Amygdala

Sympathetic Tone

How hard the fight-or-flight side of the nervous system is running. Androgens raise tyrosine hydroxylase and change adrenergic receptor density, so a compound can lift this without touching mood directly. It is the shared cause behind a cluster people treat as four separate problems: a higher resting pulse, night sweats, a short fuse, and sleep that will not come.

Androgen Receptor

The receptor every anabolic-androgenic steroid is designed to hit. Binding moves it into the nucleus where it switches on genes for muscle protein synthesis, and in other tissues for hair loss, prostate growth and oil production.

NMDA Glutamate Receptor

The receptor that carries the calcium current behind learning. It is also the route by which too much glutamate kills the cell, so the same channel that writes memory is the one that destroys the neuron when it stays open too long.

Aggression

Hostility and short fuse. Reported consistently by users and in case series, and produced in blinded trials mainly at supraphysiological doses and mainly in a minority of people.

Anxiety

Restlessness, racing thoughts, a wired feeling. Multiple routes reach it: neurosteroid changes at GABA-A, glucocorticoid signalling, sleep loss and thicker blood.

Panic Attacks

Discrete episodes of overwhelming fear with a physical surge: pounding heart, breathlessness, a conviction that something is badly wrong. Different from sustained anxiety and worth its own entry because the plausible route is different too, running through sympathetic tone and a raised resting heart rate.

Paranoid Thinking

Suspicion of other people's motives that does not respond to evidence. Reported on the strongest compounds and named directly in the older user-facing notes on trenbolone. The evidence is case reports and self-report, and the self-report is unreliable in exactly the way the symptom predicts.

Amygdala Volume

The size of the threat detector on MRI. Long-term users had a larger right amygdala than non-using weightlifters, alongside weaker functional coupling between it and the regions that are supposed to regulate it.