Corpse-spotting: Why seeing the dead could be bad for your health

Researchers find death perception triggers neuronal activation in flies, leading to reduced lifespans.

“I see dead people.” Good news for movies, bad news for flies, it would seem.

Researchers at the University of Michigan have found the link between death perception (no, not the Death Metal band) and reduced aging in flies. A new study, published in the open access journal PLOS Biology shows that specific neurons in the fly – R2 and R4 neurons to be specific – are activated when flies encounter other dead flies, and that this increased neuronal activity leads to more rapid aging [1].

Longevity.Technology: While it is known that the aging process can be affected by the environment, the idea that perceptual experiences can affect aging seems rather far-fetched – but it does happen. How it happens, however, has been somewhat of a mystery, although one example of this phenomenon is the effect of ‘death perception’ in fruit flies. Previously, the Michigan group had shown that when fruit flies see dead fruit flies, they experience advanced aging [2], and that this depends on a type of serotonin receptor. In a new follow-up study, the researchers expand on the details of this process.

The researchers conducted a series of experiments in fruit flies that demonstrated that a specific group of neurons is responsible. Fluorescent tagging showed that exposure to dead flies led to increased activity in a region of the fly brain called the ellipsoid body.

Corpse-spotting: Why seeing the dead could be bad for your health
A handful of neurons in the fly brain were identified as a key component of how adverse experiences, in this case the perception of dead conspecifics, modulate aging. Photograph: Christi Gendron

By silencing different ring neurons in this region, the researchers showed that two types of ring neurons, R2 and R4, are necessary for the effect; additional tests demonstrated that the key is a serotonin receptor 5-HT2A, which is located on these neurons. Finally, the researchers showed that when these neurons were artificially activated, fruit fly lifespans decreased, even when flies did not actually experience any death perception [1].

Coauthor Scott Pletcher explained: “We identified specific neurons and evolutionarily conserved molecules in the fly brain that help tune rates of aging in response to environmental conditions and experiences [3].”

You might be wondering what practical use this research might be to the field of longevity – extending human lifespan and healthspan – “Don’t look at dead people” might seem to be rather obvious advice. However, understanding the mechanism of death perception and unraveling exactly how neural circuits like this regulate aging could lead to the development of targeted drug therapies that slow the aging process in humans.


Main image: wirestock/Freepik.
Fly photograph: Christi Gendron (CC-BY 4.0)