Alzheimer’s disease is a neurodegenerative disorder where pathological accumulation of amyloid-β and tau begin years before symptom onset. Emerging evidence suggests that β-blockers (β-adrenergic antagonists) increase brain clearance of these metabolites by enhancing cerebrospinal fluid flow. Our objective was to determine whether β-blockers treatments that easily cross the blood-brain barrier reduce the risk of Alzheimer’s disease compared to less permeable β-blockers. Data from the Danish national registers were used to identify a retrospective cohort of individuals with hypertension, and those treated with β-blockers were included in the analysis. Persons with indications for β-blocker use other than hypertension (e.g., heart failure) were only retained in a sensitivity analysis. β-blockers were divided into three permeability groups: low, moderate, and high. We used multivariable cause-specific Cox regression to model the effect of β-blocker blood-brain barrier permeability on time to dementia outcomes, adjusting for baseline comorbidities, demographics, and socioeconomic variables. Death was modeled as a competing risk. The 10-year standardized absolute risk was estimated as the averaged person-specific risks per treatment. In a cohort of 69,081 (median age = 64.4 years, 64.8% female) people treated with βBs for hypertension, highly BBB-permeable βBs were associated with reduced risk of Alzheimer’s disease versus low permeability βBs (−0.45%, p < 0.036). This effect was specific to Alzheimer’s diagnoses and did not extend to dementia in general. Propensity score analysis matching high and low BBB-permeable patients also detected a decreased Alzheimer’s risk (−0.92%, p < 0.001) in the high permeability group compared to the low, as did a 1-year landmark analysis (−0.57%, p < 0.029) in which events within the first year of follow-up were ignored as likely unrelated to treatment. Our results suggest that amongst people taking β-blockers for hypertension, treatment with highly blood-brain barrier permeable β-blockers reduces the risk of Alzheimer’s disease compared to low permeability drugs. Our findings support the hypothesis that highly permeable β-blockers protect against Alzheimer’s disease by promoting waste brain metabolite clearance.

Cerebrospinal fluid (CSF) flow through the brain parenchyma is facilitated by the astrocytic water channel aquaporin 4 (AQP4). Homeostatically regulated electroencephalographic (EEG) slow waves are a hallmark of deep non-rapid eye movement (NREM) sleep and have been implicated in the regulation of parenchymal CSF flow and brain clearance. The human AQP4 gene harbors several single nucleotide polymorphisms (SNPs) associated with AQP4 expression, brain-water homeostasis, and neurodegenerative diseases. To date, their role in sleep-wake regulation is unknown. To investigate whether functional variants in AQP4 modulate human sleep, nocturnal EEG recordings and cognitive performance were investigated in 123 healthy participants genotyped for a common eight-SNP AQP4haplotype. We show that this AQP4-haplotype is associated with distinct modulations of NREM slow wave energy, strongest in early sleep and mirrored by changes in sleepiness and reaction times during extended wakefulness. The study provides the first human evidence for a link between AQP4, deep NREM sleep, and cognitive consequences of prolonged wakefulness.

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Chronic cluster headache (CCH) is an excruciating disorder of unknown pathophysiology, but hypothalamic dysfunction has been implicated. CCH is difficult to treat but on a case-basis, the psychedelic compound psilocybin is said to have beneficial effects. In this first-ever clinical trial (NCT04280055), we evaluate in a small open-label study of CCH patients the feasibility and prophylactic effect of three low-to-moderate doses of psilocybin as well as effects on hypothalamic functional connectivity (FC), using functional magnetic resonance imaging. The treatment was well-tolerated and without serious adverse reactions. Attack frequency was on average reduced by 30% from baseline to follow-up (PFWER=0.008). One patient experienced 21 weeks of complete remission. Changes in hypothalamic-diencephalic FC correlated negatively with relative reduction in attack frequency, implicating this neural pathway in treatment response. Further clinical studies are warranted to confirm the safety and prophylactic efficacy of psilocybin for CCH and hypothalamic involvement in treatment response.