The Biology of Focus, Memory and Brain Fog

Attention networks

Cognitive neuroscience distinguishes an alerting network, an orienting network and an executive control network. They rely on different transmitter systems — noradrenaline, acetylcholine and dopamine respectively — which is why a compound can improve one aspect of attention while leaving another untouched.

Working memory

Working memory depends on sustained firing in prefrontal circuits, and its relationship with dopamine follows an inverted-U curve: too little and the signal is unstable, too much and it becomes inflexible. Optimal is a narrow band, which is why more stimulation is not reliably better.

What 'brain fog' usually is

The term has no clinical definition. In practice it collects together sleep debt, systemic inflammation, thyroid and metabolic disturbance, dehydration, medication effects and mood disorders — all of which produce overlapping subjective symptoms.

That heterogeneity is precisely why research on cognitive compounds is difficult: the same complaint in two subjects can have entirely different physiology behind it.

Neurotrophic signalling

Brain-derived neurotrophic factor supports synaptic plasticity and is one of the most frequently measured endpoints in cognitive peptide studies, including work on Semax. Its expression responds to exercise, sleep and metabolic state as well, which makes it a noisy endpoint without tight controls.