Cortisol, cognition and the ageing prefrontal cortex

The structural and functional decline of the ageing human brain varies by brain region, cognitive function and individual. The underlying biological mechanisms are poorly understood. One potentially important mechanism is exposure to glucocorticoids (GCs; cortisol in humans); GC production is increasingly varied with age in humans, and chronic exposure to high levels is hypothesised to result in cognitive decline via cerebral remodelling. However, studies of GC exposure in humans are scarce and methodological differences confound cross-study comparison. Furthermore, there has been little focus on the effects of GCs on the frontal lobes and key white matter tracts in the ageing brain. This thesis therefore examines relationships among cortisol levels, structural brain measures and cognitive performance in 90 healthy, elderly community-dwelling males from the Lothian Birth Cohort 1936. Salivary cortisol samples characterised diurnal (morning and evening) and reactive profiles (before and after a cognitive test battery). Structural variables comprised Diffusion Tensor Imaging measures of major brain tracts and a novel manual parcellation method for the frontal lobes. The latter was based on a systematic review of current manual methods in the context of putative function and cytoarchitecture. Manual frontal lobe brain parcellation conferred greater spatial and volumetric accuracy when compared to both single- and multi-atlas parcellation at the lobar level. Cognitive ability was assessed via tests of general cognitive ability, and neuropsychological tests thought to show differential sensitivity to the integrity of frontal lobe sub-regions. The majority of, but not all frontal lobe test scores shared considerable overlap with general cognitive ability, and cognitive scores correlated most consistently with the volumes of the anterior cingulate. This is discussed in light of the diverse connective profile of the cingulate and a need to integrate information over more diffuse cognitive networks according to proposed de-differentiation or compensation in ageing. Individuals with higher morning, evening or pre-test cortisol levels showed consistently negative relationships with specific regional volumes and tract integrity. Participants whose cortisol levels increased between the start and end of cognitive testing showed selectively larger regional volumes and lower tract diffusivity (correlation magnitudes <.44). The significant relationships between cortisol levels and cognition indicated that flatter diurnal slopes or higher pre-test levels related to poorer test performance. In contrast, higher levels in the morning generally correlated with better scores (correlation magnitudes <.25). Interpretation of all findings was moderated by sensitivity to type I error, given the large number of comparisons conducted. Though there were limited candidates for mediation analysis, cortisol-function relationships were partially mediated by tract integrity (but not sub-regional frontal volumes) for memory and post-error slowing. This thesis offers a novel perspective on the complex interplay among glucocorticoids, cognition and the structure of the ageing brain. The findings suggest some role for cortisol exposure in determining age-related decline in complex cognition, mediated via brain structure

A molecular genetic approach to vision research: Crystallin gene expression in the lens

Recent work from our laboratory on the molecular genetics of the lens crystallins is reviewed briefly. Examples of how cDNA and genomic clones have been used for investigating the structure and expression of lens genes are described. Present evidence indicates that two inherited cataracts in mice may be associated with specific defects in crystallin gene expression. We anticipate that molecular genetic investigations in vision and ophthalmology will advance our basic understanding of the eye, reveal the basis of hereditary defects in the visual system, and contribute to our knowledge of the eukarvotic genome

Clinical profiles associated with influenza disease in the ferret model.

Influenza A viruses continue to pose a threat to human health; thus, various vaccines and prophylaxis continue to be developed. Testing of these products requires various animal models including mice, guinea pigs, and ferrets. However, because ferrets are naturally susceptible to infection with human influenza viruses and because the disease state resembles that of human influenza, these animals have been widely used as a model to study influenza virus pathogenesis. In this report, a statistical analysis was performed to evaluate data involving 269 ferrets infected with seasonal influenza, swine influenza, and highly pathogenic avian influenza (HPAI) from 16 different studies over a five year period. The aim of the analyses was to better qualify the ferret model by identifying relationships among important animal model parameters (endpoints) and variables of interest, which include survival, time-to-death, changes in body temperature and weight, and nasal wash samples containing virus, in addition to significant changes from baseline in selected hematology and clinical chemistry parameters. The results demonstrate that a disease clinical profile, consisting of various changes in the biological parameters tested, is associated with various influenza A infections in ferrets. Additionally, the analysis yielded correlates of protection associated with HPAI disease in ferrets. In all, the results from this study further validate the use of the ferret as a model to study influenza A pathology and to evaluate product efficacy

Asthma and Anxiety in Children and Adolescents: Characteristics and Treatment Outcomes.

ObjectiveThis study (a) examined anxious youth with and without asthma on measures of negative self-talk, parental psychopathology, worry content, physical symptoms, panic symptoms, generalized symptoms, and separation anxiety symptoms, and (b) tested if outpatient CBT or medication were differentially effective in reducing anxiety for youth with asthma and anxiety. Methods: This secondary analysis separated youth with an anxiety disorder into asthma and non-asthma groups. Youth were also compared on response to treatments (i.e., CBT, sertraline, combined, and placebo). Results: A total of 488 participants participated in the original study, with an average age of 10 years (SD 2.87). Youth with comorbid asthma and anxiety demonstrated higher rates of negative self-talk. Youth with comorbid asthma and anxiety did not differ from the non-asthma group on measures of physical symptoms, anxiety disorder specific symptoms, parental psychopathology or worry content. Youth with asthma and anxiety responded similarly to the non-asthma group to treatment across treatment conditions. Conclusions: Treatment was comparably effective for youth with comorbid asthma and anxiety and youth with anxiety. Future research could examine the effects of psychopharmaceuticals on asthma and anxiety comorbidity

Asthma and anxiety in children and adolescents: characteristics and treatment outcomes.

OBJECTIVE: This study (a) examined anxious youth with and without asthma on measures of negative self-talk, parental psychopathology, worry content, physical symptoms, panic symptoms, generalized symptoms, and separation anxiety symptoms, and (b) tested if outpatient CBT or medication were differentially effective in reducing anxiety for youth with asthma and anxiety. METHODS: This secondary analysis separated youth with an anxiety disorder into asthma and non-asthma groups. Youth were also compared on response to treatments (i.e. CBT, sertraline, combined, and placebo). RESULTS: A total of 488 participants participated in the original study, with an average age of 10 years (SD 2.87). Youth with comorbid asthma and anxiety demonstrated higher rates of negative self-talk. Youth with comorbid asthma and anxiety did not differ from the non-asthma group on measures of physical symptoms, anxiety disorder specific symptoms, parental psychopathology, or worry content. Youth with asthma and anxiety responded similarly to the non-asthma group to treatment across treatment conditions. CONCLUSIONS: Treatment was comparably effective for youth with comorbid asthma and anxiety and youth with anxiety. Future research could examine the effects of psychopharmaceuticals on asthma and anxiety comorbidity

Elevated stearoyl-CoA desaturase-1 expression in skeletal muscle contributes to abnormal fatty acid partitioning in obese humans

SummaryObesity and type 2 diabetes are strongly associated with abnormal lipid metabolism and accumulation of intramyocellular triacylglycerol, but the underlying cause of these perturbations are yet unknown. Herein, we show that the lipogenic gene, stearoyl-CoA desaturase 1 (SCD1), is robustly up-regulated in skeletal muscle from extremely obese humans. High expression and activity of SCD1, an enzyme that catalyzes the synthesis of monounsaturated fatty acids, corresponded with low rates of fatty acid oxidation, increased triacylglycerol synthesis and increased monounsaturation of muscle lipids. Elevated SCD1 expression and abnormal lipid partitioning were retained in primary skeletal myocytes derived from obese compared to lean donors, implying that these traits might be driven by epigenetic and/or heritable mechanisms. Overexpression of human SCD1 in myotubes from lean subjects was sufficient to mimic the obese phenotype. These results suggest that elevated expression of SCD1 in skeletal muscle contributes to abnormal lipid metabolism and progression of obesity

Correlates of Survival in HPAI-Infected Ferrets.

<p>Correlates of Survival in HPAI-Infected Ferrets.</p