Preview build — content shown here has not yet cleared independent review and is not the public release.
ICD-10 Learning Lab Exit Presentation Mode

Category: F10 F11 F12 F13 F14 F15 F16 F17 F18 F19

F12 — Mental and behavioural disorders due to use of cannabinoids: facilitator sheet

Teaching objective

For F12, the central classification question is often not about dependence at all but about timing and persistence of psychotic-quality phenomena: did unusual perceptions or beliefs occur only during intoxication and resolve as the drug wore off (intoxication), do they persist as a more sustained psychotic picture temporally linked to use (F12.5), or do they continue well beyond what cannabis alone would explain, raising the question of an independent psychotic illness that cannabis use may have precipitated or coincided with?

Choose material

Worked example · Case: Suspicious at the party, back to normal by morning · Case: Three weeks on, and still not right

Worked example

Show scenario

A 20-year-old university student used cannabis at a party and became convinced that other guests were talking about him and watching him, alongside mild visual distortions. He was noticeably anxious and suspicious for the rest of the evening. By the next morning, after sleeping it off, he reported feeling completely back to normal and could not understand what had come over him. He has no family history of psychotic illness and this was his first time using cannabis.

(or reveal one step at a time below)
  1. Reveal step 1

    Step 1 — Check timing of onset: the suspiciousness and perceptual distortion began during use, which is consistent with an intoxication-related phenomenon rather than an independent process.

  2. Reveal step 2

    Step 2 — Check duration: the symptoms fully resolved by the next morning, well within the expected intoxication window, rather than persisting for days or weeks.

  3. Reveal step 3

    Step 3 — Check for risk factors for an independent illness: no family history and no prior psychotic episodes, weakening the case for an independent psychotic illness.

  4. Reveal step 4

    Step 4 — Weigh against F12.5: because the symptoms did not persist beyond the expected intoxication period, this does not meet the more sustained picture required for a psychotic disorder subtype.

  5. Reveal step 5

    Conclusion — This is best classified as acute intoxication (F12.0) with transient psychotic-quality phenomena, not a substance-induced psychotic disorder, because the symptoms were confined to, and resolved with, the intoxication period.

Comparison points

F12's intoxication state is distinguished from its psychotic-disorder subtype mainly by duration and severity beyond the expected intoxication window, and the psychotic-disorder subtype is distinguished from an independent psychiatric illness by whether symptoms persist well beyond what cannabis use alone would explain.

Discussion prompts

(or reveal one at a time below)
  1. Prompt 1

    Without looking back at the page, state the single most useful question for distinguishing intoxication from a cannabis-induced psychotic disorder.

  2. Prompt 2

    Name one feature that would raise concern about an independent psychotic illness rather than a substance-induced one.

  3. Prompt 3

    Explain in one sentence why regular cannabis use alone does not establish dependence syndrome.

Summary

Perceptual or paranoid phenomena during cannabis use are usually intoxication if they resolve within hours; a more sustained picture, or one persisting well beyond expected timing, raises a substance-induced psychotic disorder or an independent illness.