ADHD overwhelm happens when the cognitive load on a working memory system with lower capacity exceeds what the prefrontal cortex can sort and prioritize. The result is shutdown: every task feels equally urgent, decisions become impossible, and the body freezes. This guide covers the neurological mechanism, five early warning signs, and five evidence-based strategies — brain dumping, single-priority focus, body-doubling, environment changes, and physical first actions — to break the loop.