A fascinating new study from scientists at UC Berkeley has homed in on exactly which phase of sleep seems to best keep anxiety levels in check. The research both affirms a causal association between sleep and anxiety, and suggests sleep deprivation lowers activity in the prefrontal cortex, an area of the brain that helps regulate our emotions.

For well over a century scientists have observed a correlation between sleep disruption and mood disorders such as anxiety and depression. Only in the last few years have clear neural mechanisms been discovered helping us understand exactly what our brains are doing when we are asleep, and how physiologically disruptive sleep deprivation can be.

A new study from UC Berkeley has focused more specifically on how sleep can modulate a person’s anxiety levels. Using a number of experimental measures, including polysomnography and functional MRI, the research first found that just one night of sleep deprivation resulted in 50 percent of the study subjects reporting anxiety levels the next day equal to those detected in subjects with clinically diagnosed anxiety disorders.

In a surprise to many researchers around the world, Chinese authorities recently approved a novel drug claimed to improve cognitive function in patients with Alzheimer’s disease. The drug, derived from a marine algae, is the first new Alzheimer’s drug to reach the market anywhere in the world in almost 20 years, and is suggested to reduce neuroinflammation by modulating a person’s gut microbiome.

GV-971, or sodium oligomannate, is derived from a common form of seaweed called brown algae. For several years the compound has been under investigation in China as a treatment to slow, or even reverse, cognitive decline associated with mild to moderate cases of Alzheimer’s disease.

The latest announcement from China’s National Medical Products Administration (NMPA) has granted the drug “conditional approval”, meaning it is to be fast-tracked to market based on positive early Phase 3 trial results. The “conditional approval” requires ongoing studies to verify efficacy and safety, however, it can now move to open market sales in China within the next month or two.

Focused ultrasound (FUS) can be used to help drugs pass from the bloodstream into the brain, but the technique’s effectiveness depends on the ultrasound pressure and the size of the drug molecules. Michael Valdez and colleagues at the University of Arizona measured how thoroughly differently sized molecules diffused into mouse brains under a range of ultrasound intensities, and found that the largest molecules could not be delivered under any safe FUS regime. The results set a limit on the types of drugs that might one day be used to treat neurological conditions like Alzheimer’s and Parkinson’s disease (Ultrasound Med. Biol. 10.1016/j.ultrasmedbio.2019.08.024).

Usually, the brain is isolated from substances circulating in the bloodstream by the blood–brain barrier (BBB), a semipermeable layer of cells that permits only certain molecules to pass. This restricts the range of drugs that can be used in the brain to small, hydrophobic molecules (such as alcohol and caffeine), other small drugs like psychotropics and some antibiotics. Extending that range would open the door to new therapeutic possibilities, says Theodore Trouard, who led the team. “The ability to temporarily and safely open the BBB to allow drugs into the brain would help address a number of neurological diseases for which there is currently no effective treatment.”

Previous research has shown that such opening can be achieved by focusing an ultrasound beam in the brain while gas microbubbles circulate in the blood. The microbubbles – perfluorocarbon-filled lipid shells about 1 µm across – are inert while they move around the body, but rapidly expand and contract in the local pressure fluctuations caused by the ultrasound field. Mechanical forces exerted by this phenomenon create temporary gaps in the layer of cells that make up the BBB, giving larger molecules a chance to breach the brain’s defences.