DHA Mental Health & Psychiatry Flashcards

A 34-year-old woman with bipolar I disorder is stabilized on lithium and becomes pregnant. Her serum lithium level is 0.8 mEq/L. What is the most evidence-based management approach for the third trimester?

Answer: Increase lithium dose to maintain therapeutic levels as GFR rises, then reduce rapidly before delivery to prevent neonatal toxicity

During pregnancy, GFR increases significantly, causing lithium clearance to rise and serum levels to fall — requiring dose increases to maintain efficacy. However, at delivery, GFR normalizes abruptly, causing lithium levels to surge. The correct approach is to increase the dose to compensate for rising clearance during pregnancy and then reduce it sharply just before delivery (or immediately postpartum) to avoid neonatal lithium toxicity (hypotonia, cyanosis, bradycardia). Valproate is more teratogenic than lithium and is not a safer alternative. Monthly monitoring alone is insufficient during rapid physiological changes.

A patient on clozapine develops a sudden fever of 39.2°C, sore throat, and malaise on day 18 of treatment. WBC is 2,800/mm³ with ANC of 900/mm³. What is the correct immediate action?

Answer: Stop clozapine immediately, admit the patient, and do not rechallenge with clozapine

An ANC below 1,000/mm³ meets the threshold for severe neutropenia/agranulocytosis — a life-threatening emergency associated with clozapine. The mandatory response is immediate discontinuation of clozapine, hospital admission, and initiation of reverse isolation. Crucially, once agranulocytosis has occurred, clozapine is absolutely contraindicated for life — rechallenge is never appropriate. G-CSF may be used adjunctively but does not justify continuing the drug. Dose reduction is inadequate and dangerous. Switching to olanzapine without urgent haematological management misses the severity of the presentation.

Which of the following best describes the mechanism by which carbamazepine reduces the plasma levels of haloperidol when co-administered?

Answer: Carbamazepine induces CYP3A4 and CYP2D6, accelerating hepatic metabolism of haloperidol

Carbamazepine is a potent inducer of several cytochrome P450 enzymes, particularly CYP3A4 and CYP2D6 — the primary enzymes responsible for haloperidol's hepatic metabolism. Enzyme induction increases the rate of haloperidol breakdown, significantly reducing its plasma concentration (often by 50–60%), which can lead to loss of antipsychotic efficacy. This is a clinically important pharmacokinetic interaction requiring dose adjustment if the combination is used. Protein displacement and reduced absorption are not the relevant mechanisms here.

A 27-year-old man presents with 18 months of social withdrawal, flat affect, and disorganized speech with no psychotic features or mood episode. He is functionally impaired and has no medical cause identified. He does not meet criteria for schizophrenia. Which diagnosis is most appropriate?

Answer: Schizophrenia

DSM-5 criteria for schizophrenia require two or more characteristic symptoms (delusions, hallucinations, disorganized speech, disorganized/catatonic behaviour, or negative symptoms), with at least one being from the first three — present for at least 1 month — plus continuous signs of disturbance for at least 6 months including prodrome/residual periods, and significant functional decline. Negative symptoms (flat affect, alogia) and disorganized speech alone fulfil the symptom criterion. The 18-month duration with functional impairment satisfies the 6-month threshold. Schizophreniform disorder requires duration of 1–6 months. Schizotypal PD is an Axis II condition and typically less impairing. 'Prodromal phase' is not a DSM-5 formal diagnosis.

A 45-year-old man with treatment-resistant major depressive disorder undergoes electroconvulsive therapy (ECT). After the sixth session he develops persistent anterograde and retrograde amnesia. Which modification to the ECT protocol is most likely to reduce cognitive side effects while preserving efficacy?

Answer: Switch from brief-pulse to ultra-brief pulse width stimulation with right unilateral electrode placement

Cognitive side effects of ECT — particularly amnesia — are most strongly associated with bilateral electrode placement and conventional (brief-pulse) waveform parameters. The evidence-based strategy to minimize cognitive adverse effects without sacrificing antidepressant response is to use right unilateral (RUL) electrode placement combined with ultra-brief pulse width (≤0.3 ms). This combination has been shown in RCTs to produce substantially fewer memory deficits while retaining comparable efficacy at suprathreshold doses. Bilateral placement increases efficacy but worsens cognition. Adding benzodiazepines suppresses seizure duration and can reduce efficacy. Reducing frequency to once weekly significantly prolongs the course without addressing the electrode/waveform drivers of amnesia.

A forensic psychiatry evaluation is requested for a 38-year-old man charged with assault. He claims he was in a dissociative state at the time and has no memory of the event. In the legal context of the DHA/UAE framework and general forensic psychiatry principles, which standard is used to evaluate criminal responsibility (analogous to the 'insanity defence') and what must be demonstrated?

Answer: The M'Naghten standard: the defendant did not know the nature of the act, or did not know it was wrong, due to a disease of the mind

The M'Naghten standard (1843) remains the foundational legal test for insanity used in many jurisdictions influenced by English common law, including GCC-based forensic frameworks that draw on it. It requires that, at the time of the act, the defendant was suffering from a disease of the mind such that they either (1) did not know the nature and quality of the act, or (2) did not know that what they were doing was wrong. Dissociation alone does not automatically satisfy this standard — the clinician must demonstrate a formal mental disease causing the specific cognitive impairment described. The Durham Rule is rarely used. The MPC and Irresistible Impulse tests are used in some US jurisdictions but are not the primary standard in DHA/UAE forensic contexts.