Dementies

Dementies are a group of brain disorders characterized by a progressive decline in memory and other cognitive functions, severe enough to interfere with daily life. They result from neurodegenerative diseases or brain injury and are not a normal part of aging. Dementias differ from delirium, which is acute and fluctuating, and from milder forms of cognitive impairment that may precede dementia.

The most common causes include Alzheimer's disease, followed by vascular dementia, Lewy body dementia, and frontotemporal dementia. Mixed dementia—where more than one type occurs together—is also common in older adults. Less frequent forms include prion diseases, Huntington's disease, and rarer genetic syndromes. Some conditions with dementia-like symptoms, such as certain vitamin deficiencies or thyroid disorders, can be treatable and reversible with appropriate care.

Typical symptoms begin with memory loss and difficulties with language or problem solving, and may progress to impaired reasoning, visuospatial skills, and changes in behavior or personality. Diagnosis relies on clinical history and cognitive testing, supported by brain imaging and laboratory tests to exclude other causes. In specialized centers, biomarkers may aid in identifying Alzheimer’s pathology.

There is no cure for most dementias. Treatments aim to slow progression and relieve symptoms. Some medications, such as cholinesterase inhibitors and memantine, can help certain patients with Alzheimer's disease. Nonpharmacological strategies—cognitive stimulation, physical activity, social engagement—and comprehensive caregiver support are important components of care. Planning for safety and future care is often necessary.

Dementias are typically progressive, with duration ranging from several years to over a decade. Prevalence increases with age, making the global burden substantial. Risk factors include age, family history, cardiovascular disease, diabetes, and head injury. Prevention focuses on cardiovascular risk management, healthy lifestyle choices, and early medical evaluation of cognitive changes.