Difficulty: Intermediate to Advanced | Prerequisites: Chapters 4, 6, 7, and 10 (brain regions, conditioning, memory, stress).
This chapter covers how mental disorders are classified, assessed, and understood. It draws on nearly everything from earlier chapters: brain anatomy (Ch. 4), learning and conditioning (Ch. 6), memory (Ch. 7), and emotions and stress (Ch. 10). The central theme is that most mental disorders arise from a combination of biological predispositions and environmental factors (the diathesis-stress model). Understanding the DSM classification system, the major disorder categories, and their cognitive, biological, and situational components is the capstone of the course.
Mental disorders are classified using the DSM, which describes disorders in terms of observable symptoms. They are assessed through clinical interviews, behavioural observations, and psychological testing. Anxiety disorders (phobias, GAD, panic, OCD) involve excessive fear in the absence of real danger. Mood disorders (major depression, bipolar) involve extreme emotional states. Schizophrenia is a psychotic disorder with positive symptoms (delusions, hallucinations) and negative symptoms (apathy, flat affect). Personality disorders (borderline, antisocial) are enduring, maladaptive patterns. The diathesis-stress model integrates biological vulnerability with environmental triggers.
Psychopathology
The sickness or disorder of the mind. Arises from both biological predispositions and environmental factors.
DSM (Diagnostic and Statistical Manual of Mental Disorders)
First published in 1952. The current edition describes disorders by observable symptoms and diagnostic criteria. Uses the multiaxial system (five axes for a complete picture).
Assessment / mental status exam
Examination of a person's mental state: grooming, eye contact, tremors, mood, speech, thought, memory.
Clinical interview
Questions about past experiences and current feelings to reach a diagnosis. Can be structured (standardised, comparable) or unstructured (flexible).
MMPI (Minnesota Multiphasic Personality Inventory)
A series of true/false questions that can classify a patient into diagnostic categories and assess response validity.
Family systems model
Behaviour must be considered within a social context, particularly the family.
Sociocultural model
Psychopathology results from the interaction between individuals and their cultures (schizophrenia more common in lower classes; anorexia more common in upper/middle classes).
Cognitive behavioural approach
Psychopathology results from learned maladaptive cognitions, based on observable variables.
Diathesis-stress model
A disorder develops when an underlying biological vulnerability (diathesis) is coupled with a precipitating environmental event (stress).
Anxiety disorders
Excessive anxiety in the absence of true danger.
Specific phobia
Fear of a particular object or situation.
Social phobia
Fear of being negatively evaluated by others.
Generalised anxiety disorder (GAD)
A diffuse state of constant anxiety not associated with a specific object or event.
Panic disorder
Sudden, overwhelming attacks of terror; can be cued internally or externally. Related to agoraphobia.
Agoraphobia
Fear of situations in which escape may be difficult or impossible.
OCD (Obsessive Compulsive Disorder)
Frequent intrusive thoughts (obsessions) and repetitive, somewhat uncontrollable actions (compulsions).
Major depression
Severe negative moods and lack of interest in normally pleasurable activities. Lasts ~6 months; 90% recover but 50% have a repeated episode.
Dysthymia
A less severe form of depression, lasting at least 2 years. Some consider it a personality disorder.
Bipolar disorder
Alternating periods of depression and mania. Manic episodes: elevated mood, reduced need for sleep, grandiose ideas. Bipolar II involves hypomania (heightened creativity and productivity). Cyclothymia alternates between hypomania and mild depression.
Learned helplessness model
A cognitive model of depression in which people feel unable to control events around them and expect bad things to continue happening.
Seasonal affective disorder (SAD)
Depression corresponding to shorter winter days. Treated with artificial light to reset biological rhythms.
Schizophrenia
A psychotic disorder characterised by alterations in perceptions, emotions, thoughts, or consciousness. Literally "splitting of the mind."
Positive symptoms (schizophrenia)
Excesses in behaviour: delusions (false personal beliefs), hallucinations (false sensory perceptions), loosening of associations (disorganised speech).
Negative symptoms (schizophrenia)
Deficits in functioning: apathy, lack of emotion, slowed speech and movement. More common in men; may be a different disorder entirely.
Personality disorder
Inflexible, maladaptive ways of interacting with the world, lasting the whole life span.
Borderline personality disorder (BPD)
Identity, affective, and impulse disturbances. Dependent on relationships; episodes of anxiety, depression, anger; impulsive behaviour including self-mutilation. Linked to serotonin and often to childhood abuse.
Antisocial personality disorder (APD)
Lack of empathy and remorse; immediate gratification seeking; repeated criminal acts. Diagnosis cannot be made before age 18; tends to remit around age 40. 40-75% of prisoners estimated to have it.
Autism
Developmental disorder: deficits in social interaction, impaired communication, restricted interests. Ranges from mild (Asperger's) to severe.
ADHD (Attention Deficit Hyperactivity Disorder)
Restless, inattentive, and impulsive behaviour. Clearly genetic; impaired frontal lobes and limbic systems.
Dissociative identity disorder (DID)
Multiple personality disorder; may be attributed to early-life abuse where the person mentally removes themselves from traumatic situations.
Forensic psychology
Psychologists who work within the legal system: assessing defendant competency, assisting in custody disputes, profiling criminals.
Criteria for disorder: behaviour deviates from cultural norms, is maladaptive, causes the individual distress, and interferes with work, social life, or self-care
First comprehensive classification by Emil Kraepelin; DSM published in 1952, evolved through several editions
Current DSM describes disorders by observable symptoms and diagnostic criteria (multiaxial system: five axes for a complete picture)
Assessment tools: mental status exam (grooming, eye contact, mood, speech, thought, memory), clinical interviews (structured vs. unstructured), behavioural assessments (observing irregularities), psychological testing (MMPI)
Psychological factors: family systems model (behaviour in social/family context), sociocultural model (interaction with culture)
Cognitive behavioural approach: maladaptive cognitions learned through conditioning
Biological factors: genetics, malnutrition, maternal illness, toxin exposure, brain structure differences (neuroimaging), neurotransmitter imbalances
Diathesis-stress model: underlying vulnerability + precipitating event = disorder; the integrating framework
General features: tension, apprehension, depression, irritability; impaired sleep, attention, problem-solving; autonomic arousal (sweating, dry mouth, rapid pulse); can cause hippocampal atrophy
Specific phobia: fear of particular objects/situations; social phobia: fear of negative evaluation
GAD: constant, diffuse anxiety without a specific trigger; fatigue, irritability, headaches
Panic disorder: sudden terror attacks; heart racing, dizziness, shortness of breath; linked to agoraphobia (catastrophic thinking about inability to escape leads to avoidance)
OCD: obsessions (intrusive thoughts) + compulsions (repetitive acts to reduce anxiety); paradoxically, people are aware of their OCD; etiology partly genetic, linked to dysfunctional caudate nucleus (basal ganglia); streptococcal infection can also cause it; caudate damage makes prefrontal cortex overactive, establishing obsession-compulsion associations
Cognitive, situational, and biological components: negative perception of neutral situations, observational fear learning, inhibited temperament in infancy
Panic attacks are more biological (CNS arousal abnormalities); agoraphobia requires cognitive behavioural therapy, not just medication
Major depression: severe negative mood, anhedonia, appetite loss, sleep disturbances, guilt, thoughts of death; ~6 months duration; 90% recover, 50% relapse
Dysthymia: less severe but lasts at least 2 years; some consider it a personality disorder; often leads to major depression
Bipolar disorder: alternating depression and mania (elevated mood, grandiosity, racing thoughts, reduced sleep need); bipolar II involves hypomania; cyclothymia alternates hypomania and mild depression
Causes of depression: genetic component; less norepinephrine; damage to left prefrontal cortex; abnormal REM cycles and body temperature; seasonal affective disorder (treated with light therapy); personal loss and lack of social support; cognitive distortions (negative triad: self, situation, future); learned helplessness (expecting uncontrollable bad events)
Bipolar is strongly biological: genetic evidence from Amish studies; successive generations show earlier onset and greater severity
A psychotic disorder: alterations in perception, emotion, thought, consciousness
Positive symptoms: delusions (false beliefs), hallucinations (false perceptions, often auditory; linked to inner speech brain areas), loosening of associations (disorganised speech), disorganised behaviour (echolalia, catatonia)
Negative symptoms: apathy, flat affect, slowed speech/movement; more common in men; may be a separate disorder; tend to persist after positive symptoms are treated
Primarily a brain disorder: genetic predisposition; enlarged ventricles (reduced brain tissue); dopamine increases symptoms; possible myelin sheath abnormalities; early childhood behavioural signs predict later diagnosis
Environmental factors: urban upbringing doubles risk; adopted children of schizophrenic parents have 30% higher risk if adoptive family is disturbed; 2nd trimester maternal influenza increases risk; late-splitting (mirrored) twins sharing a placenta have higher concordance
Enduring, inflexible, maladaptive patterns; last the whole life span
Three groups: (1) odd/eccentric, (2) dramatic/emotional/erratic, (3) anxious/fearful
Borderline personality disorder (BPD): identity, affective, and impulse disturbances; relationship dependency and manipulation; impulsive behaviour including self-mutilation; high suicide risk; linked to serotonin; childhood abuse and caregiver rejection are common precursors
Antisocial personality disorder (APD): lack of empathy/remorse; hedonistic; repeated criminal acts; cannot be diagnosed before age 18; tends to remit around 40; 40-75% of prisoners; slower alpha wave activity, low arousal, smaller amygdala, frontal lobe deficits
Autism: deficits in social interaction, impaired communication, restricted interests; ranges from Asperger's to severe impairments; avoids eye contact, focuses on objects; echolalia, pronoun reversal; ritualistic behaviour; unusually fast then slowed brain growth; possible oxytocin deficit
ADHD: restless, inattentive, impulsive; clearly genetic; impaired frontal lobes and limbic systems; basal ganglia differences; sometimes outgrown, sometimes lifelong
Legal insanity: inability to appreciate the criminality of the act or conform to the law due to a mental disorder; burden of proof shifted to the defence after the Hinckley verdict
Forensic psychologists: assess defendant competency, assist in custody disputes, profile criminals, design correctional facilities
The diathesis-stress model explains why some people develop disorders after trauma while others do not. Cognitive behavioural therapy (CBT) is the evidence-based treatment for many anxiety and mood disorders, directly applying the cognitive behavioural approach from this chapter. Understanding the biological basis of schizophrenia has led to antipsychotic medications targeting dopamine pathways.
Students think schizophrenia means "split personality." It means "splitting of the mind" (fragmented thought), not multiple personalities (that is DID).
Students assume personality disorders are just extreme personality traits. They are maladaptive patterns that persist across the life span and cause significant impairment in work and relationships.
Students think depression is just sadness. Major depression involves anhedonia, sleep disturbance, appetite changes, guilt, concentration problems, and thoughts of death, lasting at least six months.
Students confuse positive and negative symptoms of schizophrenia. Positive symptoms are additions (delusions, hallucinations); negative symptoms are subtractions (flat affect, apathy).
⚠️ Know the diathesis-stress model and be able to apply it to any disorder.
⚠️ Be able to distinguish between positive and negative symptoms of schizophrenia, with examples.
⚠️ Understand OCD: obsessions are thoughts, compulsions are acts; the caudate nucleus and prefrontal cortex are implicated.
⚠️ Know the difference between major depression, dysthymia, bipolar I, and bipolar II.
⚠️ Borderline personality disorder vs. antisocial personality disorder: know the key features and brain correlates of each.
⚠️ The learned helplessness model of depression is a favourite exam topic.
Fill in the blank: The __________ model proposes that mental disorders arise when a biological vulnerability is coupled with an environmental stressor. (Diathesis-stress)
True or False: Positive symptoms of schizophrenia include apathy and flat affect. (False. Those are negative symptoms. Positive symptoms include delusions and hallucinations.)
Fill in the blank: In OCD, the intrusive thoughts are called __________ and the repetitive acts are called __________. (Obsessions; compulsions)
True or False: Antisocial personality disorder can be diagnosed in children under 18. (False. Diagnosis cannot be made before age 18.)
Fill in the blank: The cognitive model of depression in which people feel unable to control events is called __________. (Learned helplessness)
Q: Explain the diathesis-stress model and give an example of how it applies to depression.
A: The diathesis-stress model proposes that a disorder develops when an underlying biological vulnerability (diathesis) is coupled with a precipitating environmental event (stress). For depression, the diathesis could be a genetic predisposition (family history, reduced norepinephrine) and the stressor could be personal loss or chronic stress. Neither the vulnerability nor the stressor alone is sufficient; both are needed for the disorder to emerge.
Q: Compare and contrast the positive and negative symptoms of schizophrenia.
A: Positive symptoms are excesses or additions to normal behaviour, including delusions (false personal beliefs), hallucinations (false sensory perceptions, often auditory), and loosening of associations (disorganised speech). Negative symptoms are deficits in functioning, including apathy, flat affect, and slowed speech and movement. Positive symptoms tend to respond to medication; negative symptoms are more persistent and may represent a different disorder. Negative symptoms are more common in men.
Q: Describe borderline personality disorder and antisocial personality disorder. How do their key features and brain correlates differ?
A: BPD is characterised by identity, affective, and impulse disturbances; dependency on relationships; frequent episodes of anxiety, depression, and anger; and impulsive behaviour including self-mutilation. It is linked to serotonin dysfunction and often to childhood abuse. APD is characterised by lack of empathy and remorse, hedonistic behaviour, and repeated criminal acts. It is linked to slower alpha wave activity, low arousal, a smaller amygdala, and frontal lobe deficits. BPD involves intense emotional volatility; APD involves emotional flatness and disregard for others.
Q: What is OCD, and how is it both cognitive and biological?
A: OCD involves intrusive, unwanted thoughts (obsessions) and repetitive actions performed to reduce anxiety (compulsions). Cognitively, the compulsion is reinforced because it temporarily reduces the anxiety caused by the obsession, making the compulsion more likely to recur. Biologically, OCD is linked to dysfunction of the caudate nucleus (part of the basal ganglia, which suppresses impulses); caudate damage makes the prefrontal cortex overactive, establishing associations between obsessive thoughts and compulsive behaviours. It also has a genetic component and can be triggered by streptococcal infection.
Anxiety disorders connect to fear conditioning and the amygdala (Chs. 4 and 6). Mood disorders connect to neurotransmitters and brain regions from Chapter 4, and to stress and coping from Chapter 10 (depression often follows chronic stress). Schizophrenia ties to dopamine and brain structure (Ch. 4). The cognitive behavioural approach draws on classical and operant conditioning (Ch. 6). The diathesis-stress model integrates biological vulnerability (Ch. 4) with environmental stressors (Ch. 10).
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