The sustained habit of sucking the hard nut wears into the enamel, eventually exposing the pulp.

The exposed pulp creates intense pain.

Arecoline, the psychoactive compound in the nut, also has analgesic properties — it numbs pain.

So continuing to suck the betel nut numbs the very pain that the nut itself has caused.

The researchers describe this as “a cycle of continued habitual use” — a feedback loop that mirrors the pharmacological dynamics of modern addiction, in which the substance both causes the problem and temporarily relieves it.

This cycle has an eerily familiar quality.