Dementia

Chronic cognitive syndrome marked by progressive decline in one or more cognitive domains (memory, language, executive function, etc.) severe enough to impair daily life. It is an umbrella term for multiple brain diseases (most commonly Alzheimer's disease accounting for ~60–70%) that cause long-term cognitive and functional decline.

• Dementia is common and impactful: ~10% of people over 65 (and ~30–50% over 85) are affected. It is a leading cause of disability in older adults and a major public health burden. Early recognition is critical for management, caregiver planning, and identifying reversible causes. Dementia syndromes frequently appear on board exams in contexts of memory loss, elder care, and neurodegenerative disease.

• Alzheimer disease (AD) – Gradual onset in elderly (typically >65). Prominent short-term memory loss (repeating questions, misplacing items), with progression to disorientation and word-finding difficulty. No focal neurologic deficits early. Pathology: diffuse cortical atrophy (especially hippocampal), extracellular β-amyloid plaques and intraneuronal tau tangles.
• Vascular dementia – Cognitive decline from cerebrovascular disease. Often a stepwise deterioration with each stroke or infarct. Patients may have focal neurologic signs (e.g., hemiparesis, gait disturbance) and history of stroke or risk factors (hypertension, diabetes). Imaging classically shows multiple infarcts or extensive white matter lesions.
• Dementia with Lewy bodies (DLB) – Fluctuating cognition and early hallucinations (vivid visual hallucinations) plus parkinsonian motor features. REM sleep behavior disorder (dream-enacting sleep) is common. Sensitive to antipsychotics (can worsen parkinsonism). Pathology: widespread Lewy bodies (α-synuclein aggregates) in cortex and brainstem.
• Frontotemporal dementia (FTD) – Degeneration of frontal ± temporal lobes; often onset in 50s–60s. Presents with personality and behavior changes (apathy, disinhibition, socially inappropriate behavior) or progressive language difficulties (primary aphasia). Memory is relatively spared early. Pathology varies (e.g., tau-containing Pick bodies or ubiquitinated TDP-43 protein aggregates in affected lobes).

1. Confirm a chronic cognitive decline (months to years) interfering with daily function (distinguish from acute delirium or mild cognitive impairment). Use a brief cognitive screening test (e.g., MMSE, MoCA) to objectify deficits.
2. Evaluate reversible causes and contributing factors: obtain labs (especially vitamin B12, TSH, also metabolic panel, CBC) and screen for depression; review medications (stop anticholinergics or sedatives that may worsen cognition).
3. Perform neuroimaging (usually MRI brain) in new-onset dementia to rule out structural lesions (stroke, tumor, normal pressure hydrocephalus). MRI can also support a subtype (e.g., multiple infarcts in vascular dementia, disproportionate hippocampal atrophy in AD). Consider EEG if seizures or Creutzfeldt-Jakob disease are suspected.
4. Differentiate dementia subtypes clinically: e.g., evidence of strokes or stepwise decline suggests vascular dementia; visual hallucinations and fluctuating alertness suggest Lewy body dementia; early personality change suggests frontotemporal dementia. Additional testing (neuropsychological evaluation, PET/SPECT scans, CSF biomarkers) may be used in uncertain cases.
5. Address safety and planning: ensure patients are supervised if needed (cooking, driving cessation if unsafe, fall precautions). Engage family/caregivers in care planning, advance directives, and provide education/support resources.

1. Non-pharmacologic: family and caregiver support, establish a daily routine, cognitive stimulation activities, and ensure a safe environment (supervise cooking, driving cessation if needed). Treat modifiable risk factors (manage hypertension, diabetes, etc. to slow vascular contributions). Address comorbid depression or insomnia (therapy, sleep hygiene).
2. Pharmacologic: Cholinesterase inhibitors (donepezil, rivastigmine, galantamine) are first-line for Alzheimer's (they may also provide some benefit in Lewy body dementia). Memantine (NMDA antagonist) is added in moderate-to-severe AD. Vascular dementia management focuses on stroke prevention (aspirin, treat risk factors). SSRIs can help mood or behavioral symptoms; avoid anticholinergic drugs (worsen cognition).
3. For agitation or psychosis, use environmental interventions first. If severe, consider low-dose atypical antipsychotics, but use caution (especially in Lewy body dementia, due to severe sensitivity to neuroleptics). Note that all antipsychotics in dementia carry an FDA warning for increased mortality in elderly patients.

• Remember reversible causes of dementia with DEMENTIA: Drugs (anticholinergics, etc.), Emotional (depression), Metabolic (B12, thyroid), Eyes/Ears (sensory deficits), Normal pressure hydrocephalus, Tumor, Infection (HIV, syphilis), Alcohol abuse.
• Normal pressure hydrocephalus presents with the 'wet, wacky, wobbly' triad – unlike degenerative dementias, this can be treated (ventriculoperitoneal shunt) to improve cognition.
• Lewy body vs Parkinson disease dementia: apply the one-year rule – if cognitive symptoms begin before or within 1 year of parkinsonian motor onset, it's DLB; if dementia develops >1 year after established Parkinson's, it's Parkinson disease dementia.

• Rapidly progressive dementia (weeks to months) with motor signs (e.g., myoclonus, ataxia) – suspect prion disease such as Creutzfeldt-Jakob disease and pursue prompt evaluation (e.g., EEG, CSF 14-3-3).
• New or acute mental status change in a patient with known dementia – consider superimposed delirium (e.g., infection, medication) rather than just progression of dementia, and investigate the underlying cause urgently.

1. Patient with memory complaints or cognitive concern → Perform brief cognitive screening (MMSE or MoCA) and assess daily functioning (ADLs/IADLs) to confirm if criteria for dementia are met.
2. If dementia suspected → Order laboratory tests (B12, TSH, metabolic panel, CBC, etc.) to rule out reversible causes; screen for depression and review medications.
3. Obtain brain imaging (MRI preferred) to evaluate for strokes, tumors, hydrocephalus, or other structural lesions.
4. Differentiate dementia subtype by clinical clues: history of strokes or vascular risk factors (vascular dementia); hallucinations & parkinsonism (Lewy body); early behavior change (frontotemporal); etc. Consider referral for neuropsychological testing or specialist consult if uncertain.
5. Initiate management: provide patient and caregiver education, implement safety measures and support services, start cognitive enhancers or other appropriate medications based on subtype, and schedule regular follow-up to monitor progression and adjust care.

• Elderly patient with insidious memory loss (gets lost driving, repeats questions) over several years, no focal deficits, and MRI showing diffuse cortical and hippocampal atrophy → Alzheimer disease.
• Older patient with history of multiple strokes who has stepwise worsening of cognition and focal neurologic signs (e.g., pronator drift, hyperreflexia) → Vascular dementia.
• Visual hallucinations in an older patient with dementia and parkinsonian gait, along with fluctuating alertness → Dementia with Lewy bodies.
• A 55-year-old with progressive change in personality and social conduct (apathy, disinhibition) and later difficulty with executive tasks or language, with MRI revealing focal frontal lobe atrophy → Frontotemporal dementia.