nsc chapter 22

What percentage of the population is affected by schizophrenia?

1%

What is the key symptom of schizophrenia?

Impaired logical thought

What are positive symptoms in schizophrenia?

Hallucinations, delusions, and excited motor behavior

What do positive symptoms involve?

Abnormal behaviors that are gained

Are positive symptoms usually acute or chronic?

Acute

Do positive symptoms respond well to medication?

Yes

What are negative symptoms in schizophrenia?

Slow thought/speech, emotional withdrawal, and blunted affect

What do negative symptoms involve?

Loss of normal functions

What are cognitive symptoms in schizophrenia?

Disorganized thoughts, trouble concentrating, and difficulty following instructions

What is the significance of the 48% concordance rate in monozygotic twins?

It shows that schizophrenia is partly genetic but also influenced by environment

How do brain scans differ between affected and unaffected identical twins?

Affected twins show enlarged ventricles and reduced brain tissue

What does a higher ventricle-to-brain ratio indicate in schizophrenia patients?

Brain volume loss and structural abnormalities

What is the risk of developing schizophrenia for first-degree relatives like children or siblings?

6% to 17%

What kind of twins have the highest risk of developing schizophrenia if their twin is affected?

Monozygotic (identical) twins

What causes schizophrenia according to the threshold model?

A combination of genetic vulnerability and environmental exposures

What is epigenetics?

The study of how environmental factors change gene expression without changing the DNA sequence

How can environmental factors affect genes in schizophrenia?

They can upregulate or downregulate gene function

What are two major epigenetic mechanisms?

DNA methylation and histone modification

What does it mean that people with the same genome can have different outcomes?

Gene expression can be altered by environmental factors (epigenetics)

What environmental factor during pregnancy is linked to higher risk of schizophrenia?

Exposure to influenza

When during pregnancy does influenza exposure pose the greatest schizophrenia risk?

Around the 2nd trimester (5–6 months in)

What does the threshold model of schizophrenia emphasize?

Illness occurs only when genetic and environmental risks exceed a certain level

What brain areas are smaller in some people with schizophrenia?

Hippocampus and amygdala

What is abnormal about hippocampal neurons in schizophrenia?

They are disorganized and misaligned

What is Reelin and its role in schizophrenia?

A protein that helps migrating neurons stop at the right place; it’s deficient in some patients

What is hypofrontality?

Underactivity of the frontal lobe seen in schizophrenia

What does accelerated loss of gray matter indicate in schizophrenia?

Early brain aging and neuron loss

What does the dopamine hypothesis of schizophrenia state?

It’s caused by excess dopamine or increased sensitivity to dopamine

What are neuroleptics and how do they work?

They are dopamine antagonists that block D2 receptors

How can amphetamines mimic schizophrenia symptoms?

By increasing dopamine levels

What is the link between L-dopa and psychosis?

L-dopa can increase dopamine and cause psychotic symptoms

What is the common target of all current antipsychotic medications?

Dopamine D2 receptors

What brain region has higher D2 levels in people with schizophrenia?

Auditory thalamus

What is one major issue with the dopamine hypothesis of schizophrenia?

Schizophrenics can have normal dopamine metabolite levels

Why is the dopamine hypothesis considered incomplete?

Not all symptoms respond to dopamine blockers and not all patients improve

Which symptoms of schizophrenia respond best to dopamine-blocking drugs?

Positive symptoms

What is an atypical neuroleptic drug?

An antipsychotic that blocks serotonin (5HT₂) and dopamine (D₂) receptors

What do atypical antipsychotics like Risperidone and Abilify do in the brain?

They block 5HT₂ and D₂ receptors, and may increase dopamine in the frontal cortex

Why might increasing dopamine in the frontal cortex be helpful?

It may reduce negative symptoms like apathy or slow speech

Do dopamine-blocking drugs help all schizophrenia symptoms?

No, they mostly help positive symptoms; negative and cognitive symptoms often remain

What neurotransmitter is now being targeted to improve cognitive and negative symptoms of schizophrenia?

Acetylcholine (ACh)

What are M4 PAMs used for in schizophrenia treatment?

They target positive symptoms by modulating dopamine activity

What do M1 PAMs aim to improve?

Cognitive symptoms (like attention and memory)

What do M5 NAMs help with?

Negative symptoms (like motivation and social withdrawal)

What is the glutamate hypothesis of schizophrenia?

Schizophrenia is due to underactivation of glutamate receptors

What receptor is targeted in the glutamate hypothesis?

NMDA receptor

How does PCP relate to schizophrenia?

It blocks NMDA receptors and can mimic schizophrenia symptoms

What happens to endocannabinoid (EC) levels in schizophrenia?

They are elevated in the cerebrospinal fluid (CSF)

What is the role of CB1 receptors in schizophrenia?

They inhibit neurotransmitter release and show increased binding in patients

What effect does THC have on schizophrenia?

It can trigger psychosis in at-risk individuals and worsen symptoms

What does the monoamine hypothesis propose about depression?

Depression is due to reduced synaptic activity of serotonin and norepinephrine

What does MAO do?

It breaks down monoamines like serotonin and norepinephrine

What do MAO inhibitors do?

They raise monoamine levels and improve depression

How does reserpine affect neurotransmitters?

It lowers monoamine levels and can cause depression

How do SSRIs like citalopram work?

They block reuptake of serotonin, increasing its availability in the synapse

What is the role of autoreceptors in depression?

Overactive autoreceptors reduce serotonin release

Why is there a delay in SSRI effectiveness?

Because autoreceptors must downregulate over time before serotonin release increases

What is the response rate to antidepressants in primary care?

About 60%

What does ECT do in the brain?

It raises monoamine levels, helping relieve depression

When is ECT used?

In severe or suicidal depression requiring fast symptom relief

What are the remission rates for ECT?

87% short-term, 43% long-term

What are three brain stimulation treatments for depression?

Fast TMS, deep brain stimulation, and vagus nerve stimulation

What area does deep brain stimulation target for depression relief?

Anterior cingulate gyrus and forebrain bundle

Why are SSRIs the first choice for antidepressant treatment?

They have fewer side effects and lower overdose risk

Do all antidepressants have equal effectiveness?

Yes, clinical studies show equal efficacy

What does the HPA axis do?

It controls the body's response to stress via cortisol

How is the HPA axis different in people with depression?

It is overactive and produces high levels of cortisol

What hormone is elevated in major depression?

Cortisol

What is the gut-brain axis?

The connection between gut microbiota and brain function

What systems are imbalanced in depression?

The immune system, HPA (stress) system, and gut microbiota

How does the vagus nerve relate to depression?

It connects the gut to the brain and plays a role in mood regulation

What are mania symptoms?

Excess energy, no need for sleep, risky behavior, grandiose thinking

What is cyclothymia?

Mild bipolar disorder with shifts between dysthymia and hypomania

What brain area acts like a mood switch in bipolar disorder?

Subgenual prefrontal cortex

What is panic disorder?

Sudden, repeated attacks of intense fear and physical symptoms

What is GAD (Generalized Anxiety Disorder)?

Chronic excessive worry about many things

What are obsessions in OCD?

Recurrent intrusive thoughts (e.g., germs)

What are compulsions in OCD?

Recurrent intrusive thoughts (e.g., germs)

What brain region is overactive in OCD?

Dorsolateral prefrontal cortex (DLPFC)

What treatments help OCD?

SSRIs, antipsychotics, and glutamate blockers

Which brain areas are overactive in OCD patients?

Orbitofrontal cortex and caudate nuclei (basal ganglia)

What happens to brain activity in OCD after behavioral therapy?

It decreases in overactive regions like the caudate nucleus

What surgical treatment can help severe OCD?

Disconnecting the orbitofrontal cortex from the anterior cingulate cortex

Which neurotransmitter is most linked to panic attacks?

Serotonin

What do the MRN and DRN nuclei in the raphe do?

MRN = regulates fear/anxiety; DRN = regulates cognitive/behavioral responses

How do benzodiazepines treat anxiety?

They bind to GABA receptors and enhance inhibitory action

What is commonly combined with benzodiazepines for anxiety self-medication?

Alcohol

What therapy works best for specific phobias?

Behavioral desensitization therapy

What is Tourette's syndrome?

Disorder of motor and vocal tics, with cognitive/behavioral deficits

What brain area shows increased activity during tics in Tourette’s syndrome?

Basal ganglia

What was the frontal lobotomy used for?

Treating psychiatric disorders by disconnecting the frontal lobes

How did Walter Freeman perform lobotomies?

Used electroshock for unconsciousness, inserted an ice pick through the eye socket, and moved it side to side

Who pioneered the frontal lobotomy procedure?

Walter Freeman

What was a major downside of frontal lobotomies?

Personality was severely affected despite some symptom relief

How long did the lobotomy procedure take?

3–4 minutes