Metabolic causes of altered mental status affect both sides of the brain equally and result in physical findings that are generally bilateral and diffuse rather than one-sided and localized. External problems include poisoning from contaminated food or overdoses of alcohol or drugs, which can cause difficulty walking, blurred vision, slurred speech, and impaired memory. Environmental and infectious internal problems involve organisms like bacteria and viruses invading the central nervous system. Other internal problems are respiratory or circulatory conditions that result in hypoxia or hypoperfusion, low blood sugar, or the buildup of toxic substances due to liver or kidney failure.