mental illness

Introduction to Mental Illness Neurobiology

  • Mental illnesses

    • Happen to people from all cultures and income levels

    • Show many different symptoms, which can be mild or severe

  • Symptoms are a sign of:

    • Problems with how the brain is built and how it works

    • How a person's genes and environment affect each other

  • While genes can make someone more likely to get a mental illness, they don't cause it alone; environmental factors (like stress or experiences) can start or worsen the symptoms.

  • Brain scans (neuroimaging) reveal physical and functional changes in the brain linked to mental disorders.

  • Understanding how the brain works in these illnesses helps us:

    • Create specific treatments

    • Improve how well patients get better

Schizophrenia Overview

  • How common it is

    • Affects about 1 out of every 100 people worldwide

    • Usually starts in the late teenage years to early adulthood

    • Males often show symptoms earlier than females

    • Symptoms typically appear when a person is in their late teens to early twenties

  • Common symptoms include:

    • Hallucinations: Seeing, hearing (most common), or feeling things that aren't there

    • Delusions: Strong, false beliefs that aren't based in reality (e.g., paranoia, believing you have special powers)

    • Disorganized speech (trouble putting thoughts into clear sentences)

    • Unusual or strange behaviors

  • Symptoms are grouped into:

    • Positive symptoms:

    • These are added experiences or distortions of normal functions; they often make a person lose touch with reality

    • Negative symptoms:

    • Reduced emotional expression, loss of pleasure (anhedonia), lack of motivation (avolition), pulling away from social interactions

    • Cognitive deficits (thinking problems):

    • Affect attention, memory, and problem-solving abilities, which severely impact daily life and the ability to reach goals

Genetic and Environmental Factors in Schizophrenia

  • Schizophrenia tends to run in families (is highly heritable), but it's not caused by a single gene:

    • If one identical twin has it, the other twin has a 30%-50% chance of developing it

    • Fraternal twins and siblings have about a 12% chance, which is higher than the general population's 1% risk

    • Many different genes (like DISC1, neuroregulin 1) are linked to the disorder, but they don't fully explain it

    • Having these risk genes doesn't mean you will definitely get the illness

  • Environmental factors occurring before or around birth can change the risk of schizophrenia:

    • Infections or lack of nutrients during pregnancy can disrupt normal brain development

    • Problems during or right after birth (e.g., birth defects, lack of oxygen to the brain) increase vulnerability

    • Growing up in a city is linked to a higher chance of schizophrenia, possibly due to stress or environmental exposures

    • How genes and environment interact affects when and how severely brain structure and function are disrupted

Brain Abnormalities in Schizophrenia

  • Enlarged Ventricles

    • MRI scans consistently show that the fluid-filled spaces (lateral and third cerebral ventricles) in the brain are larger than normal

    • This is linked to thinking difficulties and negative symptoms

  • Smaller Hippocampus

    • People with schizophrenia often have a smaller hippocampus, a brain area important for memory

  • Prefrontal Cortex Changes

    • A gradual loss of gray matter occurs in the dorsolateral prefrontal cortex, the part of the brain involved in planning and decision-making

    • This reduces blood flow and brain activity in this area, making it harder to remember things short-term (working memory) and to focus on goals in schizophrenia

Neurotransmitter Alterations in Schizophrenia

  • The Dopamine Hypothesis

    • Schizophrenia is thought to be linked to unusual dopamine activity in certain brain pathways

    • High dopamine levels in the mesolimbic pathway are connected to positive symptoms (like hallucinations and delusions)

    • Low dopamine levels in the mesocortical pathway are linked to negative and cognitive symptoms

    • Older antipsychotic medicines block dopamine D2 receptors, which helps reduce positive symptoms

    • Both too much and too little dopamine activity in different brain areas help explain the variety of symptoms seen in schizophrenia

  • Glutamate and NMDA Receptors

    • Glutamate, a key excitatory neurotransmitter (brain chemical that speeds up signals), is also involved in schizophrenia

    • Underactivity of NMDA glutamate receptors contributes to symptoms

    • Lower glutamate levels are found in the fluid around the brain and spinal cord, and less is produced in the brain

    • Drugs like PCP that block NMDA receptors can cause schizophrenia-like symptoms

    • Problems with glutamate affect thinking and negative symptoms, adding to the dopamine theory

Clinical Manifestations of Schizophrenia

  • Hallucinations:

    • Examples: hearing voices, seeing things that aren't there

  • Delusions:

    • Examples: extreme suspicion (paranoia), believing one is very important (grandiosity)

    • For instance, a patient might hear voices talking about their actions or believe their thoughts are being controlled by an outside force

  • Difficulties with emotions and behavior:

    • Showing little emotion (flattened affect), inability to feel pleasure (lack of pleasure), speaking less, and having low motivation

    • These lead to social isolation and make daily life challenging

  • Problems with attention, short-term memory, and executive functions (like planning)

    • Patients find it hard to plan, make decisions, and understand information, which interferes with routine tasks and social interactions

    • Example: a patient might react with happiness when talking about a sad event

    • Difficulty completing everyday tasks due to lack of drive

Treatment of Schizophrenia

  • Antipsychotic Medications

    • First-generation antipsychotics block dopamine D2 receptors to reduce positive symptoms:

    • Examples: chlorpromazine, haloperidol, and fluphenazine

    • Side effects include problems with movement (like Parkinson's disease), involuntary movements (tardive dyskinesia), sleepiness, and weight gain

    • Second-generation antipsychotics target both dopamine and serotonin receptors, which can help with negative symptoms:

    • Examples: clozapine, risperidone, olanzapine, quetiapine; these often have metabolic side effects (e.g., weight gain, changes in blood sugar)

  • Role of Psychotherapy

    • Psychosocial therapies help patients learn coping skills and stick to their medication schedule

    • Cognitive-behavioral therapy (CBT) helps patients change how they think about delusions and hallucinations

    • Family support helps reduce the chances of symptoms returning and improves social functioning

    • Psychotherapy works best with medication for managing all symptoms

Mood Disorders: Depression and Bipolar Disorder

  • Mood disorders involve long-lasting emotional states that significantly affect daily life:

    • Unipolar depression: ongoing sadness

    • Bipolar disorder: periods of extreme energy and high mood (mania) alternating with periods of depression

  • Symptoms can include:

    • Feeling sad or irritable

    • Losing interest or pleasure in activities

    • Significant changes in weight

    • Trouble sleeping (too much or too little)

    • Changes in movement (either very slow or very agitated)

    • Feeling tired all the time

    • Feelings of worthlessness or guilt

    • Trouble focusing

    • Repeated thoughts of death or suicide

  • Bipolar disorder includes episodes of mania, which involve:

    • Feeling overly happy or energetic

    • Increased energy levels

    • Needing less sleep

    • Talking very fast

    • Easily distracted

    • Engaging in risky behaviors

  • Diagnosis requires:

    • Mood episodes lasting for specific amounts of time

    • Meeting specific symptom criteria as outlined in the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders)

Genetic and Environmental Influences in Mood Disorders

  • Genetic Predisposition

    • Studies on families and twins show that mood disorders are often inherited:

    • For bipolar disorder, if one identical twin has it, the other has up to a 62% chance

    • For unipolar depression, this is about 42%

    • Multiple genes are involved, with specific gene locations on chromosomes 18 and 22 linked to both bipolar disorder and schizophrenia

    • Genetic factors impact brain chemical systems (like serotonin and dopamine) that regulate mood

    • There's a genetic overlap between mood disorders and other mental health conditions, suggesting similarities in their biological causes

  • Environmental Triggers and Neurochemical Dysregulation

    • Stressful life events can trigger mood episodes in people who are genetically vulnerable

    • Problems with monoamine neurotransmitters (norepinephrine, dopamine, serotonin) are key to both depression and mania

    • Long-term stress increases cortisol (a stress hormone), which then increases pro-inflammatory cytokines (immune chemicals) that worsen depressive symptoms

    • Hormone imbalances, including issues with the HPA axis (brain-hormone system) and thyroid hormones, also play a role in mood disorders

Neuroendocrine Dysregulation in Depression

  • HPA Axis and Stress Response

    • The hypothalamic-pituitary-adrenal (HPA) axis controls the body's response to stress by managing the release of cortisol

    • Ongoing stress causes the HPA axis to be overly active, leading to high levels of cortisol

  • Impact on Brain and Symptoms

    • High cortisol levels disrupt brain function and make depressive symptoms worse; this disruption is a key part of the neurobiology of depression

  • Immune Activation and Inflammation

    • Stress increases pro-inflammatory cytokines (e.g., IL-1, IL-6, TNF-alpha), which activate the HPA axis and change how neurotransmitters are processed

    • High levels of these inflammation markers are linked to a greater risk of depression

  • Role of Omega-3 Fatty Acids

    • Omega-3 fatty acids (EPA and DHA) might help reduce inflammation and depressive symptoms

    • This highlights how brain-hormone systems and the immune system interact in depression

Brain Structure and Function in Mood Disorders

  • Brain imaging studies show:

    • Reduced blood flow and glucose (sugar) use in the dorsolateral and dorsomedial prefrontal cortex (brain areas for thinking and emotional control)

    • This impairs how people think and manage their emotions

  • Amygdala Changes

    • The amygdala (brain area for emotions) often changes in size: it can be larger in early depression and smaller after repeated episodes

    • These changes are linked to stronger emotional responses and anxiety

  • Reduced size of the hippocampus (memory center) and imbalances in neurotransmitters (like serotonin, norepinephrine, glutamate) contribute to:

    • Memory problems

    • Difficulty controlling mood

    • Reduced growth of new brain cells in depression

Treatment of Depression and Bipolar Disorder

  • Antidepressants

    • These include MAOIs, TCAs, SSRIs, and atypical drugs that increase monoamine neurotransmitters (brain chemicals like serotonin, norepinephrine, and dopamine)

    • SSRIs are usually the first choice because they work well and have fewer side effects

    • Side effects vary by drug type and need to be monitored

  • Lithium as a treatment for bipolar disorder

    • It is still considered the best treatment and is often used with anticonvulsants (anti-seizure drugs) and second-generation antipsychotics

    • Effective in managing manic and depressive episodes and preventing them from returning

  • Electroconvulsive Therapy (ECT)

    • Highly effective for severe depression and mania that haven't responded to other treatments

    • Can quickly relieve symptoms and even increase the size of the hippocampus

    • Requires anesthesia and careful selection of patients

  • Other Emerging Treatments

    • Deep brain stimulation (DBS) and transcranial magnetic stimulation (TMS) are options for cases that don't respond to standard treatments

    • Esketamine nasal spray offers fast antidepressant effects for difficult-to-treat depression; its long-term safety is still being studied

Anxiety Disorders Overview

  • These disorders are characterized by sudden, intense panic attacks with symptoms such as:

    • Fast heartbeat

    • Sweating

    • Fear of losing control

  • Often accompanied by agoraphobia:

    • Fear of places or situations from which escape might be difficult or embarrassing

  • Social Anxiety Disorder:

    • Marked by extreme fear and avoidance of social situations due to worry about being judged negatively or embarrassed

  • Generalized Anxiety Disorder (GAD):

    • Involves persistent and excessive worry about many different things for at least 6 months

    • Symptoms include restlessness, muscle tension, irritability, and difficulty concentrating

    • Symptoms can change over time and often occur alongside depression

Panic Disorder: Pathophysiology and Treatment

  • How it works (Pathophysiology)

    • Involves sudden panic attacks with strong physical symptoms like a fast heart rate and sweating

    • Patients are very sensitive to changes in brain pH (acidity), especially in the amygdala, a fear-processing area

    • Chemicals like carbon dioxide and sodium lactate can trigger panic symptoms by changing brain pH

    • The locus ceruleus (brain area for alertness) and its norepinephrine system increase physical arousal, making panic worse

    • Reduced binding of benzodiazepine receptors in the hippocampus and prefrontal cortex contributes to panic and anxiety symptoms

  • Treatment Options

    • Cognitive-behavioral therapy (CBT) helps patients manage anxiety and understand their panic symptoms

    • First-line medications include:

    • SSRIs like paroxetine and sertraline

    • SNRIs such as venlafaxine

    • Benzodiazepines (e.g., alprazolam) are used short-term or as add-ons for people who don't respond to SSRIs

    • Breathing exercises in CBT help reduce over-breathing and physical symptoms during attacks

    • Slowly stopping benzodiazepines while doing CBT helps reduce dependence and the risk of relapse

Social Anxiety Disorder: Neurobiology and Treatment

  • Brain Abnormalities in SAD

    • Increased activity in the amygdala (fear center) when a person perceives social threats

    • Reduced communication between the amygdala and the prefrontal cortex (for emotional control), which impairs emotional regulation

    • Lower binding of serotonin 5-HT1A receptors in the amygdala and related areas

    • Lower levels of GABA (a calming brain chemical) in the thalamus contribute to increased anxiety

    • Reduced oxytocin (a bonding hormone) levels affect social bonding and reduce fear

  • Treatment Strategies

    • SSRIs (e.g., fluoxetine, paroxetine) reduce an overactive amygdala and anxiety symptoms

    • Cognitive-behavioral therapy (CBT) helps patients change negative thoughts about social situations and improve coping skills

    • Intranasal oxytocin (nose spray) shows promise in reducing amygdala reactions and improving social interaction

    • Medication side effects can include agitation and sexual problems, requiring careful management

    • Combining therapy and medication often leads to better long-term results

Generalized Anxiety Disorder: Features and Treatment

  • Core Features and Neurobiology

    • Persistent, excessive worry about many different life events for at least 6 months

    • Symptoms include:

    • Restlessness

    • Muscle tension

    • Irritability

    • Fatigue

    • Sleep problems

    • Increased activity in the cingulate cortex (brain area for emotion and decision-making) linked to worrying about future events

    • Heightened amygdala activation (fear center) correlates with being overly alert to threats

    • Reduced serotonin and norepinephrine receptor binding has been observed

  • Treatment Approaches

    • SSRIs and SNRIs are the usual first medications prescribed

    • Buspirone affects serotonin receptors but takes longer to start working

    • Benzodiazepines are used for short periods only due to risks of dependence

    • Cognitive-behavioral therapy teaches relaxation and coping skills

    • Combination therapy often improves symptom control and quality of life

Posttraumatic Stress Disorder (PTSD)

  • Definition

    • Develops after a person experiences a life-threatening or traumatic event

  • Symptoms include:

    • Flashbacks (reliving the event)

    • Nightmares

    • Avoiding reminders of the trauma

    • Negative changes in mood

    • Being constantly on edge (hyperarousal) that disrupt daily life

  • Key brain areas affected include:

    • Amygdala: leads to a stronger fear response

    • Prefrontal cortex: reduces its ability to control fear

    • Hippocampus: a smaller volume affects memory and how emotions are processed

  • Treatment Approaches

    • First-line treatments:

    • SSRIs: paroxetine, sertraline

    • Psychotherapy: including exposure therapy (gradually confronting trauma memories)

    • Newer treatments like esketamine show promise for cases that don't respond to other treatments

Emerging Treatments for PTSD

  • Repeated intravenous ketamine infusions can quickly reduce PTSD symptoms within 24 hours

  • Ketamine helps reduce intrusive thoughts, avoidance, and negative mood changes associated with PTSD

  • Esketamine: a nasal spray approved for treatment-resistant depression is being studied for its potential to treat PTSD

  • Both treatments target NMDA glutamate receptors (a specific type of brain chemical receptor), offering a new way to treat the disorder that is different from traditional SSRIs

  • The long-term safety and effectiveness of ketamine and esketamine for PTSD are still being researched through ongoing clinical trials

Obsessive-Compulsive Disorder (OCD): Overview

  • Symptoms and Impact

    • Obsessions: unwanted, repeating thoughts that cause intense anxiety

    • Compulsions: repetitive behaviors or mental acts performed to reduce anxiety caused by obsessions

    • Common compulsions include washing, checking, counting, and organizing

    • OCD significantly harms:

    • Social relationships

    • Job performance

    • Academic success

    • Symptoms take up a lot of time, cause severe distress, and limit daily functioning

  • How common it is and related conditions

    • About 2% to 3% of people will have OCD at some point in their lives

    • It often starts in childhood or adolescence; it's slightly more common in males

    • Many people with OCD also have other disorders (e.g., major depression, panic disorder, generalized anxiety disorder)

    • In children: other common conditions include Tourette syndrome, ADHD, oppositional defiant disorder, and depression

    • About 30%-50% of adults with OCD say their symptoms started in childhood

OCD Neurobiology and Brain Circuits

  • Role of Basal Ganglia and Anterior Thalamus

    • Increased activity in parts of the basal ganglia (caudate, putamen) and the anterior thalamus (brain areas involved in movement and habit formation) contributes to the repetitive behaviors and compulsions seen in OCD

  • Involvement of Cingulate Cortex and Orbitofrontal Cortex

    • Overactivity in the dorsal anterior cingulate cortex and orbitofrontal cortex (brain areas for decision-making and emotion) disrupts cognitive control and emotional regulation

    • This reinforces obsessive thoughts and compulsive actions in people with OCD

Treatment of OCD

  • Pharmacologic Treatments (Medications)

    • SSRIs (e.g., fluoxetine, fluvoxamine, paroxetine, escitalopram, sertraline) are the first-choice drugs; 70%-80% of patients show some improvement

    • Clomipramine is used if SSRIs don't work

    • Benzodiazepines like clonazepam may be added to enhance therapy

  • Psychotherapeutic Approaches (Therapy)

    • CBT with exposure and response prevention involves exposing patients to things that trigger their anxiety while preventing them from performing their rituals

    • This reduces compulsions and improves long-term results

  • Advanced Treatments

    • For severe OCD, options include:

    • ECT (Electroconvulsive Therapy)

    • TMS (Transcranial Magnetic Stimulation)

    • DBS (Deep Brain Stimulation)

    • Neurosurgery (e.g., dorsal anterior cingulotomy) to target specific brain circuits to relieve symptoms when standard treatments fail

Summary of Key Points

  • Schizophrenia:

    • Involves positive symptoms (like hallucinations and delusions), negative symptoms (like lack of emotion and motivation), thinking problems, and changes in brain structure (enlarged ventricles, problems with the prefrontal cortex)

  • PTSD:

    • Involves problems in brain circuits that process fear (amygdala, prefrontal cortex); treatment challenges are addressed by therapy and SSRIs, with options like esketamine for some cases

  • Mood Disorders:

    • Include major depression and bipolar disorder, caused by imbalances in monoamine neurotransmitters, HPA axis problems, and structural changes in emotional and thinking brain areas; treatments range from antidepressants to advanced brain stimulation

  • Obsessive-Compulsive Disorder:

    • Characterized by dysfunctional basal ganglia and cingulate cortex circuits; treatments include SSRIs, CBT, and for difficult cases, DBS or brain surgery

  • Anxiety Disorders:

    • Include panic disorder, social anxiety disorder, and generalized anxiety disorder, involving an overactive amygdala and neurotransmitter imbalances; treated with CBT and SSRIs

Key Neurobiological Themes Across Disorders

  • Common themes include:

    • Imbalances in brain chemicals (neurotransmitters)

    • Physical changes in brain structures

    • The need for treatment plans that use multiple approaches, specifically designed for a person's unique symptoms

Real-Life Clinical Questions

  • A 22-year-old patient comes in hearing voices and pulling away from social interactions; what specific signs help confirm a diagnosis of schizophrenia?

  • How can you tell the difference between bipolar I and bipolar II disorder based on the types of mood episodes they experience?

  • What brain and chemical factors should guide treatment choices for major depressive disorder when a patient has high cortisol levels?

  • In panic disorder, how does being very sensitive to brain pH changes affect symptoms, and what are the initial treatments given?

  • What advanced treatments are available for OCD that hasn't responded to SSRIs and CBT, and how do they work in the brain?

Neurobiology's Role in Mental Health Treatment

  • Understanding how psychiatric disorders affect the brain is crucial for developing better treatments and improving patient outcomes.

  • Knowledge of genetics, brain chemistry, and structure helps tailor care for each person and supports the development of new therapies, improving the quality of life for those with mental illnesses.

Key Neurobiological Themes Across Disorders

  • Common themes include:

    • Neurotransmitter imbalances

    • Structural brain changes

    • Need for multimodal treatment strategies tailored to specific symptom clusters

Real-Life Clinical Questions

  • A 22-year-old patient presents with auditory hallucinations and social withdrawal; what are the key diagnostic criteria to confirm schizophrenia?

  • How to differentiate between bipolar I and bipolar II disorder based on mood episode characteristics?

  • What neurobiological factors influence treatment choices for major depressive disorder with elevated cortisol?

  • In panic disorder, how does heightened brain pH sensitivity affect symptoms and what are first-line treatments?

  • What advanced therapies are available for treatment-resistant OCD beyond SSRIs and CBT, and what is their neurobiological basis?

Neurobiology's Role in Mental Health Treatment

  • Understanding the neurobiology of psychiatric disorders is essential for advancing effective treatments and improving patient outcomes.

  • Knowledge of genetics, brain chemistry, and structure guides personalized care and supports new therapies, improving quality of life for those with mental illness.