Causes of Mental IllnessCauses of Mental Illness

Lecture 13Lecture 13

The precise causes (etiology) of most mental The precise causes (etiology) of most mental disorders are not knowndisorders are not known

But the broad forces that shape them But the broad forces that shape them are are known: these are known: these are biologicalbiological, , psychologicalpsychological, , and and social/culturalsocial/cultural factors. factors.

These causes are generally viewed as a These causes are generally viewed as a product of the product of the interactioninteraction between biological, between biological, psychological, and sociocultural factors.psychological, and sociocultural factors.

The brain and behavior are inextricably linked The brain and behavior are inextricably linked

Psychological and sociocultural phenomena Psychological and sociocultural phenomena involve structural changes in the neurons and involve structural changes in the neurons and neuronal circuitsneuronal circuits

Psychological and sociocultural events and Psychological and sociocultural events and phenomena continue to have meaning for phenomena continue to have meaning for mental health and mental illness.mental health and mental illness.

Bio-psycho-social Model of Bio-psycho-social Model of DiseaseDisease

George L. Engel, (1977)George L. Engel, (1977)

The model lacks The model lacks sufficient specificitysufficient specificity to make to make cause- and- effect predictionscause- and- effect predictions

The model takes a broad view that biological The model takes a broad view that biological factors are not the only cause of mental illness, factors are not the only cause of mental illness, environmental and psychological factors are environmental and psychological factors are also important.also important.

The relative importance or role of any one factor in The relative importance or role of any one factor in causation often varies. causation often varies.

For example, schizophrenia is linked strongly to For example, schizophrenia is linked strongly to genetic factorsgenetic factors

But psycho-social factors modify expression and But psycho-social factors modify expression and outcome of such disorders. outcome of such disorders.

Likewise, some mental disorders such as (PTSD), are Likewise, some mental disorders such as (PTSD), are mostly environmental in naturemostly environmental in nature

But pre-trauma vulnerability also determines the onset But pre-trauma vulnerability also determines the onset of PTSDof PTSD

Similarly depression can be caused by stressful life Similarly depression can be caused by stressful life events as well as due to genetic predispositionevents as well as due to genetic predisposition

Understanding Correlation, Understanding Correlation, Causation, and ConsequencesCausation, and Consequences

Three terms must be distinguished in the etiology of Three terms must be distinguished in the etiology of mental illness:mental illness:

correlationcorrelation, , causationcausation, and , and consequencesconsequences

A biological change in the brain could be a correlate, a A biological change in the brain could be a correlate, a cause of, or an effect of the mental disorder.cause of, or an effect of the mental disorder.

Researchers usually start by noticing correlations to Researchers usually start by noticing correlations to find out “risk factors”find out “risk factors”

Risk factors are biological, psychological, or socio-Risk factors are biological, psychological, or socio-cultural variables that increase the probability for cultural variables that increase the probability for developing a disorder and antedate its onset.developing a disorder and antedate its onset.

Establishing Establishing causationcausation of mental health and of mental health and mental illness is extremely difficult because mental illness is extremely difficult because experiments with humans may be limited.experiments with humans may be limited.

Thus most information comes from correlational Thus most information comes from correlational research.research.

Correlational research must confirm evidence Correlational research must confirm evidence from biological & chemical findings in animal from biological & chemical findings in animal models.models.

Consequences are defined as the later Consequences are defined as the later outcomes of a disorder.outcomes of a disorder.

For example, in depression : increased For example, in depression : increased mortality from either suicide or medical illnessmortality from either suicide or medical illness

Thus, the bio-psycho-social model holds that Thus, the bio-psycho-social model holds that biological, psychological, or social factors may biological, psychological, or social factors may be be causescauses, , correlatescorrelates, and/or , and/or consequencesconsequences in relation to mental health and mental illness. in relation to mental health and mental illness.

Biological Influences on Mental Biological Influences on Mental Health and Mental IllnessHealth and Mental Illness

Biological and physical influences on mental Biological and physical influences on mental health and mental illness are far reaching.health and mental illness are far reaching.

Categories include genes, infections, physical Categories include genes, infections, physical trauma, nutrition, hormones, and toxins etc.trauma, nutrition, hormones, and toxins etc.

The Genetics of Behavior and The Genetics of Behavior and Mental IllnessMental Illness

Genes influence behavior: an established factGenes influence behavior: an established fact

Mostly defects in Mostly defects in multiplemultiple genes are the cause genes are the cause

The human genome project : will provide help The human genome project : will provide help

Clinical medicine is studying heredity effectsClinical medicine is studying heredity effects

Mutation in genes (e.g., in Huntington’s disease and Mutation in genes (e.g., in Huntington’s disease and cystic fibrosis)cystic fibrosis)

The transmission of a trait due to a single gene in the The transmission of a trait due to a single gene in the human genome is called human genome is called MendelianMendelian transmission transmission

The genes already have been identified for almost all The genes already have been identified for almost all Mendelian disordersMendelian disorders

Mental illnesses are genetically complexMental illnesses are genetically complex

Important to study the interaction of genes with Important to study the interaction of genes with environmental factors in mental illnessenvironmental factors in mental illness

Genes : significant in their aggregate Genes : significant in their aggregate contribution to riskcontribution to risk

The Human Genome Project & modern The Human Genome Project & modern technologies will help in identification of specific technologies will help in identification of specific genesgenes

This information about genes will be of the This information about genes will be of the highest importance because:highest importance because:

Genes are the blueprints of cells,Genes are the blueprints of cells, Provide clues to critical times for interventionProvide clues to critical times for intervention Provide insight into environmental risk factorsProvide insight into environmental risk factors

Once a disorder is established as running in families, Once a disorder is established as running in families, the next step is to determine its the next step is to determine its heritabilityheritability, then its , then its mode of transmissionmode of transmission, and, lastly, its , and, lastly, its locationlocation through genetic mapping.through genetic mapping.

Twin studies: one powerful method for estimating Twin studies: one powerful method for estimating heritability heritability

Identical twins: share the exact genetic inheritance Identical twins: share the exact genetic inheritance

Fraternal twins: share only 50 percent of their genetic Fraternal twins: share only 50 percent of their genetic inheritanceinheritance

If a disorder is heritable, identical twins have a higher If a disorder is heritable, identical twins have a higher concordanceconcordance

Twin studies do not furnish information about Twin studies do not furnish information about whichwhich or or how manyhow many genes are involved. genes are involved.

Environmental factors can be significant even Environmental factors can be significant even with a high level of heritability.with a high level of heritability.

Environmental factors may even protect against Environmental factors may even protect against the disorder (if having less risk factors)the disorder (if having less risk factors)

Infectious InfluencesInfectious Influences

Infectious agents can cause mental disorders Infectious agents can cause mental disorders

Examples: Examples: ““general paresis”: a late manifestation of general paresis”: a late manifestation of

syphilissyphilis

Infectious agent—Infectious agent—Treponema pallidum Treponema pallidum ——caused “Neurosyphilis”caused “Neurosyphilis”

HIV-associated dementia HIV-associated dementia

HIV-associated dementia: 15 percent to 44 HIV-associated dementia: 15 percent to 44 percent prevalence.percent prevalence.

Caused indirectly by infection of immune cells Caused indirectly by infection of immune cells known as known as macrophages.macrophages.

Other mental disorders caused by infectious Other mental disorders caused by infectious agents: agents: herpes simplex encephalitisherpes simplex encephalitis, , measles encephalomyelitismeasles encephalomyelitis, , rabies rabies encephalitisencephalitis, and , and chronic meningitis.chronic meningitis.

PANDASPANDAS Abrupt onset of obsessive-compulsive disorder Abrupt onset of obsessive-compulsive disorder

symptoms soon after a symptoms soon after a streptococcal streptococcal pharyngitis.pharyngitis.

PANDAS : PANDAS : pediatric autoimmune pediatric autoimmune neuropsychiatric disorders associated neuropsychiatric disorders associated withwith streptococcal infectionstreptococcal infection..

PANDAS are caused by antibodies against the PANDAS are caused by antibodies against the strep infection that attack the child’s brain. strep infection that attack the child’s brain.

Psychosocial Influences on Psychosocial Influences on Mental Health and Mental IllnessMental Health and Mental Illness

Stressful life events, affect (mood and level of Stressful life events, affect (mood and level of arousal), & personality are prominent psychological arousal), & personality are prominent psychological influences. influences.

Social influences include parents, socioeconomic Social influences include parents, socioeconomic status, racial, cultural, and religious background, and status, racial, cultural, and religious background, and interpersonal relationships. interpersonal relationships.

Theories of individual behavior and personality : Theories of individual behavior and personality : psychodynamicpsychodynamic theories, theories, behaviorismbehaviorism, and , and socialsocial learninglearning theories. theories.

Psychodynamic TheoriesPsychodynamic Theories

Behavior is the product of underlying conflictsBehavior is the product of underlying conflicts

Two major assumptions: Two major assumptions: (1) that much of mental life is unconscious, and (1) that much of mental life is unconscious, and (2) that past experiences, especially in early (2) that past experiences, especially in early

childhood, shape how a person feels and childhood, shape how a person feels and behaves throughout lifebehaves throughout life

Three parts of personality: the id, the ego, and Three parts of personality: the id, the ego, and the superego. the superego.

The id : unconscious part The id : unconscious part

Ego : rational and reasonable part of personalityEgo : rational and reasonable part of personality

Ego mediates between the conflicting tendencies of Ego mediates between the conflicting tendencies of the id and the superego.the id and the superego.

Superego : a person’s conscience Superego : a person’s conscience

If the ego is unable to mediate between the id and If the ego is unable to mediate between the id and the superego, psychological distress and symptoms the superego, psychological distress and symptoms of mental disorders will occur.of mental disorders will occur.

Conflicts must be understood & resolved.Conflicts must be understood & resolved.

Behaviorism and Social Learning Behaviorism and Social Learning TheoryTheory

Behaviorism or learning theory : personality is Behaviorism or learning theory : personality is the sum of an individual’s overt behaviors.the sum of an individual’s overt behaviors.

Behavior modification: application to treatment Behavior modification: application to treatment of mental problemsof mental problems

LearningLearning : behavior change molded by : behavior change molded by experience, accomplished through either experience, accomplished through either classicalclassical or or operantoperant conditioning. conditioning.

Classical conditioningClassical conditioning

Grounded in the research of Ivan PavlovGrounded in the research of Ivan Pavlov

It explains why some people react to formerly It explains why some people react to formerly neutralneutral stimuli in their environment. stimuli in their environment.

Example : Pavlov’s experiment with a dogExample : Pavlov’s experiment with a dog

Dogs learned to salivate merely at the sound of Dogs learned to salivate merely at the sound of the bell, without any food in sight due to the bell, without any food in sight due to conditioning. conditioning.

Operant conditioningOperant conditioning Described and coined by B. F. SkinnerDescribed and coined by B. F. Skinner

A voluntary response is strengthened or A voluntary response is strengthened or attenuated, depending on its association with attenuated, depending on its association with positive or negative consequences.positive or negative consequences.

Positive & Negative reinforcementPositive & Negative reinforcement

Maladaptive behaviors can be unlearned Maladaptive behaviors can be unlearned through behavior modification or therapy.through behavior modification or therapy.

Social Learning TheorySocial Learning Theory

The movement beyond behaviorism: by Albert The movement beyond behaviorism: by Albert Bandura Bandura

Greater emphasis on observational learning or Greater emphasis on observational learning or modelingmodeling

People’s cognitions—their views, perceptions, People’s cognitions—their views, perceptions, and expectations toward their environment—and expectations toward their environment—affect what they learn.affect what they learn.

ConclusionConclusion : The Integrative Science : The Integrative Science of Mental Illness and Healthof Mental Illness and Health

Findings from different disciplines of the Findings from different disciplines of the mental health have contributed in the mental health have contributed in the study of mental illness and mental health.study of mental illness and mental health.

““Cognitive neuroscience”.Cognitive neuroscience”.