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

February 2, 2023

Social organization and longevity co-evolve

Comparing the genetics of 1,000 different mammals that live alone, in pairs, or in groups, researchers at the Chinese Academy of Sciences in Beijing have shown that mammals that live in groups generally live longer than solitary species, supporting the notion that social organization and longevity could have co-evolved. Looking at brain expression, they found 31 genes in 94 species involved in hormonal regulation and immunity that were associated with both social organization and longevity. “These results underscore a molecular basis for the influence of the social organization on longevity,” the authors write. Nature Communications

Implanted organoid tissue adopts function in rat brain

The irreversible loss of brain tissue due to a stroke, traumatic brain injury, or infection can have a huge and costly impact on a person’s life. But what if you could repair the damage? That’s the potential of stem cell therapy: grow replacement organoid tissue in a test tube and transplant it into the brain. It’s still far from reality, but an important step was realized this week when researchers at the University of Pennsylvania showed that human brain organoids adopted sophisticated function after they were transplanted into the visual cortexes of rats. They report that reciprocal synaptic pathways formed between the transplanted neurons from the organoid and the rat’s retina and other regions of its visual system. “Our findings offer a path forward for using engineered neural tissues to rebuild visual cortex and restore function in conditions such as cortical blindness” and other regions of the cortex, they write. Cell Stem Cell

Human cortical organoids survive well after they are transplanted into the injured visual cortex of adult rats. Jgamadze et al

Prescribing antidepressants for pain: time to rethink?

Chronic pain bedevils not only the countless millions of people who suffer from it but the inability of our health care enterprise to adequately deal with the problem. Drugs like ibuprofen provide some relief, but their long-term use is risky. Opioids are a bad solution because the risk of harm often outweighs the benefit. One treatment, used increasingly in the last 20 years, has been antidepressants. Now a systematic review of antidepressants for pain by doctors at the University of Sydney has found some evidence of their effectiveness, but not a lot. Looking at 156 clinical trials involving 25,000 people that made a total of 42 distinct antidepressant-versus-placebo comparisons, they found only 11 of the 42 showed any efficacy—and none of the evidence was of high quality. What this suggests, according to an accompanying editorial, is that “for most adults living with chronic pain, antidepressant treatment will be disappointing.” BMJ

Low vitamin D levels linked to suicide risk in U.S. veterans

We are reading a stunning result this week out of the Johns Hopkins Bloomberg School of Public Health in Baltimore and the Center of Excellence for Suicide Prevention at the Department of Veterans Affairs in Canandaigua, New York. Researchers there analyzed data from half a million U.S. military veterans who filled prescriptions for vitamin D supplements between 2010–2018, including 169,241 who took vitamin D2 and 490,885 who took vitamin D3. They accessed VA and Medicare records showing any instance of admission into an ER for a suicide attempt or intentional self-harm, and they compared those outcomes to more than half a million veterans who did not take vitamin D. They found that vitamin D3 and D2 supplementation were associated with 45 percent and 48 percent lower risk of suicide attempts and self-harm, especially in veterans with low blood serum levels of vitamin D and Black veterans. PLOS ONE

A road-map atlas of the human spinal cord

Researchers at Columbia University in New York and the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland, have developed an atlas of all the cell types in the human spinal cord that shows where the different glial and neuronal cells in the spine exist, which genes are expressed within them, and where in the cells those RNA transcripts are found. They call their publicly available resource the first comprehensive taxonomy of the adult human spinal cord, and according to the paper, it reveals how the unique molecular environments of specific cell types could contribute to chronic pain or neurodegeneration. Neuron

The buzz on the street, as seen on social

Using data from Twitter and Open Street Map, researchers at Kyoto Institute of Technology in Japan have demonstrated how social media can be used to explore people’s emotional states as they go about their daily lives in major cities. Analyzing some 2 million tweets from 200,000 people in London and San Francisco to determine whether those people were angry, happy, sad, or scared, they then geolocated the tweets to different locations. When people were on bridges, in train tunnels, or on their way to either, they tended to be filled with disgust. But when people were tweeting from hotels and restaurants, on the other hand, they had high levels of joy. While that may seem obvious, imagine how enlightened urban managers might prioritize their city’s pain points based on a fine-grained analysis of emotion in different city spots at different times through social media. PLOS ONE

To pee or not to pee

Smart toilets are a technology that makes sense, but problems arise immediately once you start to consider how to actually monitor people’s health in that most intimate setting. The potential is tremendous—passive monitoring of urine and stool could detect early signs of cancer, diabetes, and infections. They could help titer medication, speed certain clinical trials, monitor illegal or unhealthy drug use, and of course they could take your quantified self to a whole new level, but there are lots of considerations to take into account, not the least of which is privacy. Questions abound, such as whether bowel movements constitute personal health data (they do) and whether someone on a smart toilet outside a hospital would need to give informed consent (believe it or not, it’s not clear). Researchers at Stanford University tackle these questions in a perspective this week and call for establishing a better ethical framework around the technology. Science Translational Medicine