Difficulty: Intermediate | Prerequisites: Personality theories, basic biological psychology concepts.
This material covers how psychologists define, classify, and explain mental disorders. It spans the major diagnostic frameworks (DSM-5, diathesis-stress model, biopsychosocial perspective), the main categories of disorders you are expected to know for Exam 3 (anxiety, mood, psychotic, personality, and neurodevelopmental disorders), and the symptoms that distinguish them. This is one of the most heavily tested areas because it combines terminology recall with the ability to apply diagnostic criteria to case vignettes. If you have not reviewed the personality theories notes, do so first: personality disorders build directly on that material.
Psychological disorders are understood through models that combine genetic vulnerability with environmental stress (diathesis-stress) or integrate biological, psychological, and social factors (biopsychosocial). The DSM-5 is the standard classification system. You need to know the key features of anxiety disorders (GAD, panic, phobias, OCD, PTSD), mood disorders (major depression, bipolar), schizophrenia (hallucinations, delusions, disorganised thinking), personality disorders (narcissistic, antisocial), and neurodevelopmental disorders (ASD, ADHD, conduct disorder).
Diathesis-Stress Model
A framework proposing that psychological disorders result from the interaction between a genetic or biological predisposition (diathesis) and environmental stressors. In simple terms, you may carry a vulnerability, but the disorder emerges only when life circumstances trigger it.
Biopsychosocial Perspective
An integrative approach that considers biological (genetics, brain chemistry), psychological (thoughts, emotions, coping), and social (relationships, culture, socioeconomic status) factors in understanding mental health. Think of it as the "no single cause" model.
DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition)
The standard classification system for mental disorders used by clinicians in the United States and widely referenced internationally. In simple terms, it is the reference book that defines what counts as a diagnosable mental disorder and lists the criteria for each one.
Comorbidity
The co-occurrence of two or more disorders in the same individual at the same time. In simple terms, having depression and an anxiety disorder simultaneously is comorbidity.
Panic Disorder
An anxiety disorder characterised by sudden, intense episodes of fear (panic attacks) that include physical symptoms such as heart pounding, shortness of breath, and dizziness. Think of it as the body's alarm system firing when there is no actual danger.
Phobic Disorders (Specific Phobias)
Anxiety disorders involving irrational, persistent fears of specific objects or situations (e.g., spiders, heights, flying). In simple terms, a fear response that is out of proportion to the actual threat.
Obsessive-Compulsive Disorder (OCD)
A disorder characterised by intrusive, unwanted thoughts (obsessions) and repetitive behaviours or mental acts (compulsions) performed to reduce the anxiety caused by the obsessions. Think of it as being stuck in a loop: the thought creates anxiety, the ritual briefly reduces it, but the thought returns.
Posttraumatic Stress Disorder (PTSD)
A disorder that can develop after exposure to a traumatic event, featuring persistent distress, intrusive memories, avoidance of reminders, negative changes in mood and cognition, and heightened arousal. In simple terms, the traumatic experience keeps replaying and the person cannot move past it.
Generalised Anxiety Disorder (GAD)
Chronic, excessive worry about multiple aspects of life (health, finances, work, family) that is difficult to control and persists for at least six months. Think of it as a worry dial stuck on high across many areas, not focused on any single trigger.
Major Depressive Disorder (MDD)
A mood disorder characterised by persistent sadness, loss of interest or pleasure in activities, changes in appetite and sleep, fatigue, difficulty concentrating, and feelings of worthlessness or guilt. In simple terms, a sustained low mood that interferes with daily functioning, lasting at least two weeks.
Bipolar Disorder
A mood disorder involving alternating episodes of depression and mania (or hypomania). Manic episodes feature elevated mood, increased energy, reduced need for sleep, grandiosity, and impulsive behaviour. Think of it as mood cycling between extreme lows and extreme highs.
Schizophrenia
A severe disorder involving positive symptoms (hallucinations, delusions, disorganised thinking and speech) and negative symptoms (flat affect, withdrawal, reduced motivation). In simple terms, a condition that disrupts a person's ability to distinguish what is real from what is not.
Hallucinations
Sensory perceptions that occur without any external stimulus. They can involve any sense but auditory hallucinations (hearing voices) are most common in schizophrenia.
Delusions
Strongly held false beliefs that persist despite contradicting evidence. Common types include delusions of persecution (believing others intend harm) and delusions of grandeur (believing you have exceptional abilities or status).
Narcissistic Personality Disorder
A personality disorder characterised by grandiosity, a need for admiration, and a lack of empathy. In simple terms, an inflated self-image paired with difficulty recognising other people's feelings or needs.
Antisocial Personality Disorder
A personality disorder characterised by a persistent pattern of disregard for others' rights, deceitfulness, impulsivity, and lack of remorse. Think of it as a pattern of rule-breaking and exploitation that begins in adolescence and continues into adulthood.
Autism Spectrum Disorder (ASD)
A neurodevelopmental disorder characterised by differences in social interaction and communication, alongside restricted or repetitive patterns of behaviour, interests, or activities. In simple terms, it is a spectrum: some individuals need substantial support, others function independently with specific challenges.
ADHD (Attention-Deficit/Hyperactivity Disorder)
A neurodevelopmental disorder featuring persistent patterns of inattention, hyperactivity, and impulsivity that interfere with functioning or development. Think of it as difficulty regulating attention and impulses, not a lack of intelligence or effort.
Conduct Disorder
A pattern of aggressive and rule-breaking behaviour in children and adolescents, including bullying, property destruction, deceitfulness, and violation of rules. In simple terms, persistent serious behavioural problems that go beyond typical childhood misbehaviour.
Diathesis-stress model
Disorder = predisposition + trigger. Neither alone is sufficient.
The diathesis can be genetic, biological, or psychological (e.g., a temperament trait)
The stressor can be acute (a traumatic event) or chronic (ongoing poverty, abuse)
Biopsychosocial perspective
Biological: genetics, neurotransmitter imbalances, brain structure
Psychological: cognitive patterns, learned behaviours, coping styles
Social: family environment, cultural expectations, socioeconomic status
This is the dominant framework in modern clinical psychology and psychiatry
DSM-5
Provides standardised diagnostic criteria so clinicians can communicate reliably
Organised by disorder categories (anxiety, mood, psychotic, personality, neurodevelopmental, etc.)
Does not explain causes; it describes symptoms and sets thresholds for diagnosis
Generalised Anxiety Disorder (GAD): persistent, excessive worry across many domains; lasts at least six months; often accompanied by muscle tension, restlessness, and fatigue
Panic Disorder: recurrent, unexpected panic attacks plus ongoing fear of future attacks
Specific Phobias: intense, irrational fear of a particular object or situation; avoidance is the primary coping mechanism
OCD: obsessions (intrusive thoughts) drive compulsions (rituals). The compulsion temporarily reduces anxiety but reinforces the cycle.
PTSD: follows a traumatic event. Four symptom clusters: intrusive memories, avoidance, negative changes in cognition/mood, and hyperarousal.
Major Depressive Disorder
Core symptoms: depressed mood and/or loss of interest/pleasure, most of the day, nearly every day, for at least two weeks
Additional symptoms: appetite/weight changes, sleep disturbance, fatigue, worthlessness, difficulty concentrating, suicidal ideation
Most common mood disorder; twice as prevalent in women
Bipolar Disorder
Cycling between depressive and manic (or hypomanic) episodes
Mania: elevated or irritable mood, increased energy, decreased sleep, grandiosity, risky behaviour
Bipolar I involves full manic episodes; Bipolar II involves hypomanic episodes (less severe)
Positive symptoms (things added to normal experience): hallucinations, delusions, disorganised speech and behaviour
Negative symptoms (things subtracted from normal experience): flat affect, social withdrawal, avolition (reduced motivation), alogia (reduced speech)
Onset typically in late adolescence or early adulthood
Strong genetic component, but environmental factors (prenatal stress, substance use) contribute
Long-standing, inflexible patterns of behaviour that deviate from cultural expectations and cause impairment
Narcissistic: grandiosity, need for admiration, lack of empathy
Antisocial: disregard for others' rights, deceitfulness, impulsivity, lack of remorse. Conduct disorder in childhood is often a precursor.
ASD: social communication differences and restricted/repetitive behaviours. A spectrum, ranging from those who need significant support to those who function independently.
ADHD: inattention, hyperactivity, and impulsivity. Three presentations: predominantly inattentive, predominantly hyperactive-impulsive, and combined.
Conduct Disorder: aggression, property destruction, deceitfulness, rule violations. Can precede antisocial personality disorder in adulthood.
The biopsychosocial model is the standard framework used in clinical settings to develop treatment plans that address multiple contributing factors. The DSM-5 criteria determine whether insurance will cover treatment. Understanding PTSD symptoms has shaped policy for military veterans and trauma survivors. ADHD diagnosis influences academic accommodations and workplace support.
Students often confuse the diathesis-stress model with the biopsychosocial perspective. The diathesis-stress model focuses specifically on the interaction between predisposition and stress as a trigger. The biopsychosocial perspective is broader: it considers biological, psychological, and social factors without requiring a specific trigger event.
Students frequently think OCD is just about being neat or organised. Clinical OCD involves distressing, intrusive thoughts and time-consuming rituals that significantly impair daily life.
Students sometimes believe schizophrenia means "split personality." It does not. Schizophrenia involves psychotic symptoms (hallucinations, delusions); dissociative identity disorder is the condition sometimes called split personality.
Students often assume bipolar disorder means rapid mood swings within a single day. Manic and depressive episodes typically last days to weeks, not hours.
⚠️ Be able to match each anxiety disorder to its defining feature in a vignette (e.g., intrusive thoughts + rituals = OCD; persistent worry across many domains = GAD; sudden intense fear episodes = panic disorder).
⚠️ Know the difference between positive and negative symptoms in schizophrenia. Exam questions often ask you to classify a listed symptom as one or the other.
⚠️ Understand why comorbidity matters clinically: a patient with both depression and GAD may need a different treatment approach than someone with either alone.
⚠️ Be able to distinguish antisocial personality disorder from conduct disorder by age of the individual (conduct disorder is diagnosed in children/adolescents; antisocial personality disorder in adults).
True or False: The DSM-5 explains the causes of mental disorders.
Answer: False. It describes symptoms and provides diagnostic criteria but does not explain aetiology.
Fill in the blank: In the diathesis-stress model, a disorder results from the interaction between a ______ and environmental ______.
Answer: Predisposition (diathesis); stress.
True or False: Hallucinations are a negative symptom of schizophrenia.
Answer: False. They are a positive symptom (something added to normal experience).
Fill in the blank: The mood disorder characterised by alternating episodes of depression and mania is called ______ disorder.
Answer: Bipolar.
True or False: Conduct disorder in children can be a precursor to antisocial personality disorder in adulthood.
Answer: True.
Q: A 25-year-old woman experiences intrusive thoughts about contamination and washes her hands dozens of times per day, causing skin damage. Which disorder does this most closely describe, and what are the obsessions and compulsions?
A: Obsessive-compulsive disorder (OCD). The obsession is the intrusive thought about contamination. The compulsion is the repeated hand-washing, performed to reduce the anxiety caused by the obsession.
Q: A patient reports hearing voices that comment on his behaviour, believes the government is monitoring his thoughts, and has become increasingly withdrawn. Which disorder is most likely, and which symptoms are positive vs. negative?
A: Schizophrenia. Positive symptoms: auditory hallucinations (hearing voices) and delusions (government monitoring). Negative symptom: social withdrawal.
Q: Explain the diathesis-stress model using depression as an example.
A: A person may carry a genetic vulnerability to depression (the diathesis). If they experience a major life stressor such as job loss or bereavement, the interaction between the predisposition and the stressor can trigger a depressive episode. Neither the genetic vulnerability alone nor the stressor alone would necessarily produce the disorder.
Q: What is the key difference between GAD and panic disorder?
A: GAD involves chronic, excessive worry across multiple areas of life. Panic disorder involves sudden, discrete episodes of intense fear (panic attacks) that are not tied to a specific ongoing worry.
Q: A 10-year-old boy has been bullying classmates, vandalising school property, and lying to teachers for over a year. Which disorder should be considered?
A: Conduct disorder. It involves a persistent pattern of aggression, property destruction, deceitfulness, and rule violation in children and adolescents.
The personality disorders material here connects back to the trait and psychodynamic perspectives covered in the personality theories notes. The biopsychosocial model also bridges to health psychology and coping (covered in the next set of notes), where stress, optimism, and perceived control are examined as factors that influence both physical and mental health outcomes. Comorbidity is relevant to understanding treatment approaches covered in the treatment and health psychology notes.
Psychological disorders, mental illness, DSM-5, diathesis-stress, biopsychosocial, comorbidity, anxiety disorders, GAD, generalised anxiety disorder, panic disorder, panic attacks, phobias, specific phobia, OCD, obsessive-compulsive disorder, PTSD, posttraumatic stress disorder, mood disorders, major depressive disorder, MDD, depression, bipolar disorder, mania, hypomania, schizophrenia, hallucinations, delusions, positive symptoms, negative symptoms, personality disorders, narcissistic personality disorder, antisocial personality disorder, neurodevelopmental disorders, autism spectrum disorder, ASD, ADHD, attention-deficit/hyperactivity disorder, conduct disorder, psychopathology, abnormal psychology, PSY II, Florida International University, Exam 3