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KembaraXtra-Medicine – Alzheimer Disease
Dementia is a syndrome characterized by progressive loss of previously acquired cognitive skills, including memory, language, insight, and judgment. Alzheimer disease (AD) is thought to account for the majority of all cases of dementia. The ICD-10CM codes for Alzheimer disease include G30.0 (Alzheimer disease with early onset), G30.1 (Alzheimer disease with late onset), G30.8 (other Alzheimer disease), and G30.9 (Alzheimer disease, unspecified).
The incidence of Alzheimer disease increases markedly with age, with risk doubling every 5 years after age 65. The Chicago Health and Aging Population study demonstrated an average annual incidence of 2.3% among individuals aged 65 years and older, with Black individuals having a significantly increased risk compared with White individuals. In terms of prevalence, approximately 1 in 9 people (10.7%) aged 65 years or older has Alzheimer dementia. In the United States, an estimated 6.5 million people are affected, including 5% of individuals aged 65–74 years, 13.1% of those aged 75–84 years, and 33.2% of those aged 85 years or older. Additionally, 12%–18% of adults over age 60 are believed to have mild cognitive impairment (MCI). Alzheimer disease affects women more frequently than men, with approximately 4 million women and 2.5 million men affected nationwide.
Clinically, Alzheimer disease most often presents insidiously. A spouse or close family member usually first notices progressive memory impairment rather than the patient. Individuals have difficulty learning and retaining new information, managing complex tasks such as finances, and demonstrate impairments in judgment, reasoning, visuospatial abilities, and orientation, often leading to problems such as getting lost or difficulty driving. Behavioral and personality changes, including apathy and mood disturbances, commonly accompany memory loss, and later stages may involve agitation, delusions, or psychosis. Rare atypical variants include early and severe behavioral changes, focal neurologic findings, parkinsonism, hallucinations, frequent falls, or onset of symptoms at or before 65 years of age.
The diagnosis of Alzheimer disease has evolved with the development of biomarkers that demonstrate Alzheimer pathology in vivo, particularly amyloid beta deposition and pathologic tau accumulation. The National Institute on Aging–Alzheimer’s Association (NIA-AA) criteria, initially published in 2011 and revised in 2018, conceptualize Alzheimer disease as a biologic process rather than solely a clinical syndrome. These criteria define three stages: preclinical Alzheimer disease (biologic evidence without symptoms), MCI due to Alzheimer disease (mild memory impairment without functional decline but with biomarker evidence), and dementia due to Alzheimer disease (cognitive decline with functional impairment and biomarker confirmation). The 2018 framework further introduced the ATN system, defining disease by amyloid (A), tau pathology (T), and neurodegeneration (N). Although biomarkers are not yet routinely used in general clinical practice, they are integral to research and clinical trials.
In routine clinical settings, Alzheimer disease is typically diagnosed using clinical history, neurologic examination, and established criteria such as DSM-5 or NINCDS-ADRDA. Core features include progressive memory loss plus at least one additional cognitive deficit (aphasia, apraxia, agnosia, or executive dysfunction), decline in social or occupational functioning, insidious onset with gradual progression, objective documentation of cognitive loss, and exclusion of alternative causes. Red flags suggesting an alternative diagnosis include age younger than 65 years, fluctuating consciousness, rapid progression over months, prominent early behavioral changes, or focal neurologic findings such as gait disturbance, lateralized weakness, myoclonus, or parkinsonism.
The differential diagnosis of Alzheimer disease is broad and includes other neurodegenerative dementias such as frontotemporal lobar degeneration, dementia with Lewy bodies, Parkinson disease dementia, corticobasal syndrome, progressive supranuclear palsy, limbic-predominant age-related TDP-43 encephalopathy, and primary age-related tauopathy. Nondegenerative conditions include vascular cognitive impairment, depression (pseudodementia), subjective memory complaints, brain tumors, chronic subdural hematoma, infections such as HIV or neurosyphilis, toxic or metabolic encephalopathies, and organ failure–related cognitive impairment.
Evaluation begins with a comprehensive history and physical examination, including careful medication review to identify agents that impair cognition, such as anticholinergics, benzodiazepines, opioids, barbiturates, and neuroleptics. Screening for depression is essential, as it may mimic or coexist with dementia. Cognitive screening tools such as the Mini-Mental State Examination, Mini-Cog, and Montreal Cognitive Assessment are commonly used, while formal neuropsychologic testing is reserved for atypical cases or diagnostic uncertainty. In Alzheimer disease, episodic memory deficits typically appear early, whereas attention is often preserved until later stages.
Laboratory evaluation usually includes complete blood count, serum electrolytes, glucose, renal and liver function tests, thyroid function tests, and vitamin B12 levels, with additional testing guided by clinical context. Neuroimaging, preferably MRI, is used to exclude alternative diagnoses and assess characteristic patterns of neurodegeneration, such as hippocampal atrophy. Amyloid and tau PET imaging may support diagnosis in selected cases but are not diagnostic on their own.
Management of Alzheimer disease incorporates both nonpharmacologic and pharmacologic strategies. Nonpharmacologic care focuses on patient safety, caregiver education, behavioral interventions, and cognitive stimulation. Addressing driving safety, wandering, medication management, and household hazards is essential. Behavioral symptoms such as agitation, repetitive questioning, and social withdrawal often respond to structured routines and environmental modifications. A person-centered, interdisciplinary approach tailored to disease stage improves quality of life for both patients and caregivers.
Pharmacologic treatment is primarily symptomatic. Cholinesterase inhibitors (donepezil, rivastigmine, and galantamine) are approved for mild to moderate Alzheimer disease, with donepezil also approved for severe disease. These agents provide modest cognitive and functional benefits but may cause gastrointestinal effects, bradycardia, and sleep disturbances. Memantine, an NMDA receptor antagonist, is approved for moderate to severe Alzheimer disease. Newer anti-amyloid monoclonal antibodies, such as aducanumab and lecanemab, target amyloid pathology and may modestly slow cognitive decline in early disease but require careful patient selection and monitoring due to safety concerns.
Patients with atypical presentations or complex management needs should be referred to specialists with expertise in dementia care. Ongoing caregiver education and support are critical, as they reduce caregiver burden, delay institutionalization, and improve patient outcomes. Prevention strategies emphasize physical activity, cardiovascular risk factor control, cognitive engagement, healthy diet patterns, and avoidance of tobacco and excessive alcohol use.
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