Substance use significantly contributes to cognitive decline, impairing memory, attention, and decision-making abilities. Chronic use of drugs or alcohol damages neural pathways, accelerates brain aging, and may lead to conditions like dementia. Substances such as opioids, stimulants, or alcohol are particularly harmful, causing irreversible damage when used long-term. Early intervention and cessation are crucial to halt further deterioration. Cognitive rehabilitation programs, brain-healthy diets, and regular mental exercises can help restore function. By prioritizing brain health in addiction recovery plans, individuals can improve their quality of life and reduce the risk of severe cognitive disorders.