Biology subjects

Miner, B.

Publications and source records attributed to Miner, B..

4 recordsLinked to original sources

bioRxiv2026

Greater hypoxic burden predicts weaker gray matter-CSF coordination independent of non-hypoxic arousals: Implications for glymphatic activity

Study ObjectivesObstructive sleep apnea (OSA) is a risk factor for neurodegeneration, and glymphatic impairment may be one mechanistic pathway. Anti-phase coordination between brain pulsations and CSF flow, reflecting compensatory CSF displacement during each vascular pulsation cycle, supports glymphatic activity. This study examined whether hypoxic burden and sleep fragmentation, two distinct OSA pathologies, are differentially associated with brain pulsation-CSF flow dynamics. MethodsThis cross-sectional study included 28 individuals with newly identified OSA and 8 without OSA. Participants completed in-lab polysomnography or WatchPAT testing, providing measures of hypoxic burden, quantified as time below 90% oxygen saturation (T90), and non-hypoxic sleep fragmentation, quantified as respiratory effort-related arousals (RERAs). Participants also completed 7T resting-state functional MRI to estimate global BOLD-CSF, defined as anti-phase cross-correlation between blood-oxygen-level-dependent (BOLD) signal and CSF inflow. Associations were examined using correlation and hierarchical regression. Exploratory analyses examined region-specific BOLD-CSF and brain pulsation strength, quantified as BOLD amplitude. ResultsGreater T90 was associated with weaker global BOLD-CSF, independent of RERAs and covariates ({beta}=0.08,p=0.03). Greater T90 was also associated with higher BOLD amplitude across temporal, frontal, and parietal regions, but this elevation in amplitude was not accompanied by stronger region-specific BOLD-CSF coupling ({beta}=0.001,p>0.05). In contrast, among regions where BOLD amplitude was not associated with T90, greater BOLD amplitude predicted stronger region-specific BOLD-CSF ({beta}=-0.004,p<0.001). RERAs were not associated with global BOLD-CSF or BOLD amplitude. ConclusionsIn OSA, hypoxic burden may be the primary feature associated with impaired brain pulsation and CSF dynamics that support glymphatic activity. These alterations may be pronounced in the temporal lobe, where elevated pulsations were uncoupled from compensatory CSF displacement.

neuroscience↗

bioRxiv2025

APOE4 homozygotes have less sleep fragmentation in late adulthood

Background and ObjectivesAPOE4, a genetic risk factor for Alzheimers Disease (AD), is associated with reduced functional connectivity of brain regions that regulate sleep, which may predispose persons to AD via altering sleep architecture. However, little is known about differences in sleep architecture by APOE genotype. MethodsThis cross-sectional study examined the association between APOE genotype and sleep architecture among middle-aged and older adults, using polysomnography (Sleep Heart Health Study, N=3,132). APOE genotype included: APOE4 heterozygotes, APOE4 homozygotes, APOE2 carriers, and APOE3 homozygotes. Macro sleep architecture was quantified using the percentage of time spent in rapid eye movement sleep (%REM), N1 (N1%), N2 (%N2), N3 (%N3), and arousal index. Micro sleep architecture was quantified as odds ratio product (ORP; a continuous measure of sleep depth) for overall sleep and each sleep stage, and spindle characteristics (power, density, and frequency). Linear regression was used, adjusting for covariates. ResultsThe mean age was 67, 53 percent were female, 24% were APOE4 heterozygotes, 2% were APOE4 homozygotes, 14% were APOE2 carriers, and 60% were APOE3 homozygotes. Macro sleep architecture did not vary across genotypes. Compared with APOE3 homozygotes, APOE4 homozygotes exhibited fewer arousals with age ({beta}=-0.33 per hour/year, p=0.04), resulting in significantly fewer arousals at age 70+. ORP decreased in a dose-response pattern with the number of APOE4 alleles during overall sleep and across all sleep stages (ORPAPOE3/3=0.94, ORPAPOE3/4=0.91, ORPAPOE4/4=0.87), and these group difference widened with each year of age. Finally, there was a trend for lower spindle density and power in APOE4 homozygotes relative to APOE3 homozygotes (ps=0.06). ConclusionsArousal threshold increased in a dose-response manner with each APOE4 allele, as evidenced by the findings on ORP. The differences in ORP between APOE3 homozygotes and APOE4 carriers widened further with age, paralleling age-related declines in arousal index among APOE4 homozygotes. Despite these indications of elevated arousal thresholds that might suggest less sleep fragmentation in APOE4 carriers, APOE4 homozygotes exhibited poorer sleep micro architecture, including trends toward reduced sleep spindle activity. Taken together, reduced arousability in APOE4 carriers may reflect abnormalities in cortical activation that blunt arousal rather than an indicator of healthier sleep.

physiology↗

bioRxiv2025

Basal forebrain volume is associated with cortical amyloid burden in cognitively unimpaired older adults at varying genetic risk for Alzheimers disease

BackgroundIn mild cognitive impairment and dementia due to Alzheimers disease (AD), postmortem and in vivo neuroimaging studies have demonstrated significant neuronal loss in the basal forebrain cholinergic system (BFCS), which provides the primary cholinergic input to the cerebral cortex. Within this region, atrophy is most prominent in the nucleus basalis of Meynert (nbM), a group of posteriorly clustered magnocellular neurons in the BFCS. However, less is known surrounding the relationship between amyloid deposition, BFCS atrophy, and medial temporal lobe (MTL) volume loss in the preclinical stages of AD. The current study investigates the relationship between sub-structural BFCS volume and cortical A{beta} burden in cognitively unimpaired middle-aged individuals at varying genetic risk for AD. MethodsCognitively unimpaired participants aged 50-65 with a first-degree family history for AD were genetically screened to select three groups: APOE genotype {varepsilon}4{varepsilon}4 (n=15), {varepsilon}3{varepsilon}4 (n=15), and {varepsilon}3{varepsilon}3 (n=15), matched for age and sex. Participants underwent imaging with [11C]PiB PET and structural 3T MRI. Distribution volumes ratios (DVR) with a whole cerebellum reference region were calculated for [11C]PiB PET analyses. BFCS sub-structural volumes were obtained from the SPM8 Anatomy Toolbox (Cholinergic nuclei [Ch] 1-3, Ch4). MTL subregional volumes (entorhinal cortex, hippocampus, amygdala, parahippocampal gyrus) were extracted using Freesurfer. ResultsBFCS amyloid burden was highest among APOE {varepsilon}4 homozygotes (Ch1-3, F(2, 42)=3.26, P=0.048; Ch4, F(2, 42)=3.82, P= 0.03). Ch4 (nbM), but not Ch1-3 volume, was found to be inversely associated with global A{beta} burden (Pearson r=-0.40, P=0.007). MTL subregional volumes were not associated with global A{beta} burden in the pooled sample. Exploratory analyses in groups stratified by amyloid positivity demonstrated reduced Ch4 volume (P=0.032) and significant inverse associations between Ch4 volume and amyloid burden (Pearson r = -0.70, P=0.02) in A{beta}+ participants. ConclusionsWe observed nbM (Ch4), but not MTL volume, to be significantly inversely associated with cortical amyloid burden in cognitively unimpaired, A{beta}+, middle-aged adults at varying genetic risk for AD. These findings provide further in vivo evidence suggesting that nbM atrophy is an early structural correlate of AD pathogenesis, potentially preceding MTL atrophy.

neuroscience↗

bioRxiv2025

Lower slow wave sleep and rapid eye-movement sleep are associated with brain atrophy of AD-vulnerable regions

Study objectivesSleep deficiency is associated with Alzheimers disease (AD) pathogenesis. We examined the association of sleep architecture with anatomical features observed in AD: (1) atrophy of hippocampus, entorhinal, inferior parietal, parahippocampal, precuneus, and cuneus regions ("AD-vulnerable regions") and (2) cerebral microbleeds. MethodsIn 271 participants of the Atherosclerosis Risk in the Communities Study, we examined the association of baseline sleep architecture with anatomical features identified on brain MRI 13[~]17 years later. Sleep architecture was quantified as the proportion of slow wave sleep (SWS), proportion of rapid eye-movement sleep (REM), and arousals index using polysomnography. Outcomes included (1) volumetric measurements of each AD-vulnerable region and (2) the presence of any cerebral microbleeds (CMBs) and that of lobar CMBs, which are more specifically associated with AD. We analyzed the association of each sleep predictor with each MRI outcome, adjusting for covariates. ResultsHaving less SWS was associated with smaller inferior parietal region ({beta}=-44.19 mm3 [95%CI=-76.63,-11.76]) and cuneus ({beta}=-11.99 mm3 [-20.93,-3.04]) after covariate adjustment. Having less REM was associated with smaller inferior parietal region ({beta}=-75.52 mm3 [-129.34, -21.70]) and precuneus ({beta}=-31.93 mm3 [-63.79,-0.07]). After FDR adjustments, lower SWS and REM, respectively, were associated with smaller inferior parietal region. Arousal index was not associated with the volumes of AD-vulnerable regions. None of the sleep architecture variables were associated with CMBs or lobar CMBs. ConclusionsSleep deficiency is associated with the atrophy of the inferior parietal region, which is observed in early AD. Sleep architecture may be a modifiable risk factor for AD. Brief summarya. Current Knowledge/Study Rationale: two sentences summarizing why the study was doneWhile impaired sleep architecture has been associated with Alzheimers disease [AD] diagnosis and cognitive decline. To better understand the impact of sleep on AD pathogenesis, this study examined the association of sleep architecture with anatomical features observed in AD, including the atrophy of AD-vulnerable regions and CMBs. b. Study Impact: two sentences summarizing how the study impacts the fieldOur study shows that lower slow wave sleep and rapid eye movement sleep may be precipitating factors of inferior parietal region atrophy, which is associated with AD risk. Importantly, the current studys findings can help characterize underlying mechanisms of how sleep deficiency, a prevalent disturbance among middle-aged and older adults, may facilitate AD pathogenesis and cognitive impairment.

neuroscience↗