Cognitive function may be affected by all of the following except:

• A. Dehydration
• B. Malnutrition
• C. Abnormal body temperature
• D. Depression

Answer: (D)

Cognitive function is most directly affected by the brain’s immediate environment. Dehydration lowers cerebral blood flow and disrupts electrolyte balance, which can cause confusion and slower thinking. Malnutrition deprives the brain of glucose and essential nutrients needed for mental work, leading to fatigue and reduced concentration. Abnormal body temperature disrupts metabolic processes and neural signaling, potentially causing delirium or cognitive slowing. Depression, while it can influence concentration and memory, is a mood disorder rather than a direct acute physiological disruption to the brain’s environment. In this context, it’s considered the exception because the other factors are immediate physiological changes that acutely impact cognition.