This narrative review summarizes current evidence and emerging science on dementia prevention and treatment. Dementia affects 10% of those 65 years or older and 35% of those 90 years or older, with profound cognitive, behavioral, and functional consequences. Preventive measures target modifiable risk factors, though no randomized clinical trial data conclusively confirm that interventions prevent dementia. Alzheimer disease is treated with cholinesterase inhibitors, memantine, and antiamyloid immunomodulators, with the latter modestly slowing cognitive and functional decline in mild cognitive impairment or mild dementia. Behavioral and psychological symptoms of dementia are best managed nonpharmacologically, while psychotropic medications have minimal evidence of efficacy and are associated with increased mortality and falls. Prevention strategies include lifestyle modifications such as diet, exercise, and cognitive stimulation, though evidence is mixed. Cardiovascular risk factors, hearing loss, and sleep disturbances are also linked to dementia risk. Statins and aspirin show limited benefit. Multifactorial interventions, such as the FINGER study, show promise in reducing cognitive decline. New amyloid-targeting drugs, like aducanumab, lecanemab, and donanemab, show some efficacy but carry risks of brain edema and bleeding. These drugs are not yet widely available. For dementia treatment, cholinesterase inhibitors and memantine are commonly used, with some evidence of prolonged time to institutionalization. Antipsychotics and antidepressants are used for behavioral and psychological symptoms but are associated with increased risks of falls and cognitive decline. Nonpharmacological approaches are recommended for managing symptoms. Ongoing trials explore new treatments, including amyloid-targeting therapies, and emphasize the need for early intervention and personalized care. Despite advances, dementia prevention and treatment remain challenging, with a need for further research to improve outcomes.This narrative review summarizes current evidence and emerging science on dementia prevention and treatment. Dementia affects 10% of those 65 years or older and 35% of those 90 years or older, with profound cognitive, behavioral, and functional consequences. Preventive measures target modifiable risk factors, though no randomized clinical trial data conclusively confirm that interventions prevent dementia. Alzheimer disease is treated with cholinesterase inhibitors, memantine, and antiamyloid immunomodulators, with the latter modestly slowing cognitive and functional decline in mild cognitive impairment or mild dementia. Behavioral and psychological symptoms of dementia are best managed nonpharmacologically, while psychotropic medications have minimal evidence of efficacy and are associated with increased mortality and falls. Prevention strategies include lifestyle modifications such as diet, exercise, and cognitive stimulation, though evidence is mixed. Cardiovascular risk factors, hearing loss, and sleep disturbances are also linked to dementia risk. Statins and aspirin show limited benefit. Multifactorial interventions, such as the FINGER study, show promise in reducing cognitive decline. New amyloid-targeting drugs, like aducanumab, lecanemab, and donanemab, show some efficacy but carry risks of brain edema and bleeding. These drugs are not yet widely available. For dementia treatment, cholinesterase inhibitors and memantine are commonly used, with some evidence of prolonged time to institutionalization. Antipsychotics and antidepressants are used for behavioral and psychological symptoms but are associated with increased risks of falls and cognitive decline. Nonpharmacological approaches are recommended for managing symptoms. Ongoing trials explore new treatments, including amyloid-targeting therapies, and emphasize the need for early intervention and personalized care. Despite advances, dementia prevention and treatment remain challenging, with a need for further research to improve outcomes.