A study in newborn mice found that giving the immune‑boosting peptide thymosin‑alpha‑1 under the skin helped the kids’ brains grow more new cells and improved their learning later on, likely because it nudged the immune system toward a Th1‑type response and raised brain‑supporting growth factors. The effect also protected the brain from damage caused by an infection‑mimic. However, the work was done in very young mice, not humans, and no dosing or safety info for people is provided, so it’s not a ready‑to‑use protocol for most biohackers.

In early life, the immune system plays an essential role in brain development. In our study, the immunopotentiator thymosin alpha-1 (Ta1) was peripherally administered to neonatal mice to explore whether the peripheral immunopotentiator affects neurodevelopment and cognition, and to further investigate the relevant mechanism. Compared with the control group, the Ta1 mice displayed better cognitive abilities in early life. The numbers of 5-bromodeoxyuridine (BrdU)+, nestin+, T-box transcription factor 2 (Tbr2)+, BrdU+/doublecortin (DCX)+, BrdU+/ionized calcium-binding adaptor molecule 1 (Iba1)+, and BrdU+/neuronal nuclei (NeuN)+ cells in the hippocampus were increased in the Ta1 group, accompanied by increased interleukin-4 (IL-4), interferon-gamma, brain-derived neurotrophic factor, nerve growth factor, and insulin-like growth factor-1 as well as decreased IL-6 and tumor necrosis factor-α. Furthermore, the Ta1-group showed a Th1-polarized immune response, and the neurotrophic factors were positively associated with the Th1/Th2 ratio. More importantly, administration of Ta1 blocked lipopolysaccharide-induced impairment of hippocampal neurogenesis in early life. These findings suggest that peripheral Ta1 contributes to neurogenesis and cognition probably through a systemic Th1 bias, as well as neuroprotection against LPS infection by Ta1.