Definition and Diagnosis
Dementia, termed major neurocognitive disorder in DSM-5-TR, is an acquired, progressive decline in one or more cognitive domains, such as memory, language, executive function, or visuospatial ability, that is severe enough to interfere with independence in everyday activities.
Epidemiology
Prevalence rises sharply with age, affecting a small proportion of people in their sixties but a substantial proportion of those over 85. Alzheimer's disease is the most common cause, followed by vascular, Lewy body, and frontotemporal dementia, with global prevalence expected to rise considerably as populations age.
Risk Factors
Risk factors include advancing age, family history and genetic factors (such as the APOE-e4 allele in Alzheimer's disease), cardiovascular risk factors including hypertension and diabetes, low educational attainment, hearing loss, social isolation, and prior traumatic brain injury.
Symptoms and Subtypes
Presentation depends on the underlying cause but commonly includes progressive memory loss, difficulty with language or word-finding, impaired judgment and problem-solving, disorientation, and personality or behavioral changes. Later stages often involve loss of ability to perform basic self-care.
Diagnosis
Diagnosis involves detailed cognitive testing, collateral history from family members, and neuroimaging to assess structural changes and exclude reversible causes such as normal-pressure hydrocephalus, vitamin deficiencies, or thyroid dysfunction. Specific biomarkers and neuropsychological profiles help distinguish the underlying subtype.
Treatment
Management is largely supportive and multidisciplinary, involving cholinesterase inhibitors or memantine for symptomatic benefit in Alzheimer's disease, treatment of behavioral and psychiatric symptoms, caregiver support and education, and optimization of cardiovascular risk factors. Newer disease-modifying antibody therapies are available for early Alzheimer's disease in some settings.
Prognosis
Dementia is generally progressive and irreversible, with a course that varies by subtype but typically leads to increasing dependency over years. Early diagnosis and comprehensive care planning improve quality of life for both patients and caregivers, even though the underlying decline cannot currently be reversed.
Reference
Sadock, B. J., Sadock, V. A., & Ruiz, P. Kaplan & Sadock's Synopsis of Psychiatry (11th ed.); American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.).