Clinical Vignette
Patient: "Mr. X," 68-year-old retired firefighter, referred 6 months after a stroke with cognitive decline that his wife describes as different from 'normal aging.'
Chief Concern: Wife: "Since his stroke 6 months ago, he can't plan anything. He was always so organized — now he can't follow a recipe, can't manage his medications, and gets confused when given multiple instructions. His thinking seems to have dropped off a cliff."
History of Present Illness: Mr. X suffered a left middle cerebral artery ischemic stroke 6 months ago. Acute deficits included right-sided weakness (resolved with thrombolysis) and expressive aphasia (partially resolved). Post-stroke cognitive assessment reveals: (1) Executive dysfunction: cannot sequence multi-step tasks (recipe following, medication management), impaired planning, difficulty with set-shifting. (2) Processing speed: markedly slowed (takes 3-4x longer for routine tasks). (3) Attention: reduced sustained attention, difficulty filtering distractions. (4) Memory: relatively preserved (can learn new information but retrieval is slow). (5) Language: residual word-finding difficulties. His wife reports that his cognition was NORMAL before the stroke (no prior concerns about memory or thinking). The decline was ABRUPT (coinciding with the stroke) rather than gradual. MRI brain: left MCA territory infarct with additional white matter hyperintensities bilaterally (small vessel disease). He has significant vascular risk factors: hypertension (poorly controlled), diabetes mellitus type 2, hyperlipidemia, smoking (40 pack-years, quit 5 years ago).
Medical History: Left MCA ischemic stroke (6 months ago). Hypertension (poorly controlled). Diabetes mellitus type 2. Hyperlipidemia. Former smoker (40 pack-years).
Mental Status Exam: Alert, cooperative. Speech mildly dysfluent (residual aphasia). Processing notably slow. Right hand slightly weak. Mood 'frustrated.' Trail Making A: impaired (slowed). Trail Making B: severely impaired (executive dysfunction). Digit Span: forward 6 (normal), backward 3 (impaired — working memory). Delayed recall: 2/3 (mild impairment but better than expected for AD). Clock Drawing: poor (executive, not constructional). MMSE 21/30.
Step 1: Vascular NCD DSM-5-TR Criteria
Major NCD criteria met:
Significant cognitive decline from premorbid level. Multiple domains impaired (executive, processing speed, attention). Loss of functional independence (medication management, cooking). Not delirium. Not better explained by another mental disorder. MET.
Vascular etiology: Clinical features consistent with vascular etiology.
(1) Temporal relationship: cognitive decline coincided with stroke (abrupt onset). (2) Prominent executive dysfunction and processing speed slowing (characteristic of vascular pathology). (3) Memory relatively preserved (unlike Alzheimer's pattern). MET.
Vascular etiology: Neuroimaging evidence of cerebrovascular disease.
MRI: Left MCA territory infarct + bilateral white matter hyperintensities (small vessel disease). Both large vessel (stroke) and small vessel disease present. MET — NEUROIMAGING CONFIRMED.
Classification: PROBABLE vascular NCD (temporal + neuroimaging + clinical pattern).
Temporal relationship established. Neuroimaging confirms vascular pathology. Clinical pattern consistent with vascular etiology. PROBABLE VASCULAR NCD.
Step 2: Vascular vs. Alzheimer's Pattern
| Feature | Vascular NCD | Alzheimer's NCD | This Patient |
|---|---|---|---|
| Onset | Abrupt (post-stroke) or stepwise | Insidious and gradual | Vascular: abrupt, coinciding with stroke |
| Course | Stepwise (decline with each event) or static | Steadily progressive | Abrupt decline → relative plateau |
| Predominant deficit | Executive function, processing speed | Memory (learning and recall) | Executive and processing speed |
| Memory | Relatively preserved (retrieval deficit > encoding deficit) | Severely impaired (encoding deficit) | Relatively preserved |
| Neuroimaging | Infarcts, white matter changes, lacunes | Hippocampal atrophy | MCA infarct + WMH |
| Vascular risk factors | Present (HTN, DM, smoking, dyslipidemia) | Age is primary risk | Multiple: HTN, DM, smoking, dyslipidemia |
Secondary Prevention
Aggressive vascular risk factor management is the PRIMARY treatment for vascular NCD. Preventing further cerebrovascular events is the most effective strategy for preventing further cognitive decline. Antiplatelet therapy, statin, antihypertensive optimization, and diabetes control are all indicated.
Diagnostic Formulation
Diagnostic Conclusion
Major Neurocognitive Disorder, Probable Vascular Etiology (F01.50): Major NCD criteria met. Vascular etiology confirmed by temporal relationship to stroke, neuroimaging (MCA infarct + small vessel disease), and clinical pattern (executive/processing speed predominant, memory relatively preserved). Treatment: (1) Aggressive secondary stroke prevention (antiplatelet, statin, antihypertensive optimization, diabetes management). (2) Cognitive rehabilitation (targeting executive function, attention, processing speed). (3) Occupational therapy for adaptive strategies. (4) Cholinesterase inhibitor if mixed pathology (vascular + Alzheimer's) is suspected.
Teaching Points
- Vascular NCD is the second most common cause of major NCD after Alzheimer's disease, and mixed pathology (vascular + Alzheimer's) is common in elderly patients. When mixed pathology is suspected, both etiological subtypes should be diagnosed.
- The cognitive profile of vascular NCD differs from Alzheimer's: vascular NCD characteristically impairs EXECUTIVE FUNCTION and PROCESSING SPEED, while memory is relatively preserved early. Alzheimer's characteristically impairs MEMORY (learning/encoding) first, with executive dysfunction emerging later.
- Three patterns of vascular NCD: (1) Post-stroke: abrupt decline coinciding with a stroke (Mr. X). (2) Multi-infarct: stepwise decline with each vascular event. (3) Small vessel/subcortical: gradual decline due to chronic cerebral small vessel disease (white matter hyperintensities, lacunar infarcts).
- Secondary stroke prevention IS the primary treatment for vascular NCD. Unlike Alzheimer's (where treatment options are limited), vascular NCD can be PREVENTED from worsening by aggressively managing the underlying vascular risk factors. Every prevented stroke is a prevented cognitive decline step.
- Cholinesterase inhibitors have a smaller effect in pure vascular NCD compared to Alzheimer's but may benefit patients with mixed pathology. The decision to use cholinesterase inhibitors in vascular NCD should consider the likelihood of concurrent Alzheimer's pathology.