Biology subjects

Elmenhorst, D.

Publications and source records attributed to Elmenhorst, D..

3 recordsLinked to original sources

bioRxiv2024

Regional associations of sleep architecture and Alzheimer's disease pathology

ObjectiveRecent evidence suggests that disturbances of sleep architecture are linked to Alzheimers disease (AD) pathology. Here, we assessed the association between sleep architecture and regional amyloid and tau pathology employing a portable sleep-monitoring device in addition to PET imaging. Methods18 cognitively normal adults (CN; M(Age) = 64.06 (8.63), Sex (M/F) =6/12) and 18 patients with MCI/early AD (M(Age) = 67.33 (8.25), Sex (M/F) =9/9) were included from the "Tau Propagation Over Time" (T-POT) study. All subjects underwent amyloid ([11C]-PiB) and tau ([18F]-AV1451) PET imaging. PET images were normalized to MNI-space and intensity standardized to the whole cerebellum ([11C]-PiB) or the inferior cerebellum ([18F]-AV1451). Sleep monitoring was performed at home using the portable "Dreem" EEG-headband (Beacon Biosignal), which is a reliable and comfortable wireless alternative to the gold-standard polysomnography (PSG). Sleep recordings were performed within six months of the PET acquisitions. At least, one sufficient night had to be acquired, which was used to assess the sleep macrostructure for each individual. Total duration of sleep phases per minutes (i.e. REM, N1, N2, N3) and total sleep time were extracted. In a first step, a linear mixed model (LMM) was used to compare the groups in terms of duration of the different sleep stages across the nightly recordings. Given the results of this comparison, mean N1 and N3 duration were subsequently correlated with regional amyloid and tau pathology SUVRs of 34 cortical regions using Spearmans correlation. The reported results are based on one-tailed tests. All analyses were corrected for age. ResultsPatients with MCI/AD showed reduced N3 duration (p = .007) compared to the CN group. A trend was observed indicating that patients with MCI/AD exhibited longer N1 durations (p = .094); however, this difference did not reach statistical significance. Shorter N3 duration was associated with higher regional amyloid load in the paracentral lobe and the posterior cingulate gyrus, whereas longer N1 duration was linked to higher amyloid pathology in several regions, including the medial temporal lobe, cingulate cortex and the occipital lobe. Moreover, associations were observed between longer N1 duration and greater tau burden in regions comprising the temporal lobe, cingulate cortex, and medial-frontal areas of the brain. ConclusionDifferences in sleep architecture between healthy controls and MCI/AD may arise from regionally-specific accumulation patterns of AD pathologies. Although it remains unknown whether disruptions in sleep architecture are a cause or a consequence, a complex relationship between AD-aggregation pathology in specific brain regions and the different phases of sleep appears to emerge.

neuroscience↗

bioRxiv2023

Repeated Caffeine Intake Suppresses Cerebral Grey Matter Responses to Chronic Sleep Restriction in an A1 Adenosine Receptor-Dependent Manner.

Evidence has shown that both sleep loss and daily caffeine intake can induce changes in grey matter (GM). Caffeine is frequently used to combat sleepiness and impaired performance caused by insufficient sleep. It is unclear 1) whether daily use of caffeine could prevent or exacerbate the GM alterations induced by chronic sleep restriction, and 2) whether the potential impact on GM plasticity depends on individual differences in the availability of adenosine receptors, which are involved in mediating effects of caffeine on sleep and waking function. In this double-blind, randomized, controlled study, 36 healthy adults (aged 28.9 {+/-} 5.2 y/o; 15 females; habitual daily caffeine intake < 450 mg; 29 homozygous C/C allele carriers of the A2A adenosine receptor (A2AR) gene variant rs5751876 of ADORA2A) underwent a 9-day laboratory visit consisting of one adaption day, 2 baseline days (BL), 5-day sleep restriction (CSR, 5 h time-in-bed), and a recovery day (REC) after an 8-h sleep opportunity. Nineteen participants received 300 mg caffeine in coffee through the 5 days of CSR (CAFF group), while 17 matched participants received decaffeinated coffee (DECAF group). We measured the GM morphology on the 2nd BL Day, 5th CSR Day, and REC Day. Moreover, we used [18F]-CPFPX PET to quantify the baseline availability of A1 adenosine receptors (A1R) and their relation to GM plasticity. The voxel-wise multimodal whole-brain analysis on T1-weighted images controlled for variances of cerebral blood flow indicated a significant interaction between caffeine and CSR in four brain regions: 1) right temporal-occipital region, 2) right thalamus, 3) left dorsolateral, and 4) dorsomedial prefrontal region. The post-hoc analyses indicated increased GM intensity in the DECAF group in all four regions but decreased GM in the thalamus as well as dorsolateral and dorsomedial prefrontal regions in the CAFF group after sleep restriction. Furthermore, lower baseline subcortical A1R availability predicted larger reduction in the CAFF group after CSR of all brain regions except for the caffeine-associated thalamic reduction. In conclusion, our data suggest an adaptive upregulation in GM after 5-day CSR, while concomitant use of caffeine instead leads to a GM reduction. The lack of consistent association with individual A1R availability may suggest that CSR and caffeine affect GM plasticity predominantly by a different mechanism. Future studies on the role of adenosine A2A receptors (ADORA2A) in CSR-induced GM plasticity are warranted.

neuroscience↗

bioRxiv2023

A genetic variation in the adenosine A2A receptor gene contributes to variability in oscillatory alpha power in wake and sleep EEG and A1 adenosine receptor availability in the human brain

The EEG alpha rhythm (8-13 Hz) is one of the most salient human brain activity rhythms. Spectral power in the alpha range in wakefulness and sleep varies among individuals based on genetical predisposition, yet knowledge about the underlying genes is scarce. The EEG alpha oscillations are related to cerebral energy metabolism and modulated by the level of attention and vigilance. The neuromodulator adenosine is directly linked to energy metabolism as product of adenosine tri-phosphate (ATP) breakdown and acts as a sleep promoting molecule by activitating A1 and A2A adenosine receptors. We quantified EEG oscillatory alpha power in wakefulness and sleep, as well as A1 adenosine receptor availability by positron emission tomography with 18F-CPFPX, in a large sample of healthy volunteers carrying different alleles of gene variant rs5751876 of ADORA2A encoding A2A adenosine receptors. Oscillatory alpha power was higher in homozygous C-allele carriers (n = 27, 11 females) compared to heterozygous and homozygous carriers of the T-allele (n(C/T) = 23, n(T/T) = 5, 13 females) (F(18,37) = 2.35, p = 0.014, Wilks {Lambda} = 0.467). Across considered brain regions an effect of ADORA2A genotype on A1 adenosine receptor binding potential was found (F(18,40) = 2.62, p = 0.006, Wilks {Lambda} = 0.459) and after correction for multiple testing this effect was shown to be significant for circumscribed occipital region of calcarine fissures. A correlation between individual differences in oscillatory alpha power and adenosine receptor availability was found for the subgroup of female participants only. In conclusion: a genetic variation in the adenosinergic system affects individual alpha power, although a direct modulatory effect via the A1AR has been demonstrated for females only.

neuroscience↗