Anxiety

Amygdala

The threat detector. Dense in androgen receptors, and the structure most implicated in the anger, vigilance and fear side of what these compounds do. Splitting it out of the limbic system matters because threat processing and reward processing sit in the same blob otherwise, and compounds pull them in opposite directions.

Bed Nucleus of the Stria Terminalis

The structure behind sustained, undirected dread, as opposed to the sharp fear the amygdala produces. It matters here because the anxiety reported after a cycle is usually the slow kind with no object, which is this structure.

HPA Axis Activity

The stress axis: hypothalamus to pituitary to adrenal cortex, ending in cortisol. Relevant to mood twice over. A compound that blocks the glucocorticoid receptor removes the brake the axis runs on, and a compound that shuts down the gonadal axis leaves this one carrying more of the load.

Insular Cortex

Where the body's internal state is read and turned into a feeling. Palpitations, breathlessness and a sense that something is physically wrong are assembled here, which is why cardiovascular strain from these compounds often presents first as anxiety.

Locus Coeruleus

The brain's noradrenaline source and its arousal dial. It sets how alert, how startled and how awake the person is, which is why compounds that raise sympathetic drive cost sleep before they cost anything else.

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.

GABA Signalling

The brain's main inhibitory signal, and the channel that alcohol, benzodiazepines and the neurosteroid allopregnanolone all act on. Anabolic steroids act on it directly too, at a site that overlaps the benzodiazepine site, which is a route to mental effects that has nothing to do with the androgen receptor.

GABA-A Receptor

The brain's main calming channel. Some androgen metabolites sit on it as neurosteroids and change anxiety and sleep quality without touching the androgen receptor at all.