ACTH 4-10

acth/" class="wiki-internal-link">ACTH 4-10 contains the sequence His-Phe-Arg-Trp, which is critical for alpha-msh/" class="wiki-internal-link">melanocortin receptor binding. In the brain, activation of MC3R and MC4R in hippocampus, prefrontal cortex, and attention-related circuits modulates synaptic plasticity, attentional gating, and memory consolidation. Unlike full ACTH, the fragment lacks the sequences responsible for corticotropic activity, dissociating cognitive effects from adrenal stimulation.

Central melanocortin receptor activation is associated with enhanced vigilance, improved sustained attention, and better performance on tasks requiring focused concentration. ACTH 4-10 is thought to modulate dopaminergic and noradrenergic circuits in prefrontal attention networks, providing cognitive benefits consistent with melanocortin receptor stimulation without direct monoamine effects.

Controlled human studies from the 1970s-1990s showed intranasal or subcutaneous ACTH 4-10 improved performance on selective attention tasks, visual memory tests, and learning consolidation trials. Effects were mild to moderate and most consistent in subjects with attention deficits or age-related cognitive decline.

Pilot studies in children with attention difficulties suggested ACTH 4-10 improved sustained attention without the side effects of classical stimulants. This line of research was not pursued to full clinical development but remains a reference point for non-stimulant cognitive enhancement.