Download Eagleman Ch 16. Neurological and Psychiatric Disorders

16: Neurological and
Psychiatric Disorders
Cognitive Neuroscience
David Eagleman
Jonathan Downar
Chapter Outline
Alzheimer’s Disease: Burning Out with
Age?
 Frontotemporal Dementia: Like a Cancer
of the Soul
 Huntington’s Disease: A Genetic Rarity, in
Two Senses
 Tourette Syndrome: A Case of Involuntary
Volition?

2
Chapter Outline
Obsessive-Compulsive Disorder:
Neurological or Psychiatric?
 Schizophrenia: A Dementia of the Young
 Bipolar Disorder
 Depression: A Global Burden

3
Alzheimer’s Disease: Burning
Out with Age?
Dementias are neurologic disorders
characterized by slow deterioration of
higher cognitive functions.
 Such functions include language, memory,
judgement, and emotion.
 Alzheimer’s disease or Alzheimer’s
dementia is thought to affect about 24
million people world-wide.

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Alzheimer’s Disease: Burning
Out with Age?
5
Alzheimer’s Disease: Burning
Out with Age?
The major deficit of Alzheimer’s is the loss
of episodic memory.
 Executive functions decline throughout
Alzheimer’s disease.
 Biological markers of Alzheimer’s disease
include amyloid-beta plaques and
neurofibrillary tau tangles.

6
Alzheimer’s Disease: Burning
Out with Age?
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Alzheimer’s Disease: Burning
Out with Age?
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Alzheimer’s Disease: Burning
Out with Age?
Most cases of Alzheimer’s disease occur
in individuals over age 60.
 The epsilon 4 variant of the apolipoprotein
E (ApoE4) gene seems to increase the
risk of developing the disease.
 Genetic forms of Alzheimer’s disease
account for only a small percentage of
cases.

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Alzheimer’s Disease: Burning
Out with Age?
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Alzheimer’s Disease: Burning
Out with Age?

Treatment of Alzheimer’s disease
are currently no cures for Alzheimer’s
disease.
 No medications significantly slow down or
reverse the progression of the disease.
 Acetylcholinesterase inhibitors and NMDA
glutamate receptor antagonists sometimes
slow the progression of the disease.
 There
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Alzheimer’s Disease: Burning
Out with Age?
A potential treatment uses the immune
system to remove plaques, but this has
not resulted in any clinical improvement.
 Social, mental, and physical activity can
decrease the risk and severity of
Alzheimer’s disease.

12
Frontotemporal Dementia: Like a
Cancer of the Soul
This dementia results from progressive
atrophy of the brain.
 This is most common in the inferior frontal
lobes and anterior temporal lobe.
 The age of onset is typically about 40 – 50
years of age.
 Personality and social behaviors change
significantly.

13
Frontotemporal Dementia: Like a
Cancer of the Soul
14
Frontotemporal Dementia: Like a
Cancer of the Soul
Behavioral variant frontotemporal
dementia (bvFTD) is most common.
 This is characterized by progressive
semantic dementia, personality changes
and loss of empathy.
 Frontotemporal dementia is sometimes
associated with an increase in creativity.

15
Frontotemporal Dementia: Like a
Cancer of the Soul
16
Huntington’s Disease: A Genetic
Rarity, in Two Senses
Patients perform restless involuntary
movements of the face, trunk, and limbs.
 It commonly also includes psychiatric
symptoms such as depression, apathy,
anxiety, delusions, and hallucinations.
 The biological cause is degeneration of
the anterior caudate nucleus of the
striatum.

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Huntington’s Disease: A Genetic
Rarity, in Two Senses
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Huntington’s Disease: A Genetic
Rarity, in Two Senses
19
Huntington’s Disease: A Genetic
Rarity, in Two Senses
Huntington’s disease is caused by the
mutation of an autosomal dominant gene.
 This mutation encodes the inclusion of a
trinucleotide repeat of the sequence CAG
in the final protein.

 Most
people have fewer than 28 CAG
repeats, and this results in no issues.
 Individuals with more than 35 repeats are at
an increased risk of developing the disease.
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Huntington’s Disease: A Genetic
Rarity, in Two Senses
Risk factors for Huntington’s disease
include both genetic and environmental
factors.
 Treatment for Huntington’s disease
involves dopamine receptor antagonists.
 These relieve some of the motor and
psychiatric symptoms.

21
Huntington’s Disease: A Genetic
Rarity, in Two Senses
22
Tourette Syndrome: A Case of
Involuntary Volition?
In Tourette syndrome, the individual
repeats purposeless movements of the
face, head, shoulders, or hands.
 There are also verbal tics, which are
purposeless noises like throat-clearing and
snorting or meaningless phrases.

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Tourette Syndrome: A Case of
Involuntary Volition?
Tourette syndrome is typically a disorder
of childhood.
 Studies suggest there is a genetic basis to
Tourette syndrome, but no gene has been
isolated.

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Tourette Syndrome: A Case of
Involuntary Volition?

Pediatric Autoimmune Neuropsychiatric
Disorder Associated with group A
Streptococcal infection (PANDAS)
 This
is characterized by the tics of Tourette
syndrome or the intrusive thoughts and
behaviors of obsessive compulsive disorder.
 Sometimes occurs in patients shortly after
they have had a throat infection caused by the
bacteria Group A streptococcus.
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Tourette Syndrome: A Case of
Involuntary Volition?
Patients have a decrease in gray matter in
the caudate nucleus and lateral motor and
premotor cortex.
 Gray matter is thinner in medial motor
areas.

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Tourette Syndrome: A Case of
Involuntary Volition?
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Tourette Syndrome: A Case of
Involuntary Volition?
Therapy for Tourette syndrome includes
education and acceptance.
 Neurolepic medications are prescribed for
the most severe cases, where the tics
interfere significantly with daily life.

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Obsessive-Compulsive Disorder:
Neurological of Psychiatric?
“Neurological” disorders and “psychiatric”
disorders are grouped based on the nature
of the condition.
 Conditions with an observable brain
abnormality were considered neurological.

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Obsessive-Compulsive Disorder:
Neurological of Psychiatric?

A more modern criteria based on the
symptoms.
 Psychiatric
conditions impact emotion,
motivation, social behaviors, personality, or
reality testing.
 Neurological conditions impact strength,
movement, sensory perception, memory,
attention, or level of consciousness.
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Obsessive-Compulsive Disorder:
Neurological of Psychiatric?
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Obsessive-Compulsive Disorder:
Neurological of Psychiatric?
Obsessive-compulsive disorder is a
psychiatric disorder that affects about 2 –
3% of the population.
 Symptoms include obsessions (intrusive,
disturbing thoughts) and compulsions
(stereotyped, ritualized behaviors).

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Obsessive-Compulsive Disorder:
Neurological of Psychiatric?
Obsessions include contamination, fear of
committing inappropriate acts, symmetry
and number, and hoarding.
 The most common age of onset for
symptoms of obsessive-compulsive
disorder is either about age 11 or 23.

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Obsessive-Compulsive Disorder:
Neurological of Psychiatric?
34
Obsessive-Compulsive Disorder:
Neurological of Psychiatric?
There is increased activity in the circuits
connecting the basal ganglia to the
orbitofrontal, anterior cingulate, and
dorsomedial prefrontal cortex.
 The pattern of activity differs depending on
the types of obsession.

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Obsessive-Compulsive Disorder:
Neurological of Psychiatric?
36
Obsessive-Compulsive Disorder:
Neurological of Psychiatric?
Cognitive behavioral therapy addresses
cognitive distortions and decreases
anxiety.
 Medications than increase serotonin
reduce the obsessions, compulsions, and
anxiety.
 Neuroleptics are sometime prescribed for
severe cases.

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Schizophrenia: A Dementia of
the Young
Schizophrenia is characterized by loss of
contact with reality.
 The age of onset is typically around early
adulthood.
 Schizophrenia affects about 1% of the
world’s population.

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Schizophrenia: A Dementia of
the Young

Positive symptoms include hallucinations
and delusions.
 Delusions
include paranoid delusions,
delusions of reference, delusions of passivity,
and somatic delusions.

Negative symptoms include poverty of
speech, apathy, social withdrawal, and
loss of emotion.
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Schizophrenia: A Dementia of
the Young
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Schizophrenia: A Dementia of
the Young
Antipsychotic medications treat the
positive symptoms, but do not treat the
negative symptoms.
 Such medications often cause unwanted
side effects.
 Second-generation antipsychotic
medications are no better at treating the
negative symptoms.

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Schizophrenia: A Dementia of
the Young
There is a genetic basis to schizophrenia,
but no specific genes have been identified.
 Environmental factors during fetal
development or early life seem important
in the incidence of schizophrenia.

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Schizophrenia: A Dementia of
the Young
43
Schizophrenia: A Dementia of
the Young

Neurodevelopmental factors
 Abnormal
pruning of neurons
 Smaller cell bodies of neurons
 Decreased functioning of inhibitory GABA
interneurons in the cortex
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Schizophrenia: A Dementia of
the Young
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Schizophrenia: A Dementia of
the Young
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Schizophrenia: A Dementia of
the Young

Dopamine hypothesis
 There
is too much dopamine signaling or the
dopamine receptors are oversensitive.
 The first-generation antipsychotic drugs were
dopamine D2 receptor antagonists.
 Drugs that increase dopamine, such as
amphetamines and cocaine, can mimic the
positive symptoms of schizophrenia.
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Schizophrenia: A Dementia of
the Young
48
Schizophrenia: A Dementia of
the Young

Glutamate hypothesis
 Schizophrenia
is caused by too little
glutamate neurotransmission.
 NMDA receptor antagonists, like ketamine,
can mimic both the positive and negative
symptoms of schizophrenia.
 Many of the genes associated with
schizophrenia affect NMDA glutamate
receptors.
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Schizophrenia: A Dementia of
the Young
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Bipolar Disorder
Normal mood alternates with periods of
depression and mania.
 This affects 1% of the population and a
milder form may affect as much as 4-5%
of the population.
 The age of onset is about 20 years of age.
 There is a genetic basis to the condition,
but no specific genes have been identified.

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Bipolar Disorder
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Bipolar Disorder

Individuals with bipolar disorder show
thinner gray matter in the
 Bilateral
ventrolateral frontal cortex
 Bilateral anterior insula
Dorsomedial prefrontal cortex
 Subgenual cingulate cortex

Some of these regions are also affected in
unipolar depression.
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Bipolar Disorder
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Bipolar Disorder

Common treatments include
 Mood-stabilizing
drugs, such as lithium
 Anti-dpileptic drugs
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Bipolar Disorder
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Depression: A Global Burden
Impact of Depression
 Causes of Depression
 Neurochemical Effects of Depression on
Brain
 Functional Effect of Depression on the
Brain
 Treatment of Depression

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Impact of Depression
Depression is characterized by a low
mood that makes it difficult to carry out the
functions necessary for daily life.
 Individuals with depression do not take
pleasure in typical activities, lack
motivation and energy, and have altered
sleep patterns and appetite.

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Impact of Depression
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Impact of Depression
The worldwide incidence of depression is
5% at any one time.
 In the United States, the incidence is 5%
for men and 10% for women.
 Lifetime incidence is roughly double the
one-time incidence rates.
 The cost of depression is estimated to be
about $80 billion per year in the U.S.

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Impact of Depression
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Causes of Depression
Mood disorders run in families, suggesting
a genetic basis.
 Depression may be an evolutionary
adaptation to suffering a trauma or defeat
 Depression causes the individual to stay
away from opponents and predators while
waiting for better times.

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Causes of Depression
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Neurochemical Effects of
Depression on Brain

Monoamine hypothesis of depression
 There
is a shortage of the monoamine
neurotransmitters.
 By inhibiting the enzyme monoamine oxidase,
which breaks down these transmitters, mood
will be improved.
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Neurochemical Effects of
Depression on Brain

Serotonin hypothesis
 More
specific than the monoamine
hypothesis.
 There is, specifically, a shortage of serotonin.
 Selective serotonin reuptake inhibitors
specifically affect serotonin levels.
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Neurochemical Effects of
Depression on Brain

Other biological theories
 There
are abnormalities with glutamate
neurotransmission.
 There are low levels of the neuronal growth
factor brain-derived neurotrophic factor
(BDNF).
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Neurochemical Effects of
Depression on Brain
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Functional Effect of Depression
on the Brain

Networks of brain areas are under- and
over-activated in individuals with
depression.
 The
subgenual cingulate cortex is consistently
hyperactive.
 This hyperactivity returns to normal following
successful treatment of depression.
 The dorsolateral and dorsomedial prefrontal
cortex tend to be less active.
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Functional Effect of Depression
on the Brain
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Functional Effect of Depression
on the Brain
The pattern of hyper- and hypo-active
brain regions differs across individuals.
 Current research is examining the
interactions between different brain
regions.

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Treatment of Depression

Three major treatments are used for
individuals with depression
 Psychotherapy
 Pharmacotherapy
 Somatic
therapy
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Treatment of Depression
In psychotherapy, the patient interacts with
a clinician to work through the causes of
their depression.
 Cognitive therapy is about as effective as
pharmacotherapy
 The effects seem to persist for a longer
time than the medication does.

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Treatment of Depression
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Treatment of Depression

Anti-depressant medications include
 Monoamine
oxidase inhibitors (MAOIs)
 Tricyclic antidepressants (TCAs)
 Selective serotonin reuptake inhibitors
(SSRIs)
All of these are about equally effective.
 Different medications are more or less
effective for different individuals.

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Treatment of Depression
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Treatment of Depression
Somatic therapies are more invasive.
 These include

 Repetitive
transcranial magnetic stimulation
 Electroconvulsive therapy
 Deep brain stimulation
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