Psychological Disorders

  • Mental Disorders
    • Major public health problem, affects the higher functions of the brain including cognition, mood, and behaviour.
    • Biomedical biopsychosocial models.
      • Bio = biological, physical abnormalities.
      • Psychosocial = psychological and cultural/social factors.
    • Difficult to categorize mental disorders
    • 2 classification systems: ICD-10 and DSM-5
      • ICD-10 is International Classification of Diseases, 10th System from the WHO.
      • DSM-5 is Diagnostic and Statistical Manual of Mental Disorders, 5th edition, from the American Psychiatric Association (APA).
    • According to the National Institute of Health (NIH), each year in the USA about 25% will meet criteria for 1 mental disorder, and 6% will have a serious mental illness that cause severe disability/distress.
  • Categories of Mental Disorders
    • Types of mental disorders – enormous #, many with overlapping features.
    • Not due to use of medication, drugs, other medical conditions, etc. Also cultural differences.
    • Usually causes distress/disability. Key point because person who’s unusual/eccentric does not have psychological disorder.
    • We’ll go through DSM-5
  • 20 top-level categories
  1. Neurodevelopmental Disorders – involve distress/disability due to abnormality in development of nervous system. Includes intellectual disability, autism spectrum disorders, and ADHD.
  2. Neurocognitive Disorders – Loss of cognitive/other functions of the brain after nervous system has developed. Big categories within this, one is delirium (reversible episode of cognitive/higher brain problems, many causes – drugs/blood/infections). Dementia and its milder versions are usually irreversible and progressive.
  3. Sleep-wake Disorders result in distress/disability from sleep-related issues. Include insomnia and breathing-related sleep disorders.
  4. 4. Anxiety Disorders – abnormal worry/fear. Some are specific to certain stimuli like phobias, while others are not specific to certain stimuli, including generalized anxiety disorder. Panic disorder involves panic attacks.
  5. Depressive Disorders – abnormally negative mood. Mood refers to long-term emotional state. Mood is also subjective experience person has of their experience. High risk of suicide.
  6. Bipolar and Related Disorders – abnormal mood, but these may have periods of abnormally positive mood called mania. Leads to social/legal problems.
  7. Schizophrenia Spectrum and other Psychotic Disorders – involves distress/disability from psychosis. Psychosis involves delusions (not explainable by experiences/culture), hallucinations.
  8. Trauma/Stressor-Related Disorders – occurs after stressful/traumatic events. Post-traumatic stress disorder, common after wars.
  9. Substance-Related and Addictive Disorders – distress/disability form use of substances that affect mental function. Include alcohol, caffeine, cannabis, hallucinogens, opioids, etc.
  10. Personality Disorders – related to personality. Involves long-term mental and behavioural features characteristic of a person, huge spectrum of personality types considered acceptable. Personality disorders involve ones outside those accepted of societal norms.
    • Cluster A odd/eccentric,
    • Cluster B intense emotional/relationship problems,
    • Cluster C is anxious/avoidant/obsessive
  11. Disruptive, Impulse-Control, and Conduct Disorders – inability to control inappropriate behaviours
  12. Obsessive-Compulsive and Related Disorders – compulsions are unwelcome thoughts that occur repeatedly. Ex. obsession with hands being dirty, compulsion to wash them many times a day.
  13. Somatic Symptom and Related Disorders – Distress/disability from symptoms similar to those that may occur to illness unrelated to mental disorder, but of psychological origin. Example is someone that has abdominal pain, caused by stress.
  14. Feeding and Eating Disorders – behavioural abnormalities related to food, ex. anorexia, bulimia.
  15. Elimination Disorders – urination/defecation at inappropriate times.
  16. Dissociative Disorders – abnormalities of identity/memory. Multiple personalities, or lost memories for part of their lives.
  17. Sexual Dysfunctions – abnormalities in performance of sexual activity.
  18. Gender Dysphoria – caused by person identifying as a different gender
  19. Paraphilic Disorders – having sexual arousal to unusual stimuli
  20. Other Disorders – any person that appears to have a mental disorder causing distress/disability but doesn’t fit into other categories. Rare.
  • Biological Basis of Schizophrenia
    • Prototype of psychotic category of disorders. Rare disorder with both biological and environmental etiology.
    • Abnormal perceptions of reality – hallucinations, delusions.
    • 3 categories of symptoms:
      • cognitive (attention, organization, planning abilities),
      • negative (blunted emotions),
      • positive (hallucinations, delusions)
    • Our understanding of the cause is very limited.
      • Cerebral cortex seems to have decreased size, in frontal and temporal lobes.
      • Some features of schizophrenia also involve abnormalities in dopamine (increase); medications affect dopamine transmission often improve symptoms
      • The mesocorticolimbic Meso = VTA in the midbrain, cortico = cortical cortex, they project to frontal and temporal lobe, and limbic – inside of brain involved in emotions/motivations/etc. Abnormal activity here. One way of thinking about schizophrenia is abnormal activity is:
        • Mesocorticolimbic pathway leads to dysfunction in parts of frontal cortex that cause cognitive symptoms
        • limbic structure causes negative symptoms
        • temporal cortex causes positive symptoms.
      • Causes: genes, physical stress during pregnancy, and psychosocial factors (negative family interaction styles affect development of brain).
      • Biological Basis of Depression
        • Feelings of hopelessness, loss of interest in activities. Our understanding of cause is limited. No consistent abnormalities in brain tissues, but scans have suggested functional abnormalities.
          • Areas with abnormal activity involve the frontal lobe and limbic structures. Decreased activity in frontal lobe and increased activity in limbic lobe.
          • Stress hormones like cortisol are controlled by the hypothalamus, which communicates with limbic and frontal lobe. Hormones affect the brain themselves too.
        • Abnormal pathways in depression.
          • One starts in the raphe nuclei of the brainstem responsible for serotonin
          • Also the locus coeruleus, which sends long axons to cerebrum and releases
          • Also the VTA sends long axons to different areas of cerebrum, supplies dopamine.
        • Medications that affect serotonin, NE, and dopamine often improve symptoms. Ex. monoamine oxidase inhibitors (increase amount of monoamines in synapse)
          • Monoamines include adrenaline, norepinephrine, dopamine, serotonin, and melatonin (involved in onset of darkness).
        • Another newer idea is may be abnormalities of neural plasticity – brain changes in response to behaviour. But unclear if cause or effect.
        • May include genetics, but psychosocial factors can also be linked to childhood stress, etc. So likely combination of biological and psychosocial factors.
  • Biological Basis of Alzheimer’s Disease
    • Most common disorder in dementia category, or neurocognitive disorders. Loss of cognitive functions. Memory also decreases. But normal motor functions are fine until later stages where they lose basic activities of daily living (ADL) – toileting, eating, bathing, etc.

Cause of disease is limited.

  • Brain tissue has decreased in size significantly – shrivelled up, atrophy.
    • It’s the cerebrum that often dramatically decreases in size. Severity of atrophy correlates with severity of dementia.
    • Starts in temporal lobes, important for memory.
    • Later, atrophy spreads to parietal and frontal lobes. Many other cognitive functions.
  • Under microscope, 3 main abnormalities:
    • loss of neurons,
    • plaques (amyloid, because plaques are made of beta-amyloid. Occur in spaces between cells, outside of neurons in abnormal clumps),
    • and tangles (neurofibrillary tangles, clumps of a protein tau. Located inside neurons. Develop proteins normally in the brain, but changed so it’s abnormal and causes them to clump together).
      • Not clear if they’re what’s killing neurons, or if they’re a by-product.
    • Group of neurons at base of cerebrum, called the nucleus basalis is often lost early in course of Alzheimer’s. Important for cognitive functions – send long axons to cerebral cortex and through cerebrum, and release acetylcholine. Contribute to cognitive functions of disease.
    • Synapses appear to not function clearly long before disease.
      • Also genetic mutations, many involved in processing of amyloid protein.
      • Also ApoE4 involved in metabolism of fats is strongly related to AD.
      • Also, high blood pressure increases risk of disorder too.
    • Things that decrease it – higher education, challenging jobs with difficult thinking.
  • Biological Basis of Parkinson’s Disease
    • Progressive neurological disorder involving motor abnormalities and neural too. A tremor, increased muscle tone, abnormal walking, and poor balance. Muscles are stiffer and slow with tremor. Later in disease when motor abnormalities are severe, patients may not be able to care for themselves.
    • Brains of patients have abnormalities visible to naked eye – in brainstem, the substantia nigra is less dark or not dark at all. Loss of ONLY dopaminergic neurons observed, suggesting 1 type involved. Motor abnormalities related to this.
      • Dopaminergic neurons in other areas are lost as well.
      • Substantia nigra is part of the basal ganglia, major role in motor functions and some mental functions. Receives info from many places in NS, and basal ganglia processes that info and sends it back to areas of cerebral cortex to influence areas such as motor cortex.
      • SN also projects to area called striatum, and loss of DA neurons causes most of neural abnormalities. Can see diseased neurons. Many contain lewy bodies in DA neurons, which contain a protein alpha synuclein, a normal protein in brain cells but in PD it appears clumped together.
    • Risk factors: genetic mutations in families with inherited form of disease, agricultural chemicals.
    • Leading candidate for treatment with stem cells since only 1 type of cell affected.
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