chapter 14 psychological disorders module 14.2 mood disorders schizophrenia autism spectrum...

Chapter 14Psychological Disorders

Module 14.2

Mood Disorders

Schizophrenia

Autism Spectrum Disorders

Module 14.3

Module 14.4

Mood Disorders

Mood Disorders

Unipolar disorder is characterized by alternating states of normality and depression.

Symptoms include:

Depression• Similar symptoms can result

from:– hormonal problems– head injuries– brain tumors– other illnesses

• Often comorbid with other disorders such as:– schizophrenia– substance abuse– anxiety– Parkinson’s disease

• Occurs at any age• 10% lifetime prevalence

Depression

• Childhood depression is equally common in both boys and girls.

• After puberty, depression is twice as common in females.

• The finding is consistent across cultures, suggesting a biological factor.

Genetics of Depression

• Studies of twins and adopted children suggest a moderate degree of heritability.

• Risk is elevated if one has a relative with early-onset depression (before age 30).

Genetics of Depression

• One gene has been identified that controls the serotonin transporter protein.– Protein controls the ability of

the axon to reabsorb the neurotransmitter after its release.

• Two “short forms” of the gene are associated with an increased likelihood of depression after stressful events.– Perhaps alters the way people

react to stressful events.

Depression and Hormones

• Hormones are also involved with depression.

• A likely trigger for an episode of depression is stress and the release of the hormone cortisol.

• Prolonged elevated levels exhaust the body’s energies, impair sleep and the immune system.– Set the stage for an episode

of depression.

Postpartum Depression• Occurs after giving birth.• Affects about 20% of women and most recover quickly.• More common among women who:

– have suffered depression at other times.– experience sever discomfort during the times around

menstruation.• May be associated with a drop in estradiol and

progesterone levels.

Depression and Brain Activity

• Depression is associated with:– Decreased activity in the

left prefrontal cortex– Increased activity in the

right prefrontal cortex• Many people become

seriously depressed after left-hemisphere damage.

• Occasionally, people with right hemisphere damage become manic.

Treatment of Depression: Antidepressant Drugs

• Categories of antidepressant drugs include:

1. Tricyclics prevent the presynaptic neuron from reabsorbing serotonin, dopamine, or norepinephrine

2. Selective Serotonin Reuptake Inhibitors (SSRI’s) block the reuptake of the neurotransmitter serotonin

Treatment of Depression: Antidepressant Drugs

3. Monoamine Oxidase Inhibitors (MAOI’s) block the enzyme monoamine oxidase that metabolizes serotonin into an inactive form

4. Atypical antidepressants work by inhibiting the reuptake of dopamine and to some extent, norepinephrine but not serotonin.

Treatment of Depression: Electroconvulsive Therapy (ECT)

• electrically induced seizure used for the treatment of severe depression

• used with patients who have not responded to antidepressant medication or who are suicidal

• fast-acting, but effects diminish rapidly

• best used in conjunction with other forms of therapy

Treatment of Depression: Electroconvulsive Therapy (ECT)

• Side effects include memory loss.– Memory loss can be

minimized if shock is localized to the right hemisphere.

• increases the proliferation of new neurons in the hippocampus

• alters expression of at least 120 genes in the hippocampus and frontal cortex

Treatment of Depression: Transcranial Magnetic Stimulation

• an intense magnetic field is applied to the scalp, to stimulate the neurons

• moderately effective

Treatment of Depression: Disruption of Sleep Patterns

• Disruption of sleep patterns is common in depression.– Typically fall asleep but

awaken early and are unable to get back to sleep.

– Enter REM sleep within 45 minutes and have an increased average number of eye movements during REM sleep.

• Sleep pattern disruption also increases the likelihood of depression.

Treatment of Depression: Disruption of Sleep Patterns

• A night of total sleep deprivation is the quickest known method of relieving depression.

• Half who experience relief become depressed again after the next night’s sleep.– Therefore, often best used in conjunction with other

therapies

Bipolar Disorder

Bipolar disorder (manic-depressive disorder) is characterized by the alternating states of depression and mania.

– Mania - restless activity, excitement, laughter, self-confidence, rambling speech, and loss of inhibition.

Bipolar Disorder• Bipolar disorder I - characterized

by full blown episodes of mania.• Bipolar disorder II - characterized

by much milder manic phases, called hypomania, of which anxiety and agitation are the primary symptoms.– Affects approximately 1% of

people.– Average age of onset is in the

early 20’s.– Brain’s use of glucose

increases during periods of mania and decreases during periods of depression.

Genetics of Bipolar Disorder

• Twin studies suggest monozygotic twins share a 50% concordance rate.

• Dizygotic twins, brothers, sisters or children share a concordance rate of 5-10%.

• Several genes are somewhat more common in people with the disorder.

• Genes simply increase the risk but do not cause the disorder.

Treatments for Bipolar Disorder

1. Lithium - a salt that prevents relapse in mania or depression

2. Anticonvulsant drugs such as valproate (depakote) and carbamazepine Usually prescribed for bipolar II.

These chemicals/drugs are used to stabilize mood:

Seasonal Affective Disorder (SAD)• form of depression that regularly occurs during a particular

season.• Patients with SAD have phase-delayed sleep and

temperature rhythms; most depressed people have phase-advanced patterns.

• Treatment often includes the use of very bright lights.– Most likely explanation is that the light affects serotonin

synapses and alters circadian rhythms.

Schizophrenia

• Schizophrenia is a disorder characterized by deteriorating ability to function in every day life and some combination of the following symptoms:

– Hallucinations: abnormal sensory experiences

– Delusions: unfounded beliefs

– Disorganized speech: rambling

or incoherent– Grossly disorganized behavior– Weak or absent signs of

emotion,

speech, and socialization– Inappropriate emotional

expression– Thought disorder: difficulty

using and understanding

abstract concepts

Schizophrenia: Inappropriate Emotional Expression

• Positive symptoms are behaviors that are present that should not be present.– hallucinations– delusions– disorganized speech

Schizophrenia: Inappropriate Emotional Expression

• Negative symptoms are behaviors that are absent that should be present, including:– weak social interaction– lack of emotional

expression– speech deficit– working memory deficit

• Negative symptoms are usually stable over time and difficult to treat.

Schizophrenia: Incidence Rates

• Schizophrenia affects about 1% of the population and ranges in severity.

• Can be either acute or chronic:– Acute - condition has a sudden onset and good

prospect for recovery.– Chronic - condition has a gradual onset and a long-

term course.

Schizophrenia: Incidence Rates• Occurs in all parts of the world, but is 10 to 100 times more

common in the United States and Europe than in third-world countries.

• More common in men than in women by a ratio of about 7 to 5.• More severe and earlier age of onset for men (early 20’s

versus late 20’s).• Likelihood increases as the age of the father increases.

Schizophrenia: Genetics

• Twin studies suggest a genetic component.

• Monozygotic twins have a much higher concordance rate (agreement) than dizygotic twins.– But monozygotic twins only

have a 50% concordance rate.

• Greater similarity between dizygotic twins than siblings suggests a prenatal/postnatal environmental effect.

Schizophrenia: Genetics

• Attempt to link adult-onset schizophrenia to an identified gene have provided inconsistent results.

• Schizophrenia most likely results from environmental factors in addition to biological factors.

Schizophrenia:Neurodevelopmental Hypothesis

• suggests abnormalities in the prenatal or neonatal development of the nervous system.

• Leads to subtle abnormalities of brain anatomy and major abnormalities in behavior.

• Abnormalities could result from genetics, difficulty during birth, or a combination of both.

Schizophrenia:Neurodevelopmental Hypothesis

• Supporting evidence includes:– Several kinds of prenatal or neonatal difficulties are linked to

later schizophrenia.– People with

schizophrenia have

minor brain

abnormalities that

originate early in life.• Abnormalities of early

development could

impair behavior in

adulthood.

Schizophrenia:Neurodevelopmental Hypothesis

• Prenatal risk factors increasing the likelihood of schizophrenia include:– Poor nutrition of the mother

during pregnancy.– Premature birth.– Low birth weight.– Complications during delivery.

• Head injuries in early childhood are also linked to increased incidence of schizophrenia.

Schizophrenia:Neurodevelopmental Hypothesis

• Mother/child blood type differences increase the likelihood of schizophrenia.

• If the mother has a Rh-negative blood type and the baby is Rh-positive, the child has about twice the probability of developing schizophrenia.

Schizophrenia:Neurodevelopmental Hypothesis

• The season-of-birth effect refers to the tendency for people born in winter to have a slightly (5% to 8%) greater probability of developing schizophrenia.– More pronounced in

latitudes far from the equator.

– Might be explained by complications of delivery, nutritional factors, or increased likelihood of viral infections

Schizophrenia: Brain Abnormalities• Schizophrenia is associated with mild brain abnormalities:

– Less than average gray and white matter • Strongest deficits found in the left temporal and

frontal lobe of the cortex– Larger than normal ventricles– Smaller than normal hippocampus

• Schizophrenics have deficits in working memory.

Schizophrenia: Development

• Schizophrenia typically develops after the age of 20 but many show sign at an earlier age.– Deficits in attention, memory

and impulse control.• Prefrontal cortex damage may

not show signs of damage until later. – Structure matures slowly and

does not do much at an earlier age.

– Neurodevelopmental hypothesis is thus plausible but not firmly established.

Schizophrenia: Treatment

• Antipsychotic/neuroleptic drugs are drugs that tend to relieve schizophrenia and similar conditions.

• Chlorpromazine (thorazine) is a drug used to treat schizophrenia that relieves the positive symptoms of schizophrenia.– Relief usually experienced

2-3 weeks after taking the drug, which must be taken indefinitely.

Schizophrenia: Treatment

• Two chemical families of drugs used to treat schizophrenia include:

1. Phenothiazines - includes chlorpromazine

2. Butyrophenones - includes halperidol (Haldol)

• Both drugs block dopamine synapses.

Dopamine Hypothesis of Schizophrenia

• suggests that schizophrenia results from excess activity at dopamine synapses in certain areas of the brain.

• Substance-induced psychotic disorder is characterized by hallucinations and delusions resulting from repeated large doses of amphetamines, methamphetamines, or cocaine.– Each prolongs activity of dopamine at the synapse,

providing further evidence for dopamine hypothesis.

Glutamate Hypothesis of Schizophrenia • suggests the problem relates partially to deficient activity

at glutamate receptors– especially in the prefrontal cortex

• Schizophrenia is associated with lower than normal release of glutamate and fewer receptors in the prefrontal cortex and hippocampus.

• Support comes from the effects of phencyclidine (PCP/angel dust).– Inhibits the NMDA glutamate receptors.– Produces positive and negative symptoms at high doses.

Schizophrenia: Treatment• The mesolimbocortical

system is a set of neurons that project from the midbrain tegmentum to the limbic system.– Site where drugs that

block dopamine synapses produce their benefits.

• Drugs also block dopamine in the mesostriatal system, which project to the basal ganglia.– Result is tardive

dyskinesia, characterized by tremors and other involuntary movements.

Schizophrenia: Treatment

• Second-generation antipsychotics (atypical antipsychotics) are a class of drugs used to treat schizophrenia but seldom produce movement problems.– Examples: clozapine, amisulpride, risperidone,

olanzapine, aripiprazole.• More effective at treating the negative symptoms and

are now more widely used.

Schizophrenia

• Schizophrenia cannot be explained by a single gene or single transmitter.

• Dopamine and glutamate may play important roles in schizophrenia to different degrees in different people.

• Schizophrenia involves multiple genes and abnormalities in dopamine, glutamate, serotonin and GABA.

Autism Spectrum Disorders

• Primary characteristics:– Deficits in social and emotional

exchange– Deficits in gestures, facial

expression and other nonverbal communication

– Repetitive behaviors– Resistance to change in routine– Unusually weak or strong

emotional reactions

Autism Spectrum Disorders

• Worldwide prevalence estimated at 1 in 160 people

• More common in boys than girls

Autism Spectrum Disorders

• Often comorbid with Attention Deficit Disorder (ADD)• Can involve cerebellum, resulting in movement deficit

Autism Spectrum Disorders

• Many genes have been linked to autism, but no single gene is found in a high percentage of people with autism

• Most cases probably result from new mutations or microdeletions in multiple genes.