Normal Cerebral Perfusion and Intact Working Memory
Baseline reference: full blood flow, sharp memory, quick processing.
- 100%: Cerebral blood flow (normal resting perfusion)
- 7 items: Working memory span (typical adult capacity)
- ~430 ms: Reaction time (simple cognitive task)
- None: Neuroinflammation (no microglial activation)
Healthy cortical blood supply
Dense, evenly distributed particle flow across cortex.
Intact working-memory circuits
Grid task completed quickly with full accuracy.
Post-Infection Microglial Activation and Cytokine Signaling
Infection triggers glial activation and inflammatory markers in brain tissue.
- Elevated: Microglial activation (PET/TSPO imaging studies)
- IL-6, TNF-α: Cytokine markers (commonly reported elevated)
- 2–8 wks: Onset window (post acute infection)
- Frontal, parietal: Affected regions (memory/attention networks)
Glial activation after viral infection
Immune signaling spreads through cortical support cells.
Early metabolic and vascular stress
Inflamed tissue strains nearby microvascular blood supply.
Reduced Cortical Blood Flow on Functional Imaging
Blood flow thins in cortex regions driving memory and speed.
- up to −35%: CBF reduction (severe) (relative to normal)
- ASL-MRI, SPECT: Imaging modality (perfusion studies used)
- Frontal, parietal: Most affected lobes (working-memory circuitry)
- Strong: Symptom correlation (hypoperfusion tracks fog severity)
Perfusion thinning across cortical bands
Particle density fades where inflammation glow is strongest.
Vascular-neural coupling breakdown
Reduced flow limits oxygen and glucose delivery.
Measurable Deficits in Speed, Memory, and Attention
Standardized testing reveals slower, less accurate cognitive performance.
- up to +380 ms: Reaction time increase (severe cases)
- up to −3 items: Working memory drop (vs. baseline span)
- Impaired: Sustained attention (longer tasks show decline)
- N-back, CPT: Common test tools (used in long COVID studies)
Working-memory grid task performance
Fewer cells recalled correctly as inflammation rises.
Slower processing speed under load
Reaction-time bar shifts from green toward red.
Gradual Recovery Over Months, With a Persisting Subset
Most patients improve steadily; a minority stay symptomatic longer.
- 3–9 months: Typical recovery window (mild–moderate cases)
- Majority: Full resolution (of mild/moderate presentations)
- Subset: Persistent symptoms (especially severe presentations)
- Inflammation resolution: Key driver of recovery (tracks with CBF normalization)
Recovery trajectory by severity
Slide months forward to watch metrics normalize.
Why some cases persist
Severe inflammation resolves slower and less completely.