chapter fifteen alcoholism, mood disorders, and schizophrenia
TRANSCRIPT
Alcoholism
Defined-cannot stop drinking or control the amount you consume
Genetics
Two Types of Alcoholism
Type 1 Type II
Less genetic Stronger genetic basis
Develops gradually Rapid, early onset
Affects men and women equally Overwhelmingly men
Concordance rates in twins is .55
Figure 15.3 Design for studies of predisposition to alcoholismSons of alcoholic fathers are compared to other young men of the same age and same current drinking habits. Any behavior that is more common in the first group
is presumably a predictor of later alcoholism.
Alcohol Metabolism and Antabuse
Antabuse
Drug used to treat alcoholism
Mechanism-stops metabolism of alcohol
Results in nausea, headache and stomach pain when alcohol is consumed
Only moderately effective
Risk Factors for Alcohol Abuse
Sons of alcoholics report low intoxication after drinking
Sons of alcoholics are more likely to report stress relief from drinking
Depression
Major Depressive DisorderDefined-long-term sadness and helplessnessEtiology
Observed more often in women than menPeak frequency between 25 and 44About 19% of all people suffer a bout of depression at least
once in their livesGenetics
Depression does have a genetic linkGene has not been located
Depression
Triggering Depressive Episodesdepression is episodicCan be triggered by an event (ex: death of a loved one, birth of a
child, etc)Potential Physiological Mechanisms
Abnormalities of Hemispheric DominanceDepressed people have more activity in the right prefrontal cortex
than the left prefrontal cortexDepression more commonly follows left-hemisphere damage
VirusesBorna virus is found more commonly in depressed populations
than in non-depressed populations
Depression
TreatmentsAntidepressants
Tricyclics-prevent reuptake of serotonin or norepinephrine/epinephrine
MAO Inhibitors-block MAO from breaking down serotonin and norepinephrine/epinephrine
SSRI’s-block reuptake of serotoninAtypical antidepressants-miscellaneous groupECT
Applied every other day for two weeksMuscle relaxants and anesthetics minimize discomfortMemory loss can be a side-effect (limited if shock is
given to right hemisphere onlyAltered Sleep Patterns
Treat patient like someone with difficulty adjusting to changing time zones
Figure 15.7 Routes of action of antidepressantsTricyclics block the reuptake of dopamine, norepinephrine, or serotonin. SSRIs
specifically block the reuptake of serotonin. MAOIs block the enzyme MAO, which converts dopamine, norepinephrine, or serotonin into inactive chemicals.
Atypical antidepressants have varying effects.
Depression
Physiology of Depression
Two Conclusions
Mood depends on the effects of a combination of transmitters
Different depressed people have somewhat different transmitter abnormalities
Video
Bipolar Disorder
Defined-alternate between mania and depressionEtiology
May last only days or for a year or more1% of people have a mild case at some time in lifeAverage age of onset is early 20’s
GeneticsConcordance rate is .50No specific gene has been identified
Bipolar Disorder
Treatments
Lithium
Stabilizes mood
Mechanism unknown but likely involves second messenger systems
Anticonvulsant drugs
Mechanism of action is on second messenger systems
Seasonal Affective Disorder
Defined-depression that regularly recurs in a particular season
Usually treated by bright light therapy
Schizophrenia
Characteristics
Deteriorating ability to function
Accompanied by delusions, hallucinations, thought disorder, movement disorder and inappropriate emotional expression
Behavioral Symptoms
Positive Symptoms-behavior that are present that should be absent
Delusions, hallucinations, thought disorders
Negative Symptoms-behavior that is absent that should be present
Weak social interactions, emotional expression, speech, and working memory
Schizophrenia
Characteristics Cont’d
Acute-sudden onset with good prospects for recovery
Chronic-gradual onset and a long-term course of treatment and resistance
Schizophrenia
Etiology
About 1.3% of people will suffer from schizophrenia at some point in their lives
More common in developed countries
Equal occurrence for men and women
Onset is usually in the 20’s
Schizophrenia
Genetics
Concordance rate is 50%
However, genes are not the only influence
A gene has not been located for schizophrenia
Figure 15.15 Probabilities of developing schizophreniaThe closer the genetic relationship to someone with schizophrenia, the higher
the probability of developing it oneself.
Hypotheses of Causation in Schizophrenia
NeurodevelopmentalEither genes or difficulties early in life impair brain development in
ways that lead to schizophrenic-like symptoms in early adulthoodDopamine Hypothesis-Excess dopamine activity causes behavioral
changes associated with schizophreniaSupported by drug treatments that target dopamine
Glutamate Hypothesis-the problem is deficient glutamate activityPhencyclidine-Inhibits glutamate type NMDA receptors and produces
both positive and negative symptoms of schizophrenia