Biology subjects

Sexton, C. E.

Publications and source records attributed to Sexton, C. E..

3 recordsLinked to original sources

bioRxiv2020

Sleep Efficiency Relates to Hippocampal Integrity Decline in β-Amyloid Positive Adults

BackgroundTo test the hypothesis that worse self-reported sleep relates to memory decay and reduced hippocampal integrity as indexed by increased intra-hippocampal water diffusion, and that the relations are stronger in the presence of {beta}-amyloid (A{beta}) accumulation, a marker of Alzheimers disease (AD) pathology. MethodsTwo-hundred and forty-three cognitively healthy participants, aged 19-81 years, completed the Pittsburgh Sleep Quality Index, and 2 diffusion tensor imaging sessions, on average 3 years apart, allowing measures of decline in hippocampal microstructural integrity as indexed by increased mean diffusivity. We measured memory decay using delayed recall from the California Verbal Learning Test. 18F-Flutemetamol positron emission tomography, in 108 participants above 44 years of age, yielded 23 A{beta} positive. Genotyping enabled controlling for APOE {varepsilon}4 status, and polygenic scores for sleep efficiency and AD. ResultsWorse global sleep quality and sleep efficiency related to more rapid reduction in hippocampal microstructural integrity over time. Focusing on sleep efficiency, the relation was stronger in presence of A{beta} accumulation. Sleep efficiency related to memory decay indirectly via hippocampal integrity decline. The results were not explained by genetic risk for sleep efficiency and AD. ConclusionsPoor self-reported sleep efficiency related to decline in hippocampal integrity, especially in the presence of A{beta} accumulation. Poor sleep and hippocampal microstructural decline may partly explain memory decline in older adults with A{beta} pathology. The relationships were not explained by genetic risk. Poor self-reported sleep efficiency might constitute a risk factor for AD, although the causal mechanisms driving the of observed associations remain unknown.

neuroscience↗

bioRxiv2020

Mid-life and late life activities and their relationship with MRI measures of brain structure and functional connectivity in the UK Biobank cohort

INTRODUCTIONThis study aimed to evaluate whether mid-life and late life participation in leisure activities is linked to measures of brain structure, functional connectivity and cognition in early old age. METHODSWe examined data collected from 7,152 participants of the UK Biobank study. Weekly participation in six leisure activities was assessed twice. A cognitive battery and 3T MRI brain scan were administered at the second visit. RESULTSWeekly computer use at mid-life associated with larger volumes of the left putamen and higher scores for fluid intelligence, alphanumeric and numeric trail making tasks and prospective memory. Frequent attendance at a sports club or gym at mid-life was associated with stronger connectivity of the sensorimotor network with the lateral visual and cerebellar networks. No other associations were significant. DISCUSSIONThis study demonstrates that not all leisure activities contribute to cognitive health equally, nor is there one unifying neural signature across leisure activities.

neuroscience↗

bioRxiv2019

Paired-end Mappability of Transposable Elements in the Human Genome

Though transposable elements make up around half of the human genome, the repetitive nature of their sequences makes it difficult to accurately align conventional sequencing reads. However, in light of new advances in sequencing technology, such as increased read length and paired-end libraries, these repetitive regions are now becoming easier to align to. This study investigates the mappability of transposable elements with 50bp, 76bp and 100bp paired-end read libraries. With respect to those read lengths and allowing for 3 mismatches during alignment, over 68%, 85%, and 88% of all transposable elements in the RepeatMasker database are uniquely mappable, suggesting that accurate locus-specific mapping of older transposable elements is well within reach.

genomics↗