Psychologists weigh three D's: deviance (the behavior departs markedly from cultural norms), distress (the person suffers), and dysfunction (everyday functioning is impaired). No single D is sufficient — an unusual but harmless hobby is not a disorder — and every judgment is made against cultural context. A working modern definition: maladaptive behavior that causes distress or impairs functioning.
Two causal frames organize the field. The medical model treats psychological disorders like physical illnesses, with diagnosable symptoms and treatments — historically humane, but biased toward purely biological explanation. The diathesis-stress model is broader: a disorder emerges when an underlying predisposition (genetic, biological, or psychological — the diathesis) interacts with a triggering stressor. It explains why one identical twin can develop schizophrenia while the other never does.
Diagnosis itself is standardized by the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th edition) — the classification system that gives clinicians shared criteria and terminology. Labels help communication but carry a cost: once attached, a label can become a lens that makes ordinary behavior look symptomatic.
All share excessive fear or anxiety out of proportion to the actual threat, plus impairment:
Two conditions involve anxiety but sit in their own DSM-5 categories — a favorite exam distinction:
Major depressive disorder (MDD) requires at least two weeks of depressed mood or anhedonia (loss of interest or pleasure) nearly every day, with symptoms such as sleep and appetite changes, fatigue, worthlessness, poor concentration, and sometimes thoughts of death. Persistent depressive disorder is the lower-grade, longer-haul form: depressed mood more days than not for at least two years.
Depression alone is unipolar. Bipolar disorders add mania: a distinct period (a week or more) of abnormally elevated or irritable mood with decreased need for sleep, grandiosity, racing thoughts and pressured speech, distractibility, and impulsive, risky behavior. Bipolar I requires at least one full manic episode; bipolar II pairs major depressive episodes with milder hypomania. Scan every "depression" scenario for a past high-energy episode — if one appears, the diagnosis flips to bipolar.
Biologically, depression is linked to reduced serotonin and norepinephrine activity; cognitively, to Beck's negative views of self, world, and future, plus learned helplessness and rumination.
Schizophrenia is a psychotic disorder — a break with reality disturbing thought, perception, emotion, and behavior. Its symptoms split into two families:
| Type | Meaning | Examples |
|---|---|---|
| Positive symptoms | Additions to normal experience | Delusions (false beliefs, e.g., persecution), hallucinations (false perceptions, most often auditory voices), disorganized speech |
| Negative symptoms | Subtractions from normal functioning | Flat affect (reduced emotional expression), avolition (loss of goal-directed motivation), social withdrawal |
"Positive" means added, not good. The dopamine hypothesis links positive symptoms to overactive dopamine systems: drugs that block dopamine receptors reduce delusions and hallucinations, while drugs that boost dopamine can induce psychotic symptoms. Onset is typically late adolescence to early adulthood, often after a stressor — a textbook diathesis-stress pattern. And schizophrenia is not "split personality"; the split is from reality.
Dissociative disorders disrupt consciousness, memory, or identity. Dissociative amnesia is an inability to recall important personal information — usually following trauma — far beyond ordinary forgetting, with identity otherwise intact. Dissociative identity disorder (DID) involves two or more distinct identity states with memory gaps between them; it remains controversial, with skeptics arguing some diagnoses reflect therapist suggestion or media influence.
Somatic symptom disorder involves real, distressing physical symptoms accompanied by excessive thoughts and anxiety about them. It is not faking — the distress is genuine but disproportionate.
Personality disorders are enduring, inflexible patterns of experience and behavior that deviate from cultural expectations and impair functioning. Two Cluster B exemplars dominate the exam:
These begin in childhood. Autism spectrum disorder (ASD) involves persistent deficits in social communication and interaction plus restricted, repetitive behaviors and interests, on a spectrum of severity. Attention-deficit/hyperactivity disorder (ADHD) is a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning — a neurodevelopmental condition, not a failure of willpower.
A stressor is the triggering event; stress is the process of appraising and responding to it. Hans Selye found that the body answers any prolonged stressor with the same three-stage pattern, the general adaptation syndrome (GAS):
[GRAPH: resistance-to-stress plotted over time — a brief dip at the alarm stage, a long elevated plateau during resistance, then a steep decline into exhaustion.]
Chronic stress and sustained cortisol suppress the immune system, which is why illness clusters at the end of long stressful stretches. Coping comes in two flavors: problem-focused coping acts on the stressor itself (get a tutor, renegotiate a deadline) and fits controllable situations; emotion-focused coping manages your reaction (seek comfort, reframe, lean on others) and fits stressors you cannot change. Perceived control and social support both reliably buffer stress and predict better health outcomes.
1. (E) Specific phobia. An intense, irrational fear of one particular situation (flying), with avoidance and insight that the fear is excessive, is the definition. (A) GAD is free-floating worry across many topics, not one focused fear; (B) panic disorder centers on recurrent unexpected attacks and dread of the next one — Nadia's fear is cued and specific; (C) OCD requires obsessions relieved by compulsive rituals, absent here; (D) agoraphobia is fear of situations where escape is difficult in general (crowds, transit), not one specific feared object. Fix: One named object/situation + avoidance = specific phobia; worry about everything = GAD.
2. (C) Alarm → resistance → exhaustion. The initial fight-or-flight surge (alarm) gives way to sustained coping at elevated cortisol (resistance), and if the stressor persists, reserves deplete (exhaustion). (A), (B), (D), and (E) scramble the sequence — the common error is placing exhaustion before resistance, forgetting that resistance means you are still holding the line at a cost. Fix: GAS = A-R-E: sound the Alarm, put up Resistance, reach Exhaustion.
3. (D) Bipolar I disorder. A week of decreased need for sleep, grandiosity, pressured speech, and impulsive spending is a full manic episode, and one manic episode makes the diagnosis bipolar I. (A) MDD is the opposite mood pole with no mania permitted; (B) GAD involves worry, not euphoric energy; (C) persistent depressive disorder is two-plus years of low-grade depression; (E) schizophrenia requires psychotic symptoms such as delusions or hallucinations, not described here. Fix: Any full manic episode (no sleep + grandiosity + racing speech + recklessness) = bipolar I, whatever the depressive history.
4. (B) Negative symptoms. Flat affect and avolition are subtractions — normal functions diminished or missing. (A) positive symptoms are additions like hallucinations and delusions — "positive" means added, not good; (C) manic symptoms are elevated mood and energy, the reverse of this presentation; (D) dissociative symptoms involve disrupted memory or identity; (E) compulsions are OCD's anxiety-reducing rituals. Fix: Present-but-shouldn't-be = positive (+ added); missing-but-should-be-there = negative (− subtracted).
5. (D) Obsessive-compulsive disorder. Intrusive thoughts (obsessions) driving repetitive washing that briefly relieves anxiety (compulsions) is OCD's defining loop — classified in its own DSM-5 category, apart from the anxiety disorders. (A) a phobia involves fear and avoidance of an object, not ritual relief of intrusive thoughts; (B) GAD lacks rituals; (C) panic disorder centers on sudden attacks; (E) somatic symptom disorder involves distressing physical symptoms with excessive health worry, not contamination rituals. Fix: Intrusive thought + ritual that relieves it = OCD (its own DSM-5 category).
6. (C) An underlying predisposition interacting with a triggering stressor. That interaction — diathesis × stress — is the model's literal content, and it explains why identical twins are not 100% concordant for disorders. (A) and (B) each name only one factor, which is exactly what the model rejects; (D) describes labeling theory, a different concern; (E) is the dopamine hypothesis, one biological mechanism for one disorder, not the general model. Fix: Diathesis-stress = loaded gun (predisposition) + pulled trigger (stressor); neither alone is enough.
7. (A) Posttraumatic stress disorder. Nightmares, flashbacks, and hypervigilance following a traumatic event are PTSD's core — and the DSM-5 files it under trauma- and stressor-related disorders because the traumatic trigger is required. (B) panic attacks are sudden and unexpected, not tied to trauma reminders; (C) GAD is diffuse worry without a defining trauma; (D) a specific phobia is focused fear without re-experiencing symptoms like flashbacks; (E) dissociative amnesia involves memory loss, whereas Priya relives the event vividly. Fix: Trauma + re-experiencing (flashbacks/nightmares) + hypervigilance = PTSD.
8. (A) Antisocial personality disorder. A persistent pattern of violating others' rights — deceit, exploitation, lawbreaking — with no remorse is the defining profile. (B) borderline centers on unstable relationships, self-image, and fear of abandonment, not remorseless exploitation; (C) avoidant personality disorder involves social inhibition and fear of criticism; (D) DID involves multiple identity states, not a moral-conduct pattern; (E) paranoid personality disorder is pervasive distrust, not exploitation without guilt. Fix: Violates others' rights + lacks remorse = antisocial; instability + abandonment fear = borderline.
9. (D) Dissociative amnesia. Trauma-linked loss of important personal memories, far beyond normal forgetting, with a single intact identity is the definition. (A) DID requires two or more distinct identity states — Elena has one; (B) schizophrenia involves psychosis, not isolated memory gaps; (C) somatic symptom disorder centers on physical complaints; (E) bipolar II is a mood disorder with hypomania and depression. Fix: Memory gap only = dissociative amnesia; multiple identities with gaps between them = DID.
10. (E) A break with reality marked by delusions and hallucinations. Schizophrenia's "split" is from reality — psychosis — not into multiple personalities. (A) describes dissociative identity disorder, the exact condition the myth confuses it with; (B) describes bipolar disorder; (C) describes agoraphobia; (D) describes somatic symptom disorder. Fix: Schizophrenia = split from REALITY (psychosis); "split personality" = DID, a dissociative disorder.
11. (B) Emotion-focused coping. When a stressor cannot be changed, managing your emotional response — seeking support, reframing, grieving — is the adaptive match. (A) problem-focused coping targets the stressor itself, which is futile against an incurable illness; (C) learned helplessness is a maladaptive collapse of effort, not a coping strategy; (D) rumination is repetitive brooding that worsens distress; (E) repression is an unconscious defense, not a deliberate strategy. Fix: Controllable stressor → problem-focused; uncontrollable stressor → emotion-focused. Match coping to control.
12. (E) Major depressive disorder. Two-plus weeks (here a month) of near-daily depressed mood, anhedonia, sleep disturbance, and worthlessness — with no manic or hypomanic history — meets MDD. (A) bipolar I requires a manic episode, explicitly ruled out; (B) persistent depressive disorder requires the low mood to run at least two years; (C) GAD's core is uncontrollable worry, not sadness and anhedonia; (D) somatic symptom disorder centers on physical symptoms and health anxiety. Fix: Two-plus weeks of depression + no mania ever = MDD; the same picture stretched over two-plus years = persistent depressive disorder.
1. (E) Specific phobia. An intense, irrational fear of one particular situation (flying), with avoidance and insight that the fear is excessive, is the definition. (A) GAD is free-floating worry across many topics, not one focused fear; (B) panic disorder centers on recurrent unexpected attacks and dread of the next one — Nadia's fear is cued and specific; (C) OCD requires obsessions relieved by compulsive rituals, absent here; (D) agoraphobia is fear of situations where escape is difficult in general (crowds, transit), not one specific feared object. Fix: One named object/situation + avoidance = specific phobia; worry about everything = GAD.
2. (C) Alarm → resistance → exhaustion. The initial fight-or-flight surge (alarm) gives way to sustained coping at elevated cortisol (resistance), and if the stressor persists, reserves deplete (exhaustion). (A), (B), (D), and (E) scramble the sequence — the common error is placing exhaustion before resistance, forgetting that resistance means you are still holding the line at a cost. Fix: GAS = A-R-E: sound the Alarm, put up Resistance, reach Exhaustion.
3. (D) Bipolar I disorder. A week of decreased need for sleep, grandiosity, pressured speech, and impulsive spending is a full manic episode, and one manic episode makes the diagnosis bipolar I. (A) MDD is the opposite mood pole with no mania permitted; (B) GAD involves worry, not euphoric energy; (C) persistent depressive disorder is two-plus years of low-grade depression; (E) schizophrenia requires psychotic symptoms such as delusions or hallucinations, not described here. Fix: Any full manic episode (no sleep + grandiosity + racing speech + recklessness) = bipolar I, whatever the depressive history.
4. (B) Negative symptoms. Flat affect and avolition are subtractions — normal functions diminished or missing. (A) positive symptoms are additions like hallucinations and delusions — "positive" means added, not good; (C) manic symptoms are elevated mood and energy, the reverse of this presentation; (D) dissociative symptoms involve disrupted memory or identity; (E) compulsions are OCD's anxiety-reducing rituals. Fix: Present-but-shouldn't-be = positive (+ added); missing-but-should-be-there = negative (− subtracted).
5. (D) Obsessive-compulsive disorder. Intrusive thoughts (obsessions) driving repetitive washing that briefly relieves anxiety (compulsions) is OCD's defining loop — classified in its own DSM-5 category, apart from the anxiety disorders. (A) a phobia involves fear and avoidance of an object, not ritual relief of intrusive thoughts; (B) GAD lacks rituals; (C) panic disorder centers on sudden attacks; (E) somatic symptom disorder involves distressing physical symptoms with excessive health worry, not contamination rituals. Fix: Intrusive thought + ritual that relieves it = OCD (its own DSM-5 category).
6. (C) An underlying predisposition interacting with a triggering stressor. That interaction — diathesis × stress — is the model's literal content, and it explains why identical twins are not 100% concordant for disorders. (A) and (B) each name only one factor, which is exactly what the model rejects; (D) describes labeling theory, a different concern; (E) is the dopamine hypothesis, one biological mechanism for one disorder, not the general model. Fix: Diathesis-stress = loaded gun (predisposition) + pulled trigger (stressor); neither alone is enough.
7. (A) Posttraumatic stress disorder. Nightmares, flashbacks, and hypervigilance following a traumatic event are PTSD's core — and the DSM-5 files it under trauma- and stressor-related disorders because the traumatic trigger is required. (B) panic attacks are sudden and unexpected, not tied to trauma reminders; (C) GAD is diffuse worry without a defining trauma; (D) a specific phobia is focused fear without re-experiencing symptoms like flashbacks; (E) dissociative amnesia involves memory loss, whereas Priya relives the event vividly. Fix: Trauma + re-experiencing (flashbacks/nightmares) + hypervigilance = PTSD.
8. (A) Antisocial personality disorder. A persistent pattern of violating others' rights — deceit, exploitation, lawbreaking — with no remorse is the defining profile. (B) borderline centers on unstable relationships, self-image, and fear of abandonment, not remorseless exploitation; (C) avoidant personality disorder involves social inhibition and fear of criticism; (D) DID involves multiple identity states, not a moral-conduct pattern; (E) paranoid personality disorder is pervasive distrust, not exploitation without guilt. Fix: Violates others' rights + lacks remorse = antisocial; instability + abandonment fear = borderline.
9. (D) Dissociative amnesia. Trauma-linked loss of important personal memories, far beyond normal forgetting, with a single intact identity is the definition. (A) DID requires two or more distinct identity states — Elena has one; (B) schizophrenia involves psychosis, not isolated memory gaps; (C) somatic symptom disorder centers on physical complaints; (E) bipolar II is a mood disorder with hypomania and depression. Fix: Memory gap only = dissociative amnesia; multiple identities with gaps between them = DID.
10. (E) A break with reality marked by delusions and hallucinations. Schizophrenia's "split" is from reality — psychosis — not into multiple personalities. (A) describes dissociative identity disorder, the exact condition the myth confuses it with; (B) describes bipolar disorder; (C) describes agoraphobia; (D) describes somatic symptom disorder. Fix: Schizophrenia = split from REALITY (psychosis); "split personality" = DID, a dissociative disorder.
11. (B) Emotion-focused coping. When a stressor cannot be changed, managing your emotional response — seeking support, reframing, grieving — is the adaptive match. (A) problem-focused coping targets the stressor itself, which is futile against an incurable illness; (C) learned helplessness is a maladaptive collapse of effort, not a coping strategy; (D) rumination is repetitive brooding that worsens distress; (E) repression is an unconscious defense, not a deliberate strategy. Fix: Controllable stressor → problem-focused; uncontrollable stressor → emotion-focused. Match coping to control.
12. (E) Major depressive disorder. Two-plus weeks (here a month) of near-daily depressed mood, anhedonia, sleep disturbance, and worthlessness — with no manic or hypomanic history — meets MDD. (A) bipolar I requires a manic episode, explicitly ruled out; (B) persistent depressive disorder requires the low mood to run at least two years; (C) GAD's core is uncontrollable worry, not sadness and anhedonia; (D) somatic symptom disorder centers on physical symptoms and health anxiety. Fix: Two-plus weeks of depression + no mania ever = MDD; the same picture stretched over two-plus years = persistent depressive disorder.