Since the term biohacking was introduced to the biology community in 2000, many applications have been developed by researchers. Biohacking (or bodyhacking) is equivalent to the term do-it-yourself biology and aims to make biology easily accessible to ordinary people and amateurs. Pioneers in this field reveal the amazing secrets of the body's operating system, called MeatOS, and have done a lot of activities regarding hacking this operating system in order to increase the capabilities of the human body. Lifestyle (changing diet, breathing, regular sleep, relaxation and exercise), changing lifespan, increasing individual capabilities and brain (mind) hacking are among the most important aspects of biohacking (body) in humans. Brain (mind) hacking creates attractive opportunities to create more capabilities in people, but on the other hand, it can cause serious challenges and risks in cognitive neuroscience and biosecurity. Brain-derived neurotrophic factor (BDNF) is known as a key biomarker in brain hacking. This specialized protein promotes neurogenesis (the synthesis of new neurons) and neuroplasticity (the brain’s ability to create new neural pathways). Scientists have called BDNF the brain’s growth miracle, and higher levels of BDNF have been linked to better overall cognitive function and memory. This article provides an overview of the potential of neurohackers to enhance or inhibit brain activity from a biosecurity perspective.