performance in women during a novel cognitive inhibition task

Men are hypothesised to perform better than women at tasks requiring cognitive inhibition. The present study applied whole-brain functional magnetic resonance imaging to investigate the neural correlates of cognitive inhibition using a novel task, requiring detection of numbers decreasing in numerical order, in relation to sex. The study involved 19 young healthy subjects (9 men, 10 women). Behavioural sex differences favouring men were found on the inhibition, but not on the automatization (i.e. detection of numbers increasing in numerical order), condition of the task. Significant areas of activation associated with cognitive inhibition included the right inferior prefrontal and bilateral dorsolateral prefrontal cortices, left inferior and superior parietal lobes, and bilateral temporal regions across men and women. No brain region was significantly differently activated in men and women. Our findings demonstrate that (a) cognitive inhibition is dependent on intact processes within frontal and parietal regions, and (b) women show inferior cognitive inhibition despite of comparable activation to men in relevant regions. Equated behavioural performance may elicit sex differences in brain activation. (C) 2004 Elsevier B.V. All rights reserved

Does self-perceived mood predict more variance in cognitive performance than clinician-rated symptoms in schizophrenia?

Symptoms are known to account for a small variance in some cognitive functions in schizophrenia, but the influence of self-perceived mood remains largely unknown. The authors examined the influence of subjective mood states, psychopathology, and depressive symptoms in cognitive performance in a single investigation in schizophrenia. A group of 40 stable medicated patients with schizophrenia (20 men, 20 women) and 30 healthy comparison subjects (15 men, 15 women) were assessed on neurocognitive measures of verbal abilities, attention, executive functioning, language, memory, motor functioning, and information processing. All subjects provided self-ratings of mood prior to cognitive testing. Patients were also rated on psychopathology and depressive symptoms. Patients performed worse than comparison subjects on most cognitive domains. Within the patient group, subjective feelings of depression-dejection, fatigue-inertia, confusion, and tension-anxiety predicted (controlling for symptoms) poor performance on measures of attention, executive function, and verbal memory. In the same group of patients, clinician-rated symptoms of psychopathology and depression predicted significantly poor performance only on tests of motor function. In comparison subjects, vigor related to better, and fatigue and inertia to worse, spatial motor performance. Self-perceived negative mood state may be a better predictor of cognitive deficits than clinician-rated symptoms in chronic schizophrenia patient