Low Mood/irritability and Cannabis Withdrawal — Free SCA Practice Case

1. Diagnostic Distinction: Cannabis Withdrawal Syndrome vs Primary Depression

The central diagnostic challenge in this case is distinguishing Cannabis Withdrawal Syndrome (CWS) from a primary depressive or anxiety disorder. This distinction has direct management implications and must be made before any psychiatric diagnosis is formulated.

• ●Cannabis Withdrawal Syndrome (recognised in DSM-5 and ICD-11) occurs following abrupt cessation or significant reduction in heavy, prolonged use. It is not a behavioural quirk — it is a physiologically mediated syndrome.
• ●Chronic THC exposure downregulates CB1 cannabinoid receptors, leading to a hyper-aroused, dopamine-depleted state on cessation. This directly produces the mood and neurovegetative symptoms that mimic depression.
• ●The withdrawal symptom cluster includes: irritability and anger (often the most pronounced feature), insomnia, vivid and disturbing dreams, depressed mood, reduced appetite, nausea, night sweats, tremor, headache, and restlessness. Onset is typically within 24–72 hours of cessation, peaking at days 2–6.
• ●The diagnostic key is temporal correlation: symptoms that emerge or acutely worsen within 48 hours of stopping cannabis are withdrawal, not a primary disorder. Candidates must establish the timeline explicitly.
• ●A reliable diagnosis of a primary mood disorder cannot be made while a patient is actively withdrawing from a substance that directly disrupts mood, sleep, and neurochemistry. Psychiatric assessment should be deferred until a sustained period of abstinence (typically 3–4 weeks) has been achieved.

2. Safe Prescribing in Under-18s: SSRIs and Hypnotics

Two prescribing decisions are tested in this case. Both require a firm, professionally explained refusal.

SSRIs (NICE CG28 / NICE NG134):

• ●GPs must not initiate antidepressants for depression in under-18s in primary care. This is a hard boundary — not a preference.
• ●SSRI initiation in adolescents requires a formal CAMHS assessment and, where prescribed, weekly monitoring for the first four weeks due to the documented risk of paradoxical agitation and emergent suicidal ideation.
• ●The rationale for declining must be explained to the patient clearly and non-punitively: not that the GP doubts their distress, but that the diagnosis cannot be confirmed while withdrawal is active, and that prescribing requires specialist oversight in this age group.
• ●The candidate should commit explicitly to reassessing mood once the withdrawal period has resolved and to referring to CAMHS if depression is confirmed at that point.

Hypnotics and Sedating Agents:

• ●Do not prescribe zopiclone, promethazine, melatonin, or any sedating medication for withdrawal insomnia in a 17-year-old.
• ●There is no evidence base for pharmacological sleep aids in adolescent CWS, and substituting one dependency risk for another is clinically and ethically inappropriate.
• ●Withdrawal insomnia is best managed with structured non-pharmacological sleep hygiene advice (see Section 4).

3. Adolescent Confidentiality and Gillick Competence

This is a video consultation with a 17-year-old disclosing substance use. Confidentiality must be addressed explicitly and early.

• ●At 17, a young person is presumed to have capacity to consent to medical treatment under the Family Law Reform Act 1969. Gillick competence applies to those under 16; at 17, capacity is presumed as for an adult.
• ●The GMC requires that a competent young person's confidentiality be respected to the same standard as an adult's, unless there is a serious and immediate risk of harm to themselves or others.
• ●Routine disclosure about cannabis use and low mood does not meet the threshold for breach of confidentiality. The candidate must make this explicit to Leo — not a vague reassurance, but a clear statement of the rule and its exception: "Everything you tell me today is confidential. The only exception would be if I was seriously concerned for your safety — and even then I would always try to speak to you about it first."

4. Clinical Management: Cannabis Withdrawal

Management has four components: psychoeducation, non-pharmacological symptom support, harm reduction, and referral.

Psychoeducation — Reframing the Patient's Belief:

• ●Leo believes cannabis is his medicine and that his symptoms represent depression. The candidate must correct this belief clearly, accessibly, and without condescension.
• ●The reframe: the brain has become dependent on THC to regulate mood and sleep. Without it, the system is dysregulated. The anger, insomnia, and low mood are not signs of underlying depression — they are signs that the brain is readjusting. The cannabis has been creating the problem it appeared to solve.
• ●After delivering this explanation, check understanding and give Leo space to respond — this is the pivotal moment of the consultation.

Withdrawal Timeline — Setting Expectations:

• ●Symptoms typically peak at days 2–6 and largely resolve within 1–2 weeks of cessation.
• ●Giving Leo a realistic timeline is essential: without it, he will interpret continued symptoms as evidence that he must return to cannabis, making relapse almost inevitable.

Non-Pharmacological Symptom Support:

• ●Regular physical exercise — reduces irritability and promotes natural sleep
• ●Strict sleep hygiene: consistent bedtime, no screens in the hour before sleep, cool room, avoid caffeine after midday
• ●Regular small meals and adequate hydration despite reduced appetite
• ●Acknowledging that the first 5–7 days are the hardest and that this is time-limited

Harm Reduction (If Full Cessation Is Not the Immediate Goal):

• ●If Leo expresses ambivalence about stopping, a harm reduction approach is clinically appropriate and more likely to produce engagement than demanding immediate abstinence.
• ●This includes: reducing frequency, avoiding daytime use, avoiding use before revision sessions, and avoiding mixing cannabis with tobacco.
• ●Motivational Interviewing (OARS: open questions, affirmations, reflective listening, summaries) is the evidence-based framework for exploring ambivalence in adolescent substance use.

5. Referral Pathways: CYP Drug and Alcohol Services vs CAMHS

Two distinct pathways apply to this case, and candidates must understand the distinction.

CYP Drug and Alcohol Services (primary referral):

• ●Adolescents with cannabis dependency are referred first to Local Authority-commissioned Children and Young People's Drug and Alcohol Services — not to CAMHS. These services (often delivered by organisations such as Change Grow Live or We Are With You) provide youth-specific workers, motivational enhancement therapy, CBT for substance use, and harm reduction counselling.
• ●Referring to adult drug and alcohol services is inappropriate for a 17-year-old.

CAMHS (conditional referral):

• ●CAMHS referral becomes appropriate if: (1) Leo meets threshold for psychosis or severe mental illness, (2) there is active suicidality or self-harm risk, or (3) a formal depressive disorder is confirmed after sustained abstinence.
• ●In this consultation, CAMHS referral is not yet indicated — but the candidate should document a clear plan for reassessing mood at 2–4 weeks post-withdrawal and for referring if depression is confirmed at that point.

School and Pastoral Support:

• ●Given Leo's immediate risk to his A-Level results and conditional university offer, the candidate should explore whether school pastoral support, adjusted workload expectations, or a GP letter to the school would be helpful — this is part of holistic management.

6. Cannabis-Associated Psychosis and Red Flags

Heavy adolescent cannabis use carries a specific and significant risk of psychotic illness that must be screened for in this consultation.

• ●Cannabis-associated psychosis: Regular heavy use of high-potency cannabis (skunk/sinsemilla) in adolescence is associated with a substantially elevated risk of psychotic illness, including early-onset schizophrenia. The risk is higher with earlier age of initiation and greater frequency of use.
• ●The candidate must screen explicitly for: paranoia, auditory hallucinations, unusual perceptual experiences, and thought disorganisation.
• ●Leo denies all of these — but the screen must be documented.
• ●Red flags requiring same-day action: any features of acute psychosis; active suicidal ideation with intent or plan; inability to care for self; risk of harm to others.
• ●Red flags requiring urgent (within days) review: emerging or worsening paranoia without full psychotic features; marked functional deterioration not explained by withdrawal; sustained suicidal ideation without immediate plan.

7. Safety Netting and Follow-Up

Safety netting in this case must be specific — not generic reassurance.

• ●Advise Leo to contact the surgery same-day or attend A&E if he develops: paranoia, hearing voices, thoughts of self-harm or suicide, or inability to care for himself.
• ●Advise him to call 999 or go to A&E if he is in immediate danger.
• ●Give Leo a named route back to care — not "come back if you're worried." He should know that his GP is the point of contact and that he can call the same day if needed.
• ●Follow-up appointment: arrange a specific review at 2 weeks to reassess mood formally once the acute withdrawal period has resolved, and to determine whether a CAMHS referral for depression assessment is indicated at that point. Document the rationale for deferring the depression diagnosis explicitly.

8. Common Candidate Mistakes in This Case

• ●Prescribing SSRIs over video to a 17-year-old is the most significant error in this case. It represents a failure of safe prescribing, a failure to identify the withdrawal syndrome, and an inappropriate response to an adolescent presenting with a substance dependency. It is a critical fail.
• ●Missing the cannabis use entirely — by failing to ask about substance use, drugs, or coping mechanisms — means the withdrawal syndrome is never identified and the entire consultation is built on a false premise.
• ●Accepting "a bit of weed" at face value without quantifying frequency, duration, and escalation. 2–3 joints every evening for 6 months represents physiological dependence, not recreational use. The escalation pattern and the abrupt cessation must be established.
• ●Lecturing Leo about cannabis harms without first acknowledging his distress causes him to shut down. The consultation must start with validation of his academic pressure, not a cannabis warning.
• ●Providing no withdrawal timeline — leaving Leo without a framework for what to expect makes relapse highly likely.
• ●Referring to CAMHS immediately without first screening for the clinical features that would determine priority, or without explaining why the depression diagnosis must be deferred.

9. The HEADSS Framework in Adolescent Consultations

This case tests the candidate's ability to use a structured adolescent psychosocial assessment framework rather than a purely biomedical history.

• ●HEADSS (Home, Education/Employment, Activities, Drugs/Alcohol, Suicidality/Self-harm/Sex) is the validated framework for adolescent psychosocial review. It is the adolescent equivalent of a systems review.
• ●Using HEADSS in this case systematically uncovers: the home situation (parental separation, guilt about mum), education pressure (A-Levels, university offer), the cannabis use (only disclosed if directly asked), and the risk screen (self-harm, suicidality).
• ●A purely biomedical approach — symptom review, examination, diagnosis, management — will miss the cannabis disclosure and therefore misdiagnose the case entirely.
• ●Begin with open questions and build rapport before the sensitive domains (drugs, suicidality) — but do not avoid these domains because the patient is a teenager.