Cocaine crash
Key myth to discard
“Cocaine crash is just dopamine depletion.” This is wrong. The mechanism is more complex and multi-component.
Primary crash mechanism: D2 autoreceptor-mediated vesicular redistribution
- Acute cocaine → massive extracellular DA/NE/5-HT accumulation
- Sustained D2 autoreceptor activation → vesicles redistribute away from synaptosomal release sites (not simple depletion — still present, just in wrong location)
- Next depolarisation → much less DA released per nerve firing → functional deficit even with normal vesicular stores
- PKC-mediated DAT dysregulation: cocaine blocks PKC phosphorylation of DAT → DAT levels stay high → pulls DA out of synapse faster during recovery → prolongs the low-DA state
HPA axis disruption
- Acute use: potent HPA activator → ↑ ACTH and cortisol
- Withdrawal: paradoxical HPA suppression + lost glucocorticoid negative feedback (allostatic load from chronic activation)
- Chronic/abstinent: stress-induced cortisol responses are sensitised → predict relapse (JAMA Psychiatry 2006)
- Cortisol elevation during acute use, but blunted HPA responses during withdrawal
Neuroinflammation (TLR4/NF-κB/NLRP3)
- Cocaine activates microglia and astrocytes via TLR4 receptor
- Induces TNF-α, IL-1β, IL-6, CCL-2 via NF-κB and NLRP3 inflammasome pathways (PMC6393223)
- Elevated peripheral TNF-α in cocaine-dependent individuals
- Inflammation persists 10+ days into abstinence — conditioned cues STILL elevate TNF-α and reduce anti-inflammatory IL-10 even after 10 days of physical withdrawal (PMC3674778)
- Cytokines bidirectionally sensitise HPA axis AND are propagated by it → feedforward loop; directly modulate dopamine system → produce anhedonia
D2 Receptor Recovery Timeline (PET Data)
| Timeframe | D2/D3 Status | Evidence |
|---|---|---|
| Acute (hours-days) | ↓ ~20% availability | Primate PET |
| 1 week abstinence | Still reduced | Human PET (PMC3760378) |
| 9 months (primate) | Still NOT recovered | PubMed 37349473 |
| Sustained abstinence (human) | Normalised | Human PET (likely survivor bias — only successful abstainers scanned) |
Anhedonia timeline: single session → hours to 2–3 days; binge → days to 1–2 weeks; chronic → weeks to months; correlates with D2R downregulation. Anhedonia >3 weeks associated with high relapse risk.
Anhedonia timeline
| Context | Duration |
|---|---|
| Single session | Hours to 2–3 days |
| Binge | Days to 1–2 weeks |
| Chronic | Weeks to months; correlates with D2R downregulation |
D2 receptor recovery
- D2R downregulation persisted 9 months in primates (no recovery)
- Human data: recovered users (sustained abstinence) show normal D2R levels
- Likely selection bias in human studies (only successful abstainers get scanned)
- Chronic use → likely very long recovery even if possible
Related
Cocaine, DAT blockade, Cardiovascular signatures, Cocaine sleep architecture, Cocaine risk profile