Module 4: Psychological Disorders

Overview of Psychological Disorders

Psychological disorders, also known as mental disorders or psychopathologies, refer to patterns of thoughts, feelings, or behaviors that are deviant, distressing, dysfunctional, and sometimes dangerous. These conditions disrupt daily functioning, impair quality of life, and often require clinical attention. The MCAT approaches psychological disorders from a biopsychosocial perspective, focusing on how biological, psychological, and sociocultural factors interact to influence the onset, presentation, and treatment of mental illness.

Core Components of Mental Illness

The 4 D’s often help define abnormality:

Deviance – Behavior or thoughts that differ markedly from societal norms.
Distress – Subjective discomfort or suffering experienced by the individual.
Dysfunction – Interference with daily functioning (work, relationships, self-care).
Danger – Risk of harm to self or others (less common but clinically relevant).

It’s important to distinguish between normal variations in emotion or behavior and clinically significant mental illness. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) is the standard tool used by clinicians to define and classify disorders based on symptom criteria and duration.

The MCAT emphasizes:

Diagnostic categories and symptom profiles
Biopsychosocial contributors
Cultural influences on diagnosis and treatment
Stigma and access to care

Common Themes Across Disorders

Biological Underpinnings: Many disorders are associated with neurotransmitter imbalances (e.g., serotonin, dopamine), structural brain abnormalities, or genetic predispositions.
Psychological Factors: Stress, trauma, learned behaviors, and cognitive distortions can contribute to the development and persistence of disorders.
Sociocultural Factors: Discrimination, socioeconomic status, family dynamics, and cultural norms influence symptom expression and access to care.

Anxiety Disorders

Anxiety disorders are characterized by excessive fear, worry, or nervousness that is disproportionate to the actual threat or stressor. While mild anxiety can be adaptive (e.g., improving performance before an exam), clinical anxiety is chronic, disruptive, and impairs functioning.

The DSM-5 categorizes anxiety disorders as a distinct class, separate from obsessive-compulsive and trauma-related disorders (which are covered in their own categories).

Common Anxiety Disorders:

Disorder	Key Features	MCAT Notes
Generalized Anxiety Disorder (GAD)	Persistent, excessive worry about various life aspects (work, health, relationships) for 6+ months	No specific trigger; often associated with physical symptoms like restlessness, fatigue, irritability
Panic Disorder	Recurrent, unexpected panic attacks (sudden episodes of intense fear with physical symptoms)	Panic attacks include heart palpitations, sweating, shortness of breath; may lead to fear of future attacks
Social Anxiety Disorder (Social Phobia)	Intense fear of being judged or embarrassed in social situations	Avoidance of social settings; may overlap with avoidant personality disorder
Specific Phobia	Intense, irrational fear of a specific object or situation (e.g., heights, spiders, flying)	Often leads to avoidance behavior; insight into irrationality does not reduce fear
Agoraphobia	Fear of situations where escape is difficult or help may not be available (e.g., crowds, open spaces)	Commonly co-occurs with panic disorder

Neurobiology and Risk Factors

Amygdala Hyperactivity: Increased activity in fear-related brain circuits, especially the amygdala.
Low GABA levels: Inhibitory neurotransmitter GABA helps calm the brain — reduced levels may contribute to anxiety.
Genetics: Family history is a risk factor, though environmental influences also play a major role.
Behavioral Learning: Classical conditioning (e.g., fear learning), operant conditioning (avoidance reinforcement), and observational learning all play roles.

Treatment Approaches

Cognitive Behavioral Therapy (CBT): Most effective psychotherapy for anxiety; targets maladaptive thought patterns and avoidance behaviors.
Pharmacological Interventions:
- SSRIs (e.g., fluoxetine) and SNRIs for long-term symptom reduction
- Benzodiazepines (e.g., lorazepam) for acute anxiety episodes (short-term only)
Mindfulness and Exposure Therapy: Especially effective for phobias and social anxiety

Obsessive-Compulsive and Related Disorders

Obsessive-compulsive and related disorders involve intrusive, unwanted thoughts (obsessions) and/or repetitive behaviors (compulsions) that are performed to reduce distress. These disorders are distinct from anxiety disorders in the DSM-5 but share overlapping features such as distress and avoidance behaviors.

Key Terms

Obsession: Recurrent, intrusive thoughts, urges, or images that cause distress
Compulsion: Repetitive behaviors or mental acts performed to reduce anxiety or prevent a feared event

Major Disorders in This Category:

Disorder	Description	MCAT Notes
Obsessive-Compulsive Disorder (OCD)	Characterized by time-consuming obsessions and/or compulsions that impair functioning	Common obsessions include contamination, symmetry, and harm; compulsions include cleaning, checking, counting
Body Dysmorphic Disorder	Preoccupation with perceived physical defects or flaws that are not observable or appear slight to others	Often leads to excessive mirror checking, grooming, or cosmetic procedures
Hoarding Disorder	Persistent difficulty discarding possessions, regardless of actual value	Results in cluttered living spaces and significant distress or impairment
Trichotillomania (Hair-Pulling Disorder)	Recurrent pulling out of one’s hair, resulting in hair loss	Can involve scalp, eyebrows, eyelashes; often preceded by tension and followed by relief
Excoriation (Skin-Picking) Disorder	Recurrent skin picking resulting in lesions	Often affects the face, arms, or hands; may be triggered by stress or anxiety

Neurobiological Correlates

Cortico-striato-thalamo-cortical (CSTC) loop dysfunction: Associated with obsessive-compulsive behavior
Serotonin Dysregulation: Especially in OCD, SSRIs are often first-line treatment

Treatment Strategies

CBT with Exposure and Response Prevention (ERP): Gold-standard therapy for OCD and related disorders
SSRIs: Often used in moderate to severe OCD cases
Habit Reversal Training: Effective for trichotillomania and excoriation

t follow exposure to a traumatic or highly stressful event. Unlike anxiety disorders, which often arise without a specific external trigger, these disorders stem from a clearly identifiable life event.

Core Features

Exposure to actual or threatened death, serious injury, or sexual violence (either direct or indirect)
Involuntary re-experiencing of the trauma
Emotional numbing or heightened reactivity
Avoidance of trauma-related stimuli

Major Disorders in This Category

Disorder	Key Characteristics	MCAT Notes
Post-Traumatic Stress Disorder (PTSD)	Persistent symptoms lasting >1 month after trauma exposure: intrusive memories, nightmares, hypervigilance, emotional detachment	Common among veterans, survivors of assault or disasters; symptoms must significantly impair function
Acute Stress Disorder	Similar symptoms as PTSD but duration is 3 days to 1 month post-trauma	May progress to PTSD if symptoms persist
Adjustment Disorder	Emotional/behavioral symptoms in response to a major life stressor (e.g., divorce, job loss) within 3 months	Less severe than PTSD; symptoms resolve when stressor or consequences subside
Reactive Attachment Disorder	Occurs in children; emotionally withdrawn behavior toward adult caregivers following extreme neglect	Rare; requires evidence of insufficient care
Disinhibited Social Engagement Disorder (DSED)	In children; overly familiar behavior with strangers due to neglect or inconsistent caregiving	Associated with institutionalized children (e.g., orphanages)

Neurobiology and Risk Factors

HPA Axis Dysregulation: Chronic stress disrupts the hypothalamic-pituitary-adrenal (HPA) axis, elevating cortisol levels
Amygdala Hyperactivity: Heightened fear responses and emotional memory
Low Hippocampal Volume: Linked to difficulty contextualizing trauma memories
Risk Factors: Prior trauma, lack of social support, childhood adversity, and genetic vulnerability

Treatment Approaches

Trauma-Focused CBT: Helps patients process and reframe traumatic memories
EMDR (Eye Movement Desensitization and Reprocessing): Used for PTSD; patient recalls trauma while undergoing bilateral stimulation (e.g., eye movements)
SSRIs and SNRIs: First-line pharmacotherapy for PTSD
Crisis Intervention and Supportive Therapy: Often used in acute stress or adjustment disorders

Depressive Disorders

Depressive disorders are characterized by pervasive low mood, anhedonia (loss of interest or pleasure), and associated cognitive and physical symptoms. These conditions significantly impair daily functioning and are among the most common mental health issues worldwide.

Core Symptoms

Depressed mood most of the day, nearly every day
Anhedonia: diminished interest or pleasure in activities
Fatigue or loss of energy
Feelings of worthlessness or excessive guilt
Difficulty concentrating or indecisiveness
Insomnia or hypersomnia
Psychomotor agitation or retardation
Significant weight loss or gain
Recurrent thoughts of death or suicide

Symptoms must persist for at least two weeks and cause significant distress or impairment to meet DSM-5 criteria.

Major Types of Depressive Disorders

Disorder	Key Characteristics	MCAT Notes
Major Depressive Disorder (MDD)	≥5 symptoms present for ≥2 weeks, including depressed mood and/or anhedonia	Most common; may be single episode or recurrent
Persistent Depressive Disorder (Dysthymia)	Depressed mood for most days over ≥2 years (1 year in children)	Chronic but typically less severe than MDD
Premenstrual Dysphoric Disorder (PMDD)	Mood swings, irritability, and depressive symptoms in the luteal phase of menstrual cycle	Distinct from PMS; significantly disrupts functioning
Disruptive Mood Dysregulation Disorder (DMDD)	Severe temper outbursts and chronic irritability in children (ages 6–18)	Created to reduce overdiagnosis of bipolar disorder in youth
Seasonal Affective Disorder (SAD)	Depression onset during fall/winter, remission in spring	Related to decreased sunlight; responds to light therapy

Biological and Psychological Correlates

Monoamine Hypothesis: Decreased serotonin, norepinephrine, and dopamine activity
HPA Axis Hyperactivity: Elevated cortisol associated with stress-related depression
Neuroanatomy: Altered function in the prefrontal cortex, hippocampus, and amygdala
Learned Helplessness: Repeated exposure to uncontrollable stress may reduce motivation and cause depressive symptoms
Negative Cognitive Triad (Beck): Negative views about the self, the world, and the future

Treatment Approaches

Pharmacotherapy:
- SSRIs (e.g., fluoxetine)
- SNRIs and atypical antidepressants
- Tricyclics and MAOIs (used less due to side effects)
Psychotherapy:
- Cognitive Behavioral Therapy (CBT)
- Interpersonal Therapy (IPT)
Other Modalities:
- Electroconvulsive Therapy (ECT) for treatment-resistant depression
- Transcranial Magnetic Stimulation (TMS)
- Light Therapy for SAD

Bipolar and Related Disorders

Bipolar and related disorders are characterized by cyclical, extreme disturbances in mood that involve periods of abnormally elevated energy (mania or hypomania) and, often, depressive episodes. These disorders differ from unipolar depression by the presence of manic or hypomanic episodes and can significantly impair functioning, relationships, and quality of life.

Core Mood States

Mania: A state of persistently elevated, expansive, or irritable mood lasting at least 1 week (or any duration if hospitalization is required). Key symptoms include:
- Inflated self-esteem or grandiosity
- Decreased need for sleep (e.g., feeling rested after only 2 hours)
- Increased talkativeness or pressure to keep talking
- Flight of ideas or subjective experience of racing thoughts
- Distractibility
- Increased goal-directed activity or psychomotor agitation
- Excessive involvement in risky activities (e.g., unrestrained spending, sexual indiscretions) Mania often requires hospitalization and may include psychotic features.
Hypomania: A milder form of mania lasting at least 4 consecutive days, not severe enough to cause marked impairment or require hospitalization. Psychotic features are absent. Hypomania may still be noticeable to others and lead to functional challenges.
Major Depressive Episode: See Section 5. Often follows or alternates with manic/hypomanic episodes in bipolar disorders.

Major Types of Bipolar Disorders

Disorder	Key Diagnostic Features	MCAT Notes
Bipolar I Disorder	At least 1 manic episode; depressive episodes are common but not required for diagnosis	Classic form of bipolar disorder. Manic episodes are the hallmark feature
Bipolar II Disorder	At least 1 hypomanic episode and 1 major depressive episode; no history of full mania	Depressive symptoms dominate; misdiagnosis as unipolar depression is common
Cyclothymic Disorder	2+ years of fluctuating mood disturbances, with numerous periods of subthreshold hypomanic and depressive symptoms	Symptoms don’t meet full criteria for hypomania or MDD, but mood swings are chronic and impairing

Course, Triggers, and Risk Factors

Episodic Nature: Mood episodes may occur irregularly, with periods of remission in between. Stressful life events, seasonal changes, or sleep disruptions can trigger episodes.
Rapid Cycling: Defined as 4 or more mood episodes per year; more common in Bipolar II and is associated with poorer prognosis.
Kindling Hypothesis: Each episode increases the risk of future episodes by sensitizing the brain to mood dysregulation.

Biological and Psychological Correlates

Neurotransmitters:
- Increased dopaminergic and glutamatergic activity in mania
- Altered serotonin and norepinephrine levels across phases
Genetics:
- Strong heritability; first-degree relatives of patients with bipolar disorder have significantly higher risk
- Twin studies show concordance rates of ~70% for Bipolar I in monozygotic twins
Sleep-Wake Disturbance:
- Insomnia or irregular sleep patterns may both trigger and result from manic episodes
- Disrupted circadian rhythms are implicated in pathophysiology

Treatment Approaches

Pharmacotherapy:
- Mood Stabilizers:
  - Lithium: First-line maintenance treatment; reduces suicide risk; narrow therapeutic index requires monitoring
  - Anticonvulsants: e.g., valproate, lamotrigine, carbamazepine — useful for rapid cycling or mixed episodes
- Atypical Antipsychotics:
  - e.g., olanzapine, quetiapine, lurasidone — used during acute mania or as adjunct maintenance
Psychotherapy:
- Cognitive Behavioral Therapy (CBT): Assists with medication adherence and coping strategies
- Psychoeducation: Helps patients recognize early warning signs and triggers
- Interpersonal and Social Rhythm Therapy (IPSRT): Focuses on stabilizing daily routines and sleep-wake cycles
Lifestyle and Support:
- Regular sleep schedules, reduced substance use, and strong social support networks can enhance long-term stability

MCAT Considerations

Focus on diagnostic distinctions between Bipolar I, II, and Cyclothymia
Understand the role of neurotransmitters and genetic vulnerability
Be familiar with treatment modalities and the importance of medication adherence

Schizophrenia Spectrum and Other Psychotic Disorders

Schizophrenia spectrum disorders are characterized by distortions in thinking, perception, emotions, and behavior that result in impaired reality testing and social or occupational dysfunction. The MCAT focuses primarily on schizophrenia itself, though related conditions are relevant for understanding the full spectrum of psychosis.

Core Features of Psychotic Disorders

The DSM-5 defines the following core symptoms of psychosis:

Delusions: Fixed, false beliefs not grounded in reality (e.g., persecutory, grandiose, or referential).
Hallucinations: Perceptions without external stimuli, most commonly auditory (e.g., hearing voices).
Disorganized thinking (speech): Incoherence, derailment, loose associations.
Grossly disorganized or catatonic behavior: Inappropriate, bizarre movements or postures; extreme agitation or immobility.
Negative symptoms: Absence of normal function — e.g., flat affect, anhedonia, avolition, alogia, and social withdrawal.

MCAT Tip: Schizophrenia requires ≥2 symptoms for ≥6 months, with at least 1 being delusions, hallucinations, or disorganized speech.

Types of Symptoms

Symptom Type	Description	Examples
Positive Symptoms	Excesses or distortions of normal functioning	Delusions, hallucinations, disorganized speech
Negative Symptoms	Loss or diminution of normal functions	Flat affect, anhedonia, reduced speech or motivation
Cognitive Symptoms	Subtle deficits in executive function	Impaired attention, working memory, planning

Schizophrenia Diagnosis (DSM-5 Criteria)

Duration: Continuous signs of disturbance for ≥6 months, including ≥1 month of active-phase symptoms
Functional Impairment: Marked decline in work, interpersonal, or self-care functioning
Phases:
- Prodromal Phase: Gradual onset of subtle symptoms (e.g., social withdrawal, odd thinking)
- Active Phase: Full-blown psychotic features (delusions, hallucinations)
- Residual Phase: Some symptoms persist, especially negative and cognitive ones

Related Disorders on the Schizophrenia Spectrum

Disorder	Duration	Features	Notes
Brief Psychotic Disorder	<1 month	Sudden onset of psychotic symptoms (often in response to stress)	Full return to premorbid functioning
Schizophreniform Disorder	1–6 months	Meets schizophrenia criteria but does not persist ≥6 months	Often a precursor to schizophrenia
Schizoaffective Disorder	Mood episode + schizophrenia symptoms	Psychosis persists for ≥2 weeks without mood symptoms	Combines features of mood and psychotic disorders
Delusional Disorder	≥1 month	Non-bizarre, fixed delusions (e.g., being followed, poisoned) without hallucinations or disorganized behavior	Functioning usually preserved

Neurobiological Correlates of Schizophrenia

Dopamine Hypothesis: Overactivity of dopamine pathways (particularly mesolimbic) contributes to positive symptoms; underactivity in mesocortical pathways contributes to negative and cognitive symptoms.
Glutamate Hypothesis: NMDA receptor dysfunction may play a role in symptom development.
Brain Structure Abnormalities:
- Enlarged ventricles
- Decreased cortical volume (especially in prefrontal cortex)
- Disorganized hippocampal neurons
Genetics:
- Strong hereditary component (monozygotic twin concordance ~50%)
- Multiple susceptibility genes (e.g., COMT, DISC1)

Risk Factors and Prognostic Indicators

Prenatal insults: Maternal malnutrition, hypoxia, viral infection
Substance use: Cannabis use during adolescence increases risk
Course: Chronic, relapsing with variable outcomes; early intervention improves prognosis
Better prognosis associated with:
- Late onset
- Acute symptom onset
- Good premorbid function
- Strong social support
- Predominantly positive symptoms

Treatment Approaches

Category	Examples	Mechanism	Notes
Typical Antipsychotics	Haloperidol, chlorpromazine	Dopamine D2 receptor antagonists	Effective for positive symptoms, but higher risk of extrapyramidal side effects (EPS)
Atypical Antipsychotics	Risperidone, olanzapine, clozapine	D2 and serotonin (5-HT2A) antagonists	Lower EPS risk; treat positive and negative symptoms; clozapine reserved for treatment-resistant cases (risk of agranulocytosis)

Psychosocial Interventions:
- CBT for delusion management
- Social skills training
- Family therapy
Coordinated Specialty Care (CSC): Combines medication, therapy, employment support, and education for early-phase schizophrenia

MCAT Considerations

Know DSM-5 diagnostic criteria and phases of schizophrenia
Distinguish positive vs. negative symptoms
Understand dopamine and brain structure involvement
Be able to compare related psychotic disorders
Recognize that schizophrenia affects both biological and sociocultural domains

Trauma- and Stressor-Related Disorders

Trauma- and stressor-related disorders are characterized by psychological distress arising in response to exposure to a traumatic or highly stressful event. Unlike anxiety disorders, which may arise without a specific external trigger, these disorders are explicitly linked to identifiable stressors. The nature, duration, and severity of the trauma, as well as individual risk factors, influence symptom development and course.

Core Concepts

Trauma refers to exposure to actual or threatened death, serious injury, or sexual violence. This may occur through direct experience, witnessing it happen to others, or learning about it occurring to a close associate.
Stressors may include major life changes (e.g., divorce, job loss), natural disasters, combat, assault, or chronic adversity (e.g., childhood neglect).

MCAT Tip: These disorders differ from general anxiety or mood disorders in that the presence of a specific, identifiable event is central to diagnosis.

Post-Traumatic Stress Disorder (PTSD)

PTSD arises after a traumatic event and involves persistent symptoms that interfere with functioning for at least 1 month. The DSM-5 outlines four symptom clusters:

Symptom Cluster	Description	Examples
Intrusion	Recurrent, involuntary memories or dreams of the trauma	Flashbacks, nightmares
Avoidance	Efforts to avoid trauma-related thoughts, feelings, or reminders	Avoiding conversations, locations
Negative Cognitions and Mood	Persistent negative beliefs or emotional states	Guilt, detachment, hopelessness
Hyperarousal	Increased reactivity and vigilance	Exaggerated startle response, sleep disturbances, irritability

Risk Factors:

Pre-trauma: Prior mental illness, lack of social support
Peritrauma: Perceived threat to life, dissociation during trauma
Post-trauma: Poor coping mechanisms, ongoing stressors

Neurobiology:

Hyperactive amygdala → fear and threat perception
Hypoactive prefrontal cortex → impaired fear regulation
Reduced hippocampal volume → memory integration deficits
Dysregulated HPA axis → cortisol imbalance

Acute Stress Disorder (ASD)

ASD features similar symptoms to PTSD but occurs within 3 days to 1 month following trauma. It may progress to PTSD if symptoms persist.

Feature	PTSD	ASD
Onset	>1 month after trauma	3 days–1 month after trauma
Duration	≥1 month	<1 month
Symptoms	Same symptom clusters	Same, but duration is shorter
Progression	Chronic unless treated	May resolve or evolve into PTSD

Adjustment Disorders

These disorders involve emotional or behavioral symptoms in response to an identifiable non-traumatic stressor (e.g., breakup, job loss, relocation) that are out of proportion to the stressor and impair functioning.

Key Features:

Onset within 3 months of the stressor
Symptoms do not meet criteria for another mental disorder
Distress exceeds what would be expected for the context
Symptoms resolve within 6 months after stressor ends

MCAT Note: Adjustment disorder is not the same as grief or major depression. It is a stress-related reaction that is maladaptive but not severe enough to be classified as PTSD or another disorder.

Treatment Approaches

Disorder	First-Line Treatments	Additional Strategies
PTSD	Trauma-focused CBT, SSRIs (e.g., sertraline, paroxetine)	EMDR (eye movement desensitization), group therapy
ASD	Brief CBT, psychoeducation	Monitoring for progression
Adjustment Disorder	Supportive psychotherapy	Short-term anxiolytics if needed

Trauma-Focused CBT: Aims to desensitize individuals to traumatic memories, challenge cognitive distortions, and improve coping.
Pharmacologic Support:
- SSRIs: First-line for PTSD
- Prazosin: May reduce trauma-related nightmares
- Benzodiazepines: Generally avoided due to addiction potential and reduced efficacy

MCAT Considerations

Know diagnostic distinctions between PTSD, ASD, and Adjustment Disorder
Recognize the timing and symptom duration criteria
Understand how biological systems like the HPA axis contribute to trauma response
Be familiar with cognitive-behavioral interventions and pharmacologic options

Feeding and Eating Disorders

Feeding and eating disorders involve severe disturbances in eating behavior and related thoughts or emotions. These disorders can result in significant physical health consequences and are heavily influenced by psychological and sociocultural factors. The MCAT emphasizes the recognition of diagnostic criteria and distinctions among major eating disorders.

Anorexia Nervosa (AN)

Characterized by restriction of energy intake leading to significantly low body weight, intense fear of gaining weight, and distorted body image.

Subtypes:

Restricting Type: Weight loss is primarily through dieting, fasting, or excessive exercise
Binge-Eating/Purging Type: Regular episodes of binge eating or purging behaviors (e.g., vomiting, laxatives)

Clinical Features:

Underweight (BMI < 18.5 kg/m²)
Amenorrhea (loss of menstrual period — no longer required for diagnosis)
Denial of seriousness of low weight

Bulimia Nervosa (BN)

Recurrent episodes of binge eating followed by inappropriate compensatory behaviors (e.g., vomiting, laxatives, fasting, excessive exercise). Body weight is typically normal or slightly overweight.

Binge Episode Criteria:

Eating a larger amount of food than normal in a discrete time period
Sense of loss of control during the episode

Compensatory Behaviors:

Purging (e.g., vomiting, diuretics)
Non-purging (e.g., fasting, over-exercising)

Medical Complications:

Electrolyte imbalances (hypokalemia)
Esophageal tears
Parotid gland enlargement

Binge-Eating Disorder (BED)

Recurrent binge eating without compensatory behaviors. Associated with obesity, shame, and loss of control.

Key Differences from BN:

No purging
Often leads to weight gain and obesity-related health issues

MCAT Considerations

Differentiate between AN, BN, and BED by body weight and presence/absence of purging
Understand that BN can occur at normal weight
Know common complications: electrolyte imbalances, dental erosion, amenorrhea
Be aware of the role of distorted body image and societal pressures

Neurodevelopmental and Neurocognitive Disorders

This section covers two distinct clusters of disorders:

Neurodevelopmental Disorders, which typically manifest early in life and impair personal, social, academic, or occupational functioning.
Neurocognitive Disorders, which are acquired conditions that result in cognitive decline after a period of normal functioning, typically due to aging or brain damage.

Neurodevelopmental Disorders

Autism Spectrum Disorder (ASD)

A complex developmental condition characterized by persistent deficits in social communication and interaction, along with restricted, repetitive patterns of behavior, interests, or activities.

Core Domains:

Social-emotional reciprocity (e.g., difficulty with conversation, reduced sharing of emotions)
Nonverbal communicative behaviors (e.g., poor eye contact, atypical gestures)
Developing, maintaining, and understanding relationships

Repetitive Behaviors May Include:

Stereotyped movements (e.g., hand flapping)
Insistence on sameness or routines
Fixated interests
Hyper- or hypo-reactivity to sensory input

Additional Notes:

Symptoms must be present in early developmental period
Severity varies widely across individuals
Often comorbid with intellectual disability or language impairment

Attention-Deficit/Hyperactivity Disorder (ADHD)

Characterized by a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development.

Key Domains:

Inattention: Difficulty sustaining attention, disorganization, forgetfulness, distractibility
Hyperactivity-Impulsivity: Fidgeting, restlessness, interrupting, difficulty waiting turn

Diagnostic Criteria:

Several symptoms present before age 12
Present in two or more settings (e.g., school and home)
Interfere with functioning or development

Intellectual Disability (ID)

Formerly known as mental retardation, characterized by:

Deficits in intellectual functions (e.g., reasoning, problem-solving)
Deficits in adaptive functioning (e.g., communication, independent living)
Onset during the developmental period

Severity ranges from mild to profound.

Specific Learning Disorders

Difficulties learning and using academic skills, despite appropriate educational interventions.

Common areas: reading (dyslexia), mathematics (dyscalculia), writing (dysgraphia)

Neurocognitive Disorders

These disorders represent a decline from a previous level of performance in one or more cognitive domains.

Delirium

An acute, reversible disturbance in attention and cognition that develops over a short period of time (usually hours to days).

Key Features:

Fluctuating consciousness and alertness
Disorganized thinking and speech
Reversible and often caused by a medical condition (e.g., infection, substance withdrawal)

Major Neurocognitive Disorder (Dementia)

A progressive and irreversible decline in cognitive function, affecting memory, language, executive function, or other domains.

Common Causes:

Alzheimer’s disease: Most common; associated with beta-amyloid plaques and tau tangles
Vascular dementia: Multiple strokes cause stepwise decline
Lewy body dementia: Visual hallucinations, Parkinsonian features

MCAT Note:

Know the difference between delirium (acute, reversible) and dementia (chronic, progressive)
Recognize features of Alzheimer’s, vascular dementia, and Lewy body dementia

MCAT Considerations

Differentiate developmental vs. acquired disorders
Understand diagnostic features of ASD and ADHD
Distinguish between delirium and dementia (onset, course, reversibility)
Know hallmark features of Alzheimer’s and related dementias

Somatic Symptom and Related Disorders

Somatic symptom and related disorders are characterized by physical symptoms that suggest a medical condition but are not fully explained by a general medical disorder, substance use, or another mental disorder. These conditions involve a prominent focus on somatic (bodily) concerns that cause significant distress or impairment.

1. Somatic Symptom Disorder

One or more somatic symptoms that are distressing or result in significant disruption of daily life
Excessive thoughts, feelings, or behaviors related to the symptoms or associated health concerns
Symptoms may or may not have a medical explanation
MCAT Tip: Emphasis is on psychological response to the symptoms, not the presence or absence of a medical condition

2. Illness Anxiety Disorder (formerly Hypochondriasis)

Preoccupation with having or acquiring a serious illness
Somatic symptoms are not present or are mild
High level of anxiety about health; frequent health-related behaviors or avoidance
Symptoms persist for at least 6 months
Often misinterprets normal sensations (e.g., heartbeat, sweating) as signs of serious illness

3. Conversion Disorder (Functional Neurological Symptom Disorder)

Neurological symptoms (e.g., paralysis, blindness, seizures) incompatible with recognized medical conditions
Often associated with psychological stress or trauma
Symptoms are not intentionally produced
May present with “la belle indifférence” — an inappropriate lack of concern about the symptoms

4. Factitious Disorder

Falsification of physical or psychological symptoms, or induction of injury or disease, associated with deception
The individual presents themselves (or another, in the case of Factitious Disorder Imposed on Another) as ill, impaired, or injured
The behavior is evident even in the absence of obvious external rewards (distinguishing it from malingering)

MCAT Considerations

Differentiate between disorders based on intent and symptom source:
- Somatic Symptom Disorder: Real symptoms, excessive psychological response
- Illness Anxiety Disorder: Minimal/no symptoms, health preoccupation
- Conversion Disorder: Neurological-like symptoms with no physiological cause
- Factitious Disorder: Intentional deception without external gain
Understand the role of psychological distress in somatic symptom disorders
Recognize overlap with anxiety and depressive disorders

Disruptive, Impulse-Control, and Conduct Disorders

These disorders involve problems with emotional and behavioral self-control, manifesting as socially unacceptable, aggressive, or defiant behaviors. They typically arise in childhood or adolescence and can persist into adulthood if untreated.

1. Oppositional Defiant Disorder (ODD)

A pattern of angry/irritable mood, argumentative/defiant behavior, or vindictiveness lasting at least 6 months
Symptoms are directed toward authority figures (e.g., parents, teachers)
Behavior is deliberate and defiant but does not include aggression or serious violations of social norms
MCAT Tip: Know that ODD can be a precursor to conduct disorder but is less severe

2. Conduct Disorder (CD)

Repetitive and persistent pattern of behavior that violates the rights of others or major age-appropriate norms
Behaviors include aggression to people and animals, destruction of property, deceitfulness or theft, and serious rule violations
Often associated with a lack of empathy and remorse
Onset typically before age 15; may progress to antisocial personality disorder in adulthood

3. Intermittent Explosive Disorder (IED)

Recurrent behavioral outbursts representing a failure to control aggressive impulses
Outbursts are grossly out of proportion to the provocation
Not premeditated or committed to achieve tangible objectives (e.g., money, power)
MCAT Tip: Distinguish from CD by the impulsivity and lack of persistent pattern

4. Pyromania

Deliberate and purposeful fire-setting on more than one occasion
Fascination with fire and its consequences
Tension or arousal before the act; relief or gratification after

5. Kleptomania

Recurrent failure to resist impulses to steal items not needed for personal use or monetary value
Tension before theft; pleasure or relief during the act
Items are often discarded or hoarded

MCAT Considerations

Focus on diagnostic features and behavioral patterns
Understand the role of impulse control and emotional regulation
Recognize developmental progression (e.g., ODD → CD → antisocial traits)
Be familiar with the distinction between impulsive vs. premeditated behaviors

Personality Disorders

Personality disorders are enduring patterns of inner experience and behavior that deviate markedly from cultural expectations, are pervasive and inflexible, and lead to distress or impairment. These patterns begin in adolescence or early adulthood and are stable over time.

The DSM-5 clusters personality disorders into three groups:

Cluster A – Odd or Eccentric

Disorder	Key Features	MCAT Notes
Paranoid PD	Distrust and suspiciousness of others	Often interprets benign remarks as threatening
Schizoid PD	Detachment from social relationships and limited emotional expression	Prefers solitary activities, indifferent to praise or criticism
Schizotypal PD	Acute discomfort in close relationships, cognitive/perceptual distortions, and eccentric behaviors	Odd beliefs, magical thinking, unusual speech

Cluster B – Dramatic, Emotional, or Erratic

Disorder	Key Features	MCAT Notes
Antisocial PD	Disregard for and violation of others’ rights	Must be 18+ with conduct disorder history before age 15
Borderline PD	Instability in relationships, self-image, and emotions	Fear of abandonment, impulsivity, self-harm
Histrionic PD	Excessive emotionality and attention-seeking	Easily influenced, theatrical behavior
Narcissistic PD	Grandiosity, need for admiration, and lack of empathy	Fragile self-esteem underneath exaggerated self-importance

Cluster C – Anxious or Fearful

Disorder	Key Features	MCAT Notes
Avoidant PD	Social inhibition, feelings of inadequacy, hypersensitivity to negative evaluation	Desires relationships but avoids due to fear of rejection
Dependent PD	Excessive need to be taken care of, leading to submissive and clinging behavior	Difficulty making decisions without reassurance
Obsessive-Compulsive PD	Preoccupation with orderliness, perfectionism, and control	Different from OCD; ego-syntonic (behaviors align with self-image)

MCAT Considerations

Focus on differentiating personality disorders based on symptom clusters
Know the difference between OCD and OCPD
Understand how these disorders impact functioning and relationships
Recognize that Cluster B (especially antisocial and borderline) often appear in clinical case scenarios

Substance-Related and Addictive Disorders

These disorders are characterized by the compulsive use of substances or engagement in behaviors despite harmful consequences. The brain’s reward system, particularly dopaminergic pathways, plays a central role in addiction.

Core Diagnostic Features

Impaired control over use (e.g., using more than intended, unsuccessful attempts to quit)
Social impairment (e.g., failure to fulfill roles, strained relationships)
Risky use (e.g., use in hazardous situations)
Pharmacological criteria (tolerance and withdrawal)

Major Categories

Category	Description	Examples
Substance Use Disorders	Problematic use of a drug or alcohol leading to impairment/distress	Alcohol, opioids, stimulants, sedatives, cannabis
Substance-Induced Disorders	Symptoms directly caused by substance intoxication or withdrawal	Substance-induced psychosis, depression
Behavioral Addictions	Compulsive engagement in non-substance behaviors with addictive features	Gambling disorder (officially recognized); internet/gaming disorders under study

Neurobiology of Addiction

Dopamine Pathways: Particularly the mesolimbic pathway (ventral tegmental area → nucleus accumbens)
Reward Sensitization: Repeated use leads to greater salience of drug-related cues
Tolerance: More of the substance is needed to achieve the same effect
Withdrawal: Physiological symptoms upon cessation (e.g., tremors, anxiety, nausea)

Risk Factors

Genetic predisposition
Early exposure to substances
Mental health comorbidities (e.g., depression, ADHD)
Trauma and environmental stressors

Treatment Approaches

Behavioral Therapies: Cognitive behavioral therapy (CBT), contingency management, motivational interviewing
Pharmacological Interventions:
- Methadone, buprenorphine (opioid use disorder)
- Naltrexone (opioids and alcohol)
- Disulfiram (alcohol)
12-Step Programs: Alcoholics Anonymous (AA), Narcotics Anonymous (NA)

MCAT Considerations

Focus on the diagnostic features and categories of substance-related disorders
Know the reward pathway and its relation to addiction
Understand the roles of tolerance and withdrawal
Be familiar with major treatment strategies