Dopamine imbalance linked to hair-pulling in mice

A study using Sapap3 knockout mice links nucleus accumbens dysfunction and dopamine signaling to hair-pulling behaviors, offering clues for human trichotillomania.

Dopamine Imbalance in the Brain May Drive Trichotillomania

Researchers studied Sapap3 knockout mice to model trichotillomania. The mice showed compulsive grooming, more aggression, and stress sensitivity, especially in females. Under stress from bright light, grooming increased. Neural recordings showed lower activity in the nucleus accumbens, a key part of reward and habit control. Molecular work found higher dopamine levels and a shift in D1 and D2 receptor expression, along with elevated CREB and disrupted SAPAP3-SHANK3 interactions.

The team also explored oxytocin, a hormone linked to social behavior. A single dose reduced grooming bouts and aggression but raised total grooming time, showing a paradoxical effect. The study suggests that reward circuits and dopamine signaling could be central to hair pulling, while noting limits in translating mouse results to humans.

Taken together, the findings reinforce a neurobiological view of trichotillomania that centers on how reward circuits misfire. They point to a specific brain pathway, and to the idea that dopamine balance matters for repetitive behaviors.

But the leap to human treatment is not guaranteed. Small samples, sex bias in data, and reliance on a single animal model mean real life therapies are still uncertain. The work helps but does not decide the next step.

Highlights

Science moves forward one careful step at a time.