The week’s most astounding developments from the neobiological frontier.

October 27, 2022

Spermidine improves antitumor immunity in mice

Search online for a natural molecule found in the body known as spermidine (so named because it was first isolated from human semen) and your results page will be splashed with endless ads for life-extending supplements. And there is some basis for this. Preliminary studies have shown that spermidine levels decrease with aging and that giving organisms as diverse as yeast, worms, flies, and mice dietary supplements of spermidine can extend their lifespans and improve their cardiac, nervous system, liver, and immune function. Now researchers at Kyoto University in Japan have extended this body of knowledge by showing spermidine improves antitumor immunity in mice by activating CD8+ T cells and increasing mitochondrial function through upregulating fatty acid oxidation, which may be one of the ways it appears to contribute to longevity. We say “appears” deliberately because, as always, we have to ask when are we ever going to see the clinical proof with this supplement? Science

That’s the sound of your nightmare disappearing

A blissful night’s sleep is typically the dreamy end to a long day, but for millions of Americans, it’s the beginning of a daily dreadful nightmare—literally. Some 4 percent of the population suffer from debilitating nightmare disorders. They are plagued by recurring thoughts and images of anger, fear, threat, failure, and sadness during rapid eye movement (REM) sleep. The condition is typically treated with “imagery rehearsal therapy,” where people are trained to rethink their dreams during the day and reimagine the negative story lines of their nightmares into more positive ones, but 30 percent of people are not helped by this approach. Now researchers at the University of Geneva are suggesting a technique called targeted memory reactivation to improve therapy. It boosts the positive narratives by subjecting someone to a sensory cue like a smell or a sound while they consider them—and then relies on an EEG headband to detect when someone is in REM sleep and repeat that cue to them. It works. In a small study involving 36 people, they reported fewer nightmares and more positive dream emotions. Current Biology

New hope for hypoactive sexual desire disorder

The most common female sexual health complaint worldwide is a condition known as hypoactive sexual desire disorder (HSDD), which is the absence of sexual thoughts and/or desires causing personal distress. It affects some 10 percent of women and has limited treatment options. Hoping to expand these options, researchers at Imperial College London tested the effect of infusions of the hormone kisspeptin on 32 premenopausal women with HSDD. They showed them erotic stimuli and male faces while assessing their hormone levels and monitoring their brain activities via fMRI in a randomized clinical trial. The researchers found that kisspeptin deactivated brain regions associated with the disorder and activated other regions known to enhance male facial attractiveness and reduce sexual aversion. “These findings lay the foundations for the clinical applications of kisspeptin in women with hypoactive sexual desire disorder,” they write. JAMA Network Open

What science has to say about nap time

As any parent of a newborn knows, a baby’s sleep schedule can be chaotic at first, but within the first several months they normally even out into a biphasic or triphasic schedule where they sleep throughout the night and take one or two naps during the day—and eventually give up napping altogether. Now researchers at the University of Massachusetts, Amherst, are proposing a new hypothesis that accounts for the cognitive, physiological, and neural changes that accompany this transition from napping to no-napping as we age. They propose that changes to the brain’s hippocampus result in increased efficiency of memory storage, which reduces the drivers of sleep in the brain. Their framework could help guide napping policies at childcare and early education settings, they write. PNAS

Never again will birdsong be the same

Now is the time of year to go outside and trigger the pleasure centers in your brain with a little visual-sensory-orange-colored overload and ambient, rustling autumn sounds. Now is the time to unpack those fun Halloween decorations, scrape some seeds from a pumpkin, and scritch-scratch your yard with a rake. Now is the time to enjoy the migrating geese, the insane clouds of starlings, that lone blue heron, and those gorgeous calls of birdsong in the morning. Actually, any time may be the right time to listen to birds, according to researchers at King’s College London. Enrolling 1,292 people in a study using the Urban Mind app to examine the impact of hearing birds on mental well-being, they found that everyday encounters with birdlife are associated with long-lasting improvements in mental well-being—both in healthy people and also in people who are clinically depressed. Scientific Reports