Memory Consolidation

Hippocampus

Where new memory is laid down. Unusually sensitive to sustained cortisol and to lost deep sleep, both of which these compounds can produce, which makes it the structure behind most reported memory complaints.

Adult Neurogenesis

The birth of new neurons in the adult brain, effectively confined to the dentate gyrus. It is suppressed by sustained cortisol and by lost deep sleep, both of which these compounds produce, and it is one of the few brain processes that recovers when the insult stops.

Dentate Gyrus

The one part of the adult human brain where new neurons are reliably born. It sits at the entrance to the hippocampus, which is why anything that suppresses neurogenesis shows up first as a memory complaint.

Local Brain Estrogen Synthesis

The brain makes its own estradiol from testosterone, in neurons and astrocytes, independently of what the testes supply. This single fact is why a blood estradiol reading does not tell you what the brain has, and why an aromatase inhibitor is a different kind of intervention from simply having low testosterone.

Sleep Quality

How restorative sleep is, as opposed to how much of it there is. Deep and REM sleep are where growth hormone is released and where memory is consolidated, so this is the measure that connects a sleep effect to a memory effect. A person can sleep eight hours and get almost none of this.

Verbal Memory

Recall of words, names and conversation. Studied in testosterone trials in older men with mixed and generally small results, which is worth stating plainly: this is one of the few cognitive measures here with any controlled human data at all, and the data does not show a large effect.