It has been said the amyloid hypothesis, like certain banks, may have become too big to fail [101]. The hypothesis may yet prove its merit, at least in some cases, through early intervention trials with amyloid-directed therapeutics [70],[71]. However, on the basis of the data discussed here, the role of Aβ as a primary cause of all AD remains debatable. We are therefore concerned by the suggestion that, if anti-Aβ treatments are successful in patients with EOAD, this would support an argument for treating all AD with anti-Aβ drugs [207]. Such a conclusion would merit questioning without direct clinical evidence that the treatments are effective in LOAD.

We are not arguing that Aβ has no role. In fact it may be a player in a more complex view of disease and, further, its role may even be variable. We suggest instead that to solve the complex riddle of AD, theoretical models must expand beyond Aβ as the central cause of dysfunction, instead including Aβ in a wider theory that accounts for the extensive data and advances in neuroscience that have accumulated over the last decade. Ultimately it is critical that any role for Aβ must be placed in the context of a holistic view of the disease that accounts for all the data.

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At Moab Khotsong, a gold and uranium mine located in the Witwatersrand Basin, within the Kaapvaal Craton, South Africa, University of Toronto researcher Oliver Warr and colleagues found large amounts of radiogenic helium, neon, argon and xenon, and an unprecedented discovery of krypton-86 — a never-before-seen tracer of this powerful reaction history.

The radiation also breaks apart water molecules in a process called radiolysis, producing large concentrations of hydrogen, an essential energy source for subsurface microbial communities deep in the Earth that are unable to access energy from the sun for photosynthesis.

Due to their extremely small masses, helium and neon are uniquely valuable for identifying and quantifying transport potential.

While the extremely low porosity of crystalline basement rocks in which these waters are found means the groundwaters themselves are largely isolated and rarely mix, accounting for their 1.2-billion-year age, diffusion can still take place.

"Solid materials such as plastic, stainless steel and even solid rock are eventually penetrated by diffusing helium, much like the deflation of a helium-filled balloon," Dr. Warr said.

"Our results show that diffusion has provided a way for 75-82% of the helium and neon originally produced by the radiogenic reactions to be transported through the overlying crust."

The authors stress that the insights on how much helium diffuses up from the deep Earth is a critical step forward, as global helium reserves run out, and the transition to more sustainable resources gains traction.

"Humans are not the only life forms relying on the energy resources of the Earth's deep subsurface," Dr. Warr said.

"Since the radiogenic reactions produce both helium and hydrogen, we can not only learn about helium reservoirs and transport, but also calculate hydrogen energy flux from the deep Earth that can sustain subsurface microbes on a global scale."

"These calculations are vital for understanding how subsurface life is sustained on Earth, and what energy might be available from radiogenic-driven power on other planets and moons in the Solar System and beyond, informing upcoming missions to Mars, Titan, Enceladus and Europa."