Saudi Board Psychiatry Part 1 Complete Review Guide 2026–2027

4. GABA is the main inhibitory brain transmitter (glycine in the spinal cord). Benzodiazepines bind an allosteric GABA-A site and increase chloride channel opening frequency.
5. Serotonin is made from tryptophan via 5-HTP. Dopamine is made from tyrosine, and tyrosine hydroxylase is the rate-limiting enzyme.
6. NMDA receptor hypofunction underlies the glutamate hypothesis of schizophrenia, since ketamine and PCP produce positive and negative symptoms.
7. Depression shows HPA axis hyperactivity, dexamethasone non-suppression and reduced REM latency. PTSD shows low or normal basal cortisol with enhanced negative feedback.
8. Orexin (hypocretin) from the lateral hypothalamus promotes wakefulness. Its loss causes narcolepsy type 1.
9. Alpha rhythm (8-13 Hz) dominates relaxed wakefulness with eyes closed. Sleep spindles and K-complexes mark stage N2, about 50% of sleep.
10. A variable ratio schedule produces behaviour most resistant to extinction, as in gambling.
11. Piaget: sensorimotor, preoperational, concrete operational (7-11 years, when conservation appears), then formal operational.
12. Erikson's adolescent stage is identity vs role confusion. Mahler's rapprochement is at about 16-24 months. Stranger anxiety appears at about 7-9 months.
13. Disorganised attachment is linked to frightening or abusive caregiving. An avoidant infant ignores the caregiver on reunion.
14. Mature defences (Vaillant): humour, altruism, sublimation and suppression. Projection is immature. Undoing, isolation of affect and reaction formation are typical of OCD.
15. Authors: Kohut (self psychology), Winnicott (good-enough mother, transitional object), Seligman (learned helplessness), Festinger (cognitive dissonance), Engel (biopsychosocial model), Parsons (sick role).
16. High expressed emotion in the family (critical comments, hostility, emotional over-involvement) increases relapse in schizophrenia.
17. Lifetime schizophrenia risk is about 0.3-0.7% in the population and about 40-50% in a monozygotic co-twin. Bipolar I heritability is about 60-85%.
18. 22q11.2 deletion carries about 25% psychosis risk. APOE ε4 is the strongest genetic risk for late-onset Alzheimer disease. Huntington disease is autosomal dominant CAG expansion with anticipation.
19. Down syndrome is the most common chromosomal cause of intellectual disability. Fragile X (CGG expansion in FMR1) is the most common inherited cause.
20. Case-control studies suit rare outcomes and report odds ratios. Cross-sectional studies measure prevalence and cannot show temporality.
21. A type I error rejects a true null hypothesis (false positive, α). NNT = 1 / absolute risk reduction, so an ARR of 0.2 gives NNT 5.
22. Cohen's kappa measures inter-rater agreement corrected for chance. Validity means measuring what is intended. Reliability means consistency.
23. DSM-5-TR added prolonged grief disorder (at least 12 months after the loss in adults). ICD-11 added complex PTSD and grades personality disorder by severity.
24. M'Naghten: not knowing the nature or wrongfulness of the act. Fitness to stand trial: understanding proceedings and assisting counsel (Dusky). Testamentary capacity: knowing the will, the property and the heirs (Banks v Goodfellow).

Common mistakes in this chapter

• ✕ Negative reinforcement is often confused with punishment. Negative reinforcement increases a behaviour by removing an aversive stimulus. Punishment decreases a behaviour.
• ✕ Serotonin is wrongly placed in the locus coeruleus. The locus coeruleus makes noradrenaline. Serotonin comes from the raphe nuclei.
• ✕ High sensitivity is thought to confirm disease. A highly sensitive test rules disease out when negative (SnNout). A highly specific test rules it in when positive (SpPin).
• ✕ PPV is assumed to be fixed. It rises as prevalence rises, even when sensitivity and specificity stay the same.
• ✕ Agreeing with the doctor is treated as part of capacity. A patient with capacity may refuse treatment, even if the choice seems unwise.
• ✕ Malingering is confused with factitious disorder. Malingering is driven by an external incentive. Factitious disorder is driven by the wish for the sick role.
• ✕ Schizophrenia is assumed to be the main driver of community violence. Substance use disorders carry the strongest association, and past violence is the best single predictor.
• ✕ The expert witness is taken to be the patient's advocate. The primary duty is to the court, with objectivity.