About one-third of individuals suffering from depression are at risk for treatment resistance. Whereas inhaled 50% nitrous oxide has early antidepressant effects on individuals with treatment-resistant major depression (TRMD), adverse effects can occur at this concentration. In this phase 2 clinical trial, Nagele et al. studied the effects of a single 1-hour treatment with 25% nitrous oxide on depression symptoms in those with TRMD, finding that this lower concentration had comparable efficacy to 50% nitrous oxide over several weeks but was associated with significantly fewer adverse effects. These results highlight that lower concentrations of nitrous oxide may be a useful treatment for TRMD.

Twenty-five percent inhaled nitrous oxide improves symptoms of treatment-resistant major depression with fewer adverse effects than the 50% concentration.

“De novo” genes may have paved the way for humans’ big brains.

In 2012, Nedergaard also helped to discover a network of thin tubes that collect waste fluid from brain cells, known as the glymphatic system. These tubes may drain into the outgoing cerebrospinal fluid, says Nedergaard.

The waste products of brain cells include proteins called beta-amyloid and tau that are thought to be involved in Alzheimer’s disease when they build up in excessive amounts.

In both mice and people, the SLYM also contains immune cells, so it may allow them to detect signs of infection present in the cerebrospinal fluid, says Nedergaard. “It is loaded with immune cells.”