In 2013, a prostrated committee of clinical psychiatrists staggered across a finish line of their own creation after a long, fraught attempt to update the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition)—something of the bible for their field. The new edition was long awaited, repeatedly delayed, rife with controversy, and met with scorn. It was an ultimately failed attempt to modernize psychiatry, expand its definitions of disease, incorporate quantitative biomarkers like MRI brain scans, and marry the field to modern neuroscience, which went way too far for some and not nearly far enough for others. Ten years later, we are still trying. The latest attempt to marry psychiatry and neuroscience is reported this week from scientists at the Advanced Telecommunications Research Institute International in Kyoto, Japan, who mapped brain connections of 1,162 people using MRI and used machine learning to find patterns linked to depression (334 of the study subjects suffered from major depressive disorder). Their results suggest connections between the brain’s thalamus and its motor network could be “robustly” linked to depressive symptoms, scoring a point for the descriptive link between neurophysiology and mental illness. Abstract

Not to be outdone by the brain imaging crowd, researchers at McGill University in Montreal have shown that traces of tiny molecules in a teenager’s bloodstream can predict whether they suffer depression. They retrospectively analyzed 230 blood samples collected in two studies–called Teen Inflammation Glutamate Emotion Research (TIGER) and Growing Up in Singapore Towards Healthy Outcomes (GUSTO). (Who makes up these acronyms anyway?) Looking at these samples, the researchers discovered specific DNA-like fragments called microRNAs that appear enriched in children suffering clinical depression and downregulated in kids without depression. Those markers could be early indicators of vulnerability to depression, the researchers say, and recognizing that may help us uncover the ongoing developmental processes that shape lifelong risk. Abstract

Scientists at the University of Southern California in Los Angeles used machine learning to analyze the 3D MRI brain scans, genetic markers, and demographic data from some 2,500 people, and they used that analysis to predict when someone with mild cognitive impairment will progress to full-blown Alzheimer’s disease. They specifically report that their model accurately predicts whether someone will progress in the next two years, which should help efforts to enroll high-risk individuals into future clinical trials to test new drugs to slow or reverse the onset of dementia. Abstract

The progressive and alarmingly prevalent muscle strength-, mass-, and function-wasting phenomena known as sarcopenia is related to aging and is also a well-known predictor of depression. Physical exercise is known to prevent both sarcopenia and depression, which is a great example of nurture over nature—how changes in your environment, your lifestyle, or your habits can have significant, long-term effects on your brain. Now researchers at Hong Kong Polytechnic University have discovered the central role of the human molecule apelin in linking sarcopenia and depression. This signaling peptide is important for muscle contraction and blood pressure regulation, and the researchers showed it can influence hippocampal neuroplasticity and elicit antidepressant effects in rodents, mediating the crosstalk of the muscle and the brain in depression, they write, and providing a potential new therapeutic target for treating geriatric depression. Abstract

Scientists studying the sleep patterns of the common oceanic cephalopod cuttlefish have discovered a curious thing. This mini marine mollusk, a cousin to the octopus and squid, replays memories of its waking life as vibrant, changing skin patterns while asleep. While analyzing changes to these skin patterns, researchers at the Kavli Institute for Systems Neuroscience in Trondheim, Norway, and the Norwegian University of Science and Technology showed that the fish have altered activity in their chromatophores—organs found in their skin that are useful for camouflage. They contain pigment sacs that can be pulled open by small radial muscles to change their color and patterns. It turns out that the more cuttlefish experience social interactions while awake, the more they display those memories on their skin while asleep. It’s not clear what survival role this social-recall-driven-camouflage plays for the cuttlefish or how it’s specifically relevant to human psychology. Maybe for now it’s enough to think about how cool it would be if your superpower was the ability to camouflage yourself any time you passed out. Then you could easily extricate yourself from a boring meeting or an awkward social situation—simply by waking up and walking out, unnoticed as you go because you blend into your background. Abstract

Marine Biology Laboratory/Cephalopod Program

Finally, not to be confused with all the above presentations at the Society for Neuroscience meeting, we saw an interesting paper on the wires this week about the hidden joy in keeping happy secrets. Three-quarters of people surveyed say they are inclined to share joyous news as soon as they get it, but many times, we keep glad tidings to ourselves—things like marriage proposals, promotions, and pregnancies. Engagements may be kept quiet in order to share the news with parents first, job appointments may be embargoed until some formal announcement, and pregnancies are often kept secret throughout the first trimester out of fears of miscarriage. Now based on five experiments involving 2,500 people at Columbia University in New York, researchers found that keeping good news a secret may actually be beneficial: It makes you feel more energized and alive whether you ultimately share the news or not. “People sometimes go to great lengths to orchestrate revealing a positive secret to make it all the more exciting,” said Columbia’s Michael Slepian in a statement to the press. “This kind of surprise can be intensely enjoyable.” Journal of Personality and Social Psychology

Editor’s note: This week proto.life’s own Jason Socrates Bardi was attending Neuroscience 2023, the Society for Neuroscience’s annual meeting, which bills itself as “the world’s largest source of emerging news about brain science and health.” The first five items here were some of our favorite presentations.