Why This Matters
Psychological disorders represent one of the most heavily tested areas on the AP Psychology exam because they integrate concepts from across the entire course—biological bases of behavior, learning principles, cognitive processes, and social influences. You're being tested on your ability to distinguish between disorders that may look similar on the surface but differ in their underlying mechanisms, symptom patterns, and diagnostic criteria. The exam loves to ask you to differentiate anxiety disorders from mood disorders, or to identify which disorder best matches a case study vignette.
Understanding these disorders isn't just about memorizing symptom lists—it's about grasping the biopsychosocial model that explains how genetic vulnerabilities, neurochemical imbalances, learned behaviors, and environmental stressors interact to produce psychological dysfunction. When you encounter an FRQ asking about treatment approaches or a multiple-choice question about etiology, you need to connect each disorder to its conceptual category. Don't just memorize that schizophrenia involves hallucinations—know why it's classified as a psychotic disorder and how that differs from the cognitive distortions seen in depression.
Mood Disorders: When Emotional Regulation Breaks Down
Mood disorders involve persistent disturbances in emotional state that go far beyond normal fluctuations in feeling. These conditions reflect dysregulation in neurotransmitter systems—particularly serotonin, norepinephrine, and dopamine—combined with cognitive patterns that maintain negative emotional states.
Major Depressive Disorder
- Persistent depressed mood and anhedonia—the loss of interest or pleasure in previously enjoyed activities is often the most telling diagnostic feature
- Neurobiological basis involves reduced activity in the prefrontal cortex and dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, linking it to chronic stress responses
- Cognitive symptoms like difficulty concentrating and feelings of worthlessness reflect Aaron Beck's cognitive triad—negative views of self, world, and future
Bipolar Disorder
- Alternating episodes of depression and mania distinguish this from unipolar depression—manic phases include elevated mood, decreased need for sleep, and grandiosity
- Impulsive and risky behavior during mania can include excessive spending, sexual indiscretions, or reckless decisions with lasting consequences
- Biological component is strong, with high heritability estimates and effectiveness of mood stabilizers like lithium suggesting neurochemical origins
Compare: Major Depressive Disorder vs. Bipolar Disorder—both involve depressive episodes with similar symptoms, but bipolar includes manic or hypomanic phases. If an FRQ presents a case with "periods of unusually high energy and little need for sleep," think bipolar, not MDD.
Anxiety Disorders: The Fear Response Gone Awry
Anxiety disorders share a common thread of excessive fear and anxiety that is disproportionate to actual threat. The amygdala—the brain's fear center—shows hyperactivity in these conditions, while the prefrontal cortex fails to adequately regulate the fear response.
Generalized Anxiety Disorder
- Excessive, uncontrollable worry about multiple life domains (work, health, family) lasting at least six months defines this condition
- Physical symptoms include muscle tension, restlessness, and sleep disturbances—the body stays in a chronic state of sympathetic nervous system activation
- Free-floating anxiety distinguishes GAD from other anxiety disorders—the worry isn't tied to a specific trigger or situation
Panic Disorder
- Recurrent, unexpected panic attacks with intense physical symptoms like racing heart, shortness of breath, and feelings of impending doom
- Fear of future attacks leads to anticipatory anxiety and often agoraphobia—avoidance of situations where escape might be difficult
- Misinterpretation of bodily sensations plays a key role; cognitive-behavioral models emphasize how catastrophic thinking about physical symptoms maintains the disorder
Social Anxiety Disorder
- Intense fear of negative evaluation in social or performance situations goes beyond normal shyness or stage fright
- Avoidance behavior can severely limit career advancement, relationships, and daily functioning
- Cognitive distortions include overestimating the likelihood of embarrassment and underestimating one's ability to cope with social situations
Specific Phobias
- Intense, irrational fear of a specific object or situation (heights, spiders, flying) that is out of proportion to actual danger
- Classical conditioning often explains acquisition—a neutral stimulus becomes associated with a fear response through direct experience or observational learning
- Exposure therapy is highly effective, using principles of extinction to gradually reduce the conditioned fear response
Compare: GAD vs. Panic Disorder—GAD involves chronic, diffuse worry across many domains, while panic disorder features discrete, intense episodes of terror. GAD is like a constant low-grade alarm; panic disorder is like sudden false fire alarms.
These disorders involve intrusive thoughts or memories that drive repetitive behaviors or avoidance. While once grouped with anxiety disorders, they're now recognized as distinct categories with unique neurobiological profiles—OCD involves dysfunction in the orbitofrontal cortex and basal ganglia circuits.
Obsessive-Compulsive Disorder (OCD)
- Obsessions are intrusive, unwanted thoughts (contamination fears, doubts about harm) that cause significant distress—not simply excessive worrying
- Compulsions are ritualistic behaviors (washing, checking, counting) performed to neutralize anxiety, but relief is only temporary
- Ego-dystonic nature means individuals recognize their thoughts and behaviors as irrational, distinguishing OCD from delusional disorders
Post-Traumatic Stress Disorder (PTSD)
- Develops after exposure to actual or threatened death, serious injury, or sexual violence—not all stressful events qualify as traumatic
- Four symptom clusters: intrusion (flashbacks, nightmares), avoidance, negative alterations in cognition/mood, and hyperarousal
- Memory consolidation disruption explains why traumatic memories feel vivid and present—the hippocampus fails to properly contextualize the memory as past
Compare: OCD vs. PTSD—both involve intrusive thoughts and avoidance, but OCD obsessions are typically irrational fears unrelated to real events, while PTSD intrusions are memories of actual trauma. Treatment approaches differ accordingly.
Psychotic Disorders: Breaks from Reality
Psychotic disorders involve fundamental disturbances in perception and thought that disconnect individuals from shared reality. Dopamine hypothesis suggests that overactivity in mesolimbic dopamine pathways contributes to positive symptoms, while prefrontal dopamine deficits may underlie negative symptoms.
Schizophrenia
- Positive symptoms include hallucinations (most commonly auditory), delusions (often paranoid or grandiose), and disorganized speech reflecting fragmented thinking
- Negative symptoms involve deficits—flat affect, avolition (lack of motivation), alogia (poverty of speech)—and are often more disabling long-term
- Diathesis-stress model explains onset: genetic vulnerability (high heritability) interacts with environmental stressors like prenatal complications or urban upbringing
Compare: Schizophrenia vs. Dissociative Identity Disorder—despite common misconceptions, these are entirely different conditions. Schizophrenia involves psychotic symptoms and cognitive disorganization; DID involves distinct identity states, typically following severe childhood trauma. The "split" in schizophrenia refers to split from reality, not split personalities.
Personality Disorders: Enduring Patterns of Dysfunction
Personality disorders represent inflexible, maladaptive patterns of thinking, feeling, and behaving that deviate from cultural expectations and cause significant distress. These patterns are ego-syntonic—individuals often don't recognize them as problematic—and typically emerge in adolescence or early adulthood.
Borderline Personality Disorder
- Emotional instability and intense, unstable relationships characterized by alternating between idealization and devaluation of others
- Identity disturbance includes chronic feelings of emptiness and unstable self-image
- Impulsive, self-damaging behaviors and recurrent suicidal threats or self-harm; often associated with history of childhood trauma or invalidating environments
Dissociative Identity Disorder
- Two or more distinct personality states that recurrently take control of behavior, with amnesia between states
- Strongly associated with severe, repeated childhood trauma—dissociation serves as a defense mechanism against overwhelming experiences
- Controversial diagnosis with ongoing debate about prevalence and whether it can be iatrogenically created through suggestive therapy techniques
Compare: Borderline Personality Disorder vs. Bipolar Disorder—both involve mood instability, but BPD mood shifts are rapid (hours) and triggered by interpersonal events, while bipolar episodes last days to weeks and aren't necessarily triggered. BPD also features identity disturbance and fear of abandonment not seen in bipolar.
Neurodevelopmental Disorders: Early-Onset Conditions
Neurodevelopmental disorders emerge during the developmental period and involve deficits that affect personal, social, or academic functioning. Brain development differences—whether genetic, prenatal, or early environmental—create these conditions before or shortly after birth.
Attention-Deficit/Hyperactivity Disorder (ADHD)
- Three presentations: predominantly inattentive, predominantly hyperactive-impulsive, or combined—symptoms must appear before age 12
- Executive function deficits in the prefrontal cortex explain difficulties with organization, working memory, and impulse control
- Stimulant medications (methylphenidate, amphetamines) paradoxically calm symptoms by increasing dopamine and norepinephrine in underactive prefrontal regions
Autism Spectrum Disorder
- Deficits in social communication and interaction include difficulty with nonverbal cues, developing relationships, and understanding others' perspectives (theory of mind)
- Restricted, repetitive behaviors may include stereotyped movements, insistence on sameness, or intensely focused interests
- Spectrum nature means severity varies widely—from individuals requiring substantial support to those with average or above-average intelligence and subtle social difficulties
Compare: ADHD vs. Autism Spectrum Disorder—both are neurodevelopmental and can involve attention difficulties, but ASD is defined by social communication deficits and restricted interests, while ADHD centers on attention regulation and hyperactivity/impulsivity. They can co-occur.
Eating Disorders: When Body Image Distorts Behavior
Eating disorders involve severe disturbances in eating behavior and related thoughts and emotions. Cultural pressures around thinness interact with psychological factors like perfectionism and low self-esteem, and biological vulnerabilities including genetic predisposition.
Anorexia Nervosa
- Restriction of energy intake leading to significantly low body weight, combined with intense fear of gaining weight
- Distorted body image—individuals perceive themselves as overweight despite being underweight, a cognitive distortion central to the disorder
- Highest mortality rate of any psychological disorder due to medical complications (cardiac arrest, organ failure) and suicide risk
Bulimia Nervosa
- Binge-purge cycles: episodes of consuming large amounts of food followed by compensatory behaviors (vomiting, laxatives, excessive exercise)
- Weight often normal or above, making it less visible than anorexia—individuals may hide behaviors due to shame
- Sense of loss of control during binges distinguishes pathological binging from simple overeating
Compare: Anorexia Nervosa vs. Bulimia Nervosa—both involve fear of weight gain and body image disturbance, but anorexia is characterized by restriction and low weight, while bulimia involves binge-purge cycles with often-normal weight. Some individuals transition between diagnoses over time.
Substance use disorders involve patterns of use that cause significant impairment or distress despite negative consequences. Addictive substances hijack the brain's reward circuitry—particularly the mesolimbic dopamine pathway—creating powerful reinforcement that overrides rational decision-making.
Substance Use Disorders
- Tolerance and withdrawal reflect physiological dependence—the brain adapts to the substance's presence, requiring more to achieve effects and producing symptoms when use stops
- Continued use despite consequences (relationship problems, health issues, legal troubles) indicates loss of voluntary control over use
- Psychological and social factors interact with biology—operant conditioning (negative reinforcement of withdrawal relief), classical conditioning (cue-triggered cravings), and social learning all maintain addiction
Quick Reference Table
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| Mood Dysregulation | Major Depressive Disorder, Bipolar Disorder |
| Anxiety/Fear Response | GAD, Panic Disorder, Social Anxiety, Specific Phobias |
| Intrusive Thoughts/Trauma | OCD, PTSD |
| Psychosis/Reality Distortion | Schizophrenia |
| Personality Dysfunction | Borderline Personality Disorder, Dissociative Identity Disorder |
| Neurodevelopmental | ADHD, Autism Spectrum Disorder |
| Body Image/Eating | Anorexia Nervosa, Bulimia Nervosa |
| Reward System Hijacking | Substance Use Disorders |
Self-Check Questions
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Which two anxiety disorders both involve avoidance behavior but differ in whether the trigger is specific or diffuse? What distinguishes their treatment approaches?
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A patient experiences intrusive thoughts about contamination and spends hours washing their hands. Another patient has intrusive memories of a car accident and avoids driving. What disorders do these represent, and what key feature distinguishes them?
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Compare and contrast the positive and negative symptoms of schizophrenia. Which category tends to respond better to antipsychotic medication, and why might this be?
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An FRQ asks you to explain why someone with bipolar disorder might be misdiagnosed with major depressive disorder. What would you include in your response?
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Both anorexia nervosa and bulimia nervosa involve body image disturbance. If given a case study of someone with normal weight who reports episodes of eating large amounts of food followed by excessive exercise, which diagnosis fits better and why?