Clinical Vignette
Patient: "Mrs. C," 74-year-old retired teacher, brought by her daughter who noticed progressively worsening memory and functioning over 18 months.
Chief Concern: Daughter: "Mom keeps forgetting conversations we had minutes ago. She got lost driving to the grocery store she's been going to for 30 years. She left the stove on twice. I found expired food in the fridge she didn't realize was old. She used to manage everything perfectly."
History of Present Illness: Mrs. C has demonstrated progressive cognitive decline over 18 months, initially noticed by her daughter as 'repeating herself.' The decline has been insidious and gradual. Current symptoms include: (1) Memory: forgets recent conversations within minutes, asks the same questions repeatedly, loses personal items daily, forgot a close friend's funeral. (2) Executive function: unable to manage her finances (bills unpaid for 3 months, checkbook errors), difficulty following recipes she has used for 40 years. (3) Visuospatial: got lost driving a familiar route, difficulty parking. (4) Language: occasional word-finding difficulties ('tip of the tongue'). (5) Social cognition: intact (maintains appropriate social behavior). She previously managed all household finances, cooked elaborate meals, and drove independently. Her daughter has now taken over finances, accompanies her to appointments, and supervises cooking. Mrs. C minimizes her difficulties: 'Everyone gets forgetful at my age.' She has no depression (maintains interest in activities, sleep is normal, appetite normal, no guilt or worthlessness).
Medical History: Hypertension (controlled). Hyperlipidemia. No diabetes. No history of stroke or TBI. No recent medication changes.
Mental Status Exam: Pleasant, cooperative. Personal hygiene maintained (daughter assists). Speech fluent with occasional word-finding pauses. Mood 'fine.' Affect appropriate. MMSE: 20/30 (lost points: delayed recall 0/3, serial 7s 2/5, copy intersecting pentagons failed, date incorrect). Clock drawing: attempted but numbers placed incorrectly (spatial disorganization). MoCA: 17/30. No psychotic symptoms. No depression. Insight partially impaired: acknowledges some 'forgetfulness' but minimizes severity.
Step 1: Major NCD DSM-5-TR Criteria
Criterion A: Evidence of significant cognitive decline from a previous level of performance in ≥1 cognitive domain (complex attention, executive function, learning/memory, language, perceptual-motor, social cognition) based on: (1) concern of the individual, an informant, or the clinician; AND (2) substantial impairment in cognitive performance, preferably documented by standardized testing.
(1) Daughter reports progressive decline. Clinician observes deficits. (2) MMSE 20/30, MoCA 17/30 (both below cutoffs). Deficits in: learning/memory (0/3 delayed recall), executive function (finance errors, recipe difficulty), perceptual-motor (lost driving, clock drawing impaired), and language (word-finding). MET — MULTIPLE DOMAINS.
Criterion B: Cognitive deficits interfere with independence in everyday activities.
Can no longer manage finances (daughter took over). Cannot drive safely. Requires cooking supervision. Cannot manage medications independently. These represent a loss of independence from a prior level of function. MET — LOSS OF INDEPENDENCE.
Criterion C: Not occurring exclusively in the context of delirium.
Symptoms are chronic (18 months), progressive, and consistent. Not fluctuating. No acute onset. No altered level of consciousness. MET.
Criterion D: Not better explained by another mental disorder (e.g., MDD, schizophrenia).
No depression (normal sleep, appetite, interest, energy, no guilt). No psychotic symptoms. No substance use disorder. Cognitive decline is the primary and sole process. MET.
Step 2: Evidence for Alzheimer's Etiology
DSM-5-TR specifies etiological subtypes. Alzheimer's disease is the most common cause of Major NCD in the elderly:
| Feature | Probable Alzheimer's | Vascular NCD | Lewy Body NCD | This Patient |
|---|---|---|---|---|
| Onset | Insidious, gradual | Stepwise, post-stroke | Fluctuating cognition | Alzheimer's: insidious over 18 months |
| Predominant domain | Memory (learning and recall) | Executive function, processing speed | Visual hallucinations, attention fluctuations | Alzheimer's: memory is most impaired |
| Course | Steadily progressive | Stepwise or static | Fluctuating | Steadily progressive |
| Motor features | Absent early | May have focal deficits | Parkinsonism | Absent |
| Hallucinations | Late if present | Uncommon | Early visual hallucinations (core feature) | Absent |
Probable Alzheimer's Disease
Insidious onset, gradual progression, memory-predominant pattern, absence of vascular risk events, absence of fluctuation, and absence of motor features support Alzheimer's as the etiological subtype. Classification: Major NCD due to Probable Alzheimer's Disease.
Diagnostic Formulation
Diagnostic Conclusion
Major Neurocognitive Disorder due to Probable Alzheimer's Disease (G30.9 + F02.80): All DSM-5-TR criteria for Major NCD met. Etiological subtype: probable Alzheimer's disease (insidious onset, progressive memory decline, no alternative etiology). Multiple cognitive domains impaired. Loss of functional independence. Treatment: (1) Cholinesterase inhibitor (donepezil 5-10mg) for symptomatic management. (2) Caregiver support and education (disease trajectory, care planning, caregiver burnout prevention). (3) Safety planning (driving cessation, stove safety, medication management). (4) Advance care planning (while patient retains partial capacity). (5) Structural neuroimaging (MRI) to evaluate hippocampal atrophy and exclude reversible causes.
Teaching Points
- DSM-5-TR replaced 'Dementia' with 'Major Neurocognitive Disorder' to reduce stigma and emphasize the syndrome rather than a specific disease. Major NCD is the syndrome (significant cognitive decline + loss of independence). Alzheimer's disease is one of many possible etiologies.
- The distinction between Major NCD (formerly dementia) and Mild NCD (formerly MCI) is FUNCTIONAL INDEPENDENCE. Major NCD requires cognitive decline that INTERFERES with independence (Criterion B). Mild NCD involves cognitive decline that does NOT yet interfere with independence (adaptive functioning preserved, possibly with greater effort or compensatory strategies).
- Reversible causes of cognitive decline must be excluded before diagnosing Alzheimer's: hypothyroidism (TSH), vitamin B12 deficiency, normal pressure hydrocephalus (gait/urinary/cognitive triad), medication-related (anticholinergics, benzodiazepines), and depression ('pseudodementia'). Mrs. C shows no depression, which is an important distinction.
- Cholinesterase inhibitors (donepezil, rivastigmine, galantamine) provide modest symptomatic benefit in Alzheimer's disease. They do NOT modify the disease course. Patients and families must understand this: the medications may slow functional decline temporarily but do not cure or halt the underlying neurodegenerative process.
- Caregiver burnout is a significant clinical concern in Alzheimer's care. Caregivers of Alzheimer's patients have higher rates of depression, anxiety, and physical health problems. Clinicians should assess caregiver well-being at every visit and provide referrals to respite care, support groups, and community resources.