The simple idea
Any substance can cause psychiatric symptoms — anxiety, low or high mood, psychosis, disturbed sleep. To tell whether a drug is the cause, follow the timeline:
Ask: what substance, how much, how often, when was the last use, when did symptoms start, and — crucially — *do the symptoms ever happen without the drug, and do they persist after* the drug is gone?
Substance‑induced psychosis vs schizophrenia
- Substance‑induced: tightly tied to the drug in time; tends to settle with abstinence.
- Primary (e.g., schizophrenia): follows its own course, independent of the drug.
| Substance‑induced | Primary (e.g. schizophrenia) | |
|---|---|---|
| Tie to the drug | tightly timed | independent |
| After stopping | tends to settle | follows its own course |
But reality can be layered: someone might use cannabis → develop psychosis → and later develop a lasting schizophrenia‑spectrum illness. So never assume "drugs are involved, therefore it can't be schizophrenia." Heavy, high‑potency cannabis use genuinely raises the risk of psychosis, especially in vulnerable people.
Quick check ✅
- What four timeline questions help decide if a drug caused the symptoms?
- Does "the person uses cannabis" rule out schizophrenia?
Remember this 🌟
Where we're going next → Back to enduring patterns, with the modern view — Concept 46.