APA Dictionary of Psychology

a neurotoxic protein, produced by the bacterium Clostridium botulinum, that is the most acutely lethal biological substance yet identified. It causes paralysis by binding to nerve endings where they connect with muscles. Despite its toxicity, small amounts of commercially developed varieties (e.g., those marketed under the brand name Botox), when correctly administered via injection by a trained medical professional, are used in numerous health and cosmetic interventions. Examples include the treatment of trigeminal neuralgia, various types of dystonia, muscle spasms caused by cerebral palsy, drooling caused by Parkinson’s disease, and facial wrinkles. The toxin’s easing of pain, muscle spasms, and dystonias can also lead to a reduction in the depression experienced as a result of the stress of living with these medical conditions. However, if the toxin spreads, it can cause paralysis in the wrong muscle group or botulism, a systemic and potentially fatal infection.