inflammation

The brain is like a city where every cell is a resident, and its fate depends on its neighbors. It used to be thought that the aging of each cell was its own private business: DNA damage accumulated, so the cell wore out on its own. But a new study shows that even a cell's ability to repair its DNA depends on who lives next door.

A mouse gets food that is missing a single amino acid, and within five days it loses a fifth of its weight. Its white fat turns darker, as if tiny stoves had lit up inside it. This is not hunger and not exercise: cysteine was simply removed from the diet. Cysteine is a building block of proteins that our body can make on its own from another amino acid, methionine.

In the newsreel of childhood, each of us has frames we'd like to rewind. But the film doesn't tear; it just gets scratched. Scientists from Scotland and the United States looked into those scratches at the molecular level and saw that a hard childhood leaves not only memories but also chemical marks on DNA that make cells age faster.

In a psychologist's quiet office, a fourteen-year-old fills out a questionnaire about childhood. The scores climb, and on the MRI scans the amygdala climbs with them: a small node deep in the brain that teaches us to fear and to remember danger. In a rat held in a narrow tube for three hours a day, the same structure grows faster than in its calm counterparts.

Old wiring in a house doesn't announce itself right away: the bulbs still glow, but the light has dimmed, and switches sometimes respond with a delay. Neuromuscular junctions age in much the same way. These are the contacts through which a nerve tells a muscle fiber to contract.

The skin of an older person is like an orchestra where the musicians are all in place, the instruments are tuned, but the conductor walks onstage later than he should. Infection with Staphylococcus aureus sets off an elaborate concert of immune cells in the skin, and it used to seem that with age the orchestra simply plays more quietly.

In a large orchestra, every musician knows their part: the violinist carries the melody, the cello holds the bass, the flute comes in during the pauses. If the violinist suddenly started playing the horn part, the music would fall apart, even though the instruments themselves would remain intact.

In September 2020, the sky over Oregon turned orange with wildfire smoke. Fifteen infant rhesus macaques, born just a few months earlier, breathed that smoke for nine days straight, simply because they lived in outdoor enclosures. Four years later, their blood told a story no one expected to hear.

Inflammation around an implant is like an orchestra rehearsal, where the conductor is the material itself and the musicians are immune cells. The score is the same, but it sounds different depending on who is sitting at the stands: young or old, male or female.

In 2023, in Belgium, 101 people aged 50 to 69 spent several days in a lab where their brains were scanned, their sleep was recorded, and they were asked to solve memory and attention tasks. That is how the COFITAGE dataset was born, describing each participant from five angles: molecular, structural, physiological, genetic and cognitive.

The orchestra plays a funeral march, and the conductor is not to blame for the choice of notes. But if he waves his baton more energetically, the music grows louder and the walls of the hall shake. Likewise, microglia, the brain's immune cells, don't start the disease, but they can turn a quiet fading into a collapse.

Imagine someone hauling two sacks up a hill. One is stuffed with sugar the body cannot process. The other is filled with the years the body has lived faster than the calendar. While the sacks are light, the climb is manageable. But if both are filled to the brim, the legs give way, and the person collapses not with one disease but with several at once.

The classroom goes quiet after the lesson, but the echo still rings in the child's head: faces, objects, places. It is this echo, not the lesson itself, that decides what will stay in memory. For the first time, researchers have caught it in children aged 6 to 17. Children memorized scenes inside an MRI scanner: they were shown a room, then an object or a face in a particular spot.

The liver is an orchestra in which every cell plays its part from a shared score. Males and females have different scores: in males, the genes responsible for detoxifying foreign substances and steroid hormones sound louder, while in females, the genes for fat metabolism and bile acids do.

Picture a muscle's control panel where buttons are removed with age. First to go are the buttons that handle hormone response, then those that kick off recovery after exercise. Researchers studied cell nuclei from vastus lateralis muscle biopsies from 287 donors aged 20 to 79 and saw exactly how these buttons disappear at the level of DNA packaging.