ch 18 psychiatric disorders

Ch 18 Psychiatric Disorders

Psychiatric Disorders

Disorders of psychological function sufficiently severe to require treatment

Diagnosis can be difficult Patients with the same disorder can display different

symptoms Patients with different disorders can display many of

the same symptomsDiagnosis based on info from the DSM

(Diagnostic & Statistical Manual of the American Psychiatric Association)

Psychiatric Disorders

SchizophreniaAffective Disorders: Depression & ManiaAnxiety DisordersTourette Syndrome

Schizophrenia

Means “splitting of psychic functions”The disorder most commonly associated with

madnessAffects 1% of the populationTypically begins in adolescence or early

adulthoodComplex & diverse symptoms that overlap with

those of other disordersSymptoms frequently change during

progression of the disorderNo single symptom appears in all cases

Schizophrenia

Symptoms split into 2 categories:1. Positive:

Symptoms that seem to represent an excess or distortion of normal function

2. Negative: Symptoms that seem to represent a reduction or

loss of normal function

Positive Symptoms of Schizophrenia

Delusions Delusions of being controlled, persecution, or grandeur

Hallucinations Imaginary voices making critical comments or telling the

individual what to doInappropriate affect

Failure to react with the appropriate emotion to eventsIncoherent speech or thought

Illogical thinking, echolalia (vocalized repetition of some or all of what was heard), peculiar associations among ideas, belief in supernatural forces

Odd behavior Difficulty performing everyday tasks, lack of personal hygiene,

talking in rhymes, catatonia (remaining motionless, often in awkward positions)

Negative Symptoms of Schizophrenia

Affective flattening Reduction or absence of emotional expression

Alogia Reduction of absence of speech

Avolition Reduction or absence of motivation

Anhedonia Inability to experience pleasure

Causal Factors in Schizophrenia

Genetic componentBut experience also plays a roleSome people inherit a potential for the

disorder & it may or may not be activated based on experience

Factors that can contribute to the development of schizophrenia Birth complications, early infections, autoimmune

reactions, toxins, traumatic injury & stress

Dopamine Theory of Schizophrenia

First suggested by the fact that early antipsychotic drugs (chlopromazine & reserpine) caused motor effects like those of Parkinson’s

Theory that schizophrenia is caused by the presence of too much dopamine

Amphetamine & cocaine, which increase dopamine, can cause schizophrenic episodes in healthy people

Dopamine Theory of Schizophrenia

Discovery that there are 5 subtypes of dopamine receptors (D1-D5)

Drugs worked in different ways because they acted on different receptor subtypes

Schizophrenia is caused by hyperactivity specifically at D2 receptors Widely accepted, but still doesn’t explain the whole

pictureNeuroleptics: antischizophrenic drugs

Higher affinity for D2 correlates to effectiveness

Limitations of the Dopamine Theory

4 key discoveries that cannot by explained by the D2 version of the theory:

1. Receptors other than D2 are involved Glutamate, GABA & 5-HT Atypical neuroleptics developed to act on these

non-D2 receptors (ex: clozapine)

2. It takes weeks of neuroleptic therapy to alleviate symptoms

Despite the fact that neuroleptics can block activity at D2 receptors within hours

Limitations of the Dopamine Theory

3. Schizophrenia is associated with widespread brain damage

Not just limited to dopaminergic circuits

4. Neuroleptics are only marginally effective Not effective in all cases When they do have an effect, it is generally only on

some of the symptoms More effective in treating the positive symptoms

Affective Disorders: Depression & Mania

Affective Disorders: Any psychiatric disorder characterized by disturbances of mood or emotion Aka mood disorders

Depression

Experiencing periodic depression is a normal reaction to loss

However, some people have an increased tendency toward depression They repeatedly fall into deep despair & experience

anhedonia (inability to experience pleasure), often for no apparent reason

Depression

Depression can be so extreme that it is almost impossible for them to complete necessary daily tasks (keep a job, relationships, eating, personal hygiene)

Often have sleep issues & thoughts of suicide

When this condition lasts over 2 weeks, it is classified as clinical depression or major depressive disorder

Mania

Mania: Characterized by overconfidence, impulsivity, distractibility & high energy Generally the opposite of depression

During mild mania: Talkative, energetic, impulsive, positive & very confident Can be great at a job and/or very fun

Full-blown mania: Unbridled enthusiasm, incessant talking that jumps

topics, grandiosity, high energy, distractability, impulsiveness

Often leads to disaster, failed relationships, unfinished projects

Major Categories of Affective Disorders

Bipolar affective disorder: Depressive patients who experience periods of mania

Unipolar affective disorder: Depressive patients who do not experience mania

Reactive depression: Depression triggered by a negative experience (a

death, job loss)Endogenous depression:

Depression with no apparent cause

Probability of suffering from clinical depression during a lifetime is 10%

Women 2x more unipolar affective disorder than men (bipolar equal)

Risk of suicide in clinically depressed individuals is 5%

Affects all agesAffective disorders associate with heart

disease And bone loss in women

Causal Factors in Affective Disorders

Genetic factorsSeasonal affective disorder (SAD):

Attacks of depression & lethargy recur every winter Triggered by reduction of sunlight Light therapy can reduce symptoms

Postpartum depression: Depression experienced by some women after giving

birth

Antidepressant Drugs

4 major classes of drugs for the treatment of affective disorders:

1. Monoamine oxidase inhibitors2. Tricyclic antidepressants3. Selective monoamine-reuptake inhibitors4. Mood stabilizers

Monoamine Oxidase Inhibitors (MAOIs)

Monoamine agonist that increases the levels of monoamines by inhibiting the activity of monoamine oxidase (MAO), the enzyme that breaks down monoamine NTs

MAO inhibitors have several side effects, including the cheese effect Consuming foods high in tyramine

(cheese, wine, pickles) have risk of stroke from surges in blood pressure

Tricyclic Antidepressants

Named for the 3 rings of their chemical structure

Work by blocking the reuptake of serotonin & norepinephrine

Safer than MAOIs

Selective Monoamine-Reuptake Inhibitors

Selective serotonin-reuptake inhibitors (SSRIs): Serotonin agonists that block the reuptake of serotonin from

the synapse Prozac, Paxil, Zoloft, etc. Few side effects Act against a wide range of psychological

disorders in addition to depression

Selective norepinephrine-reuptake inhibitors (SNRIs)

Mood Stabilizers

Developed because other antidepressants often triggered mania

Mechanism of action is unknownEx: Lithium (a metallic ion)

Brain Pathology & Affective Disorders

MRI studies have shown reductions in overall brain size & in many different brain structures in bipolar patients However, lots of variation

2 structures are often abnormal: Amygdala Anterior cingulate cortex (and often the connections between them)

Monoamine Theory of Depression

Depression is associated with underactivity at serotonergic & noradrenergic synapses

Largely based on the fact that many of the drugs found to alleviate depression work as agonists of 5-HT, NE or both

Up-regulation: A compensatory increase in # of receptors for a NT when there is an insufficient amount of that NT released at a synapse Autopsies of clinically depressed individuals often

have more 5-HT & NE receptors than normal

Diathesis-Stress Model of Depression

Some people inherit a diathesis (genetic susceptibility) & stress exposure in early life causes them to be permanently sensitized, causing them to overreact to mild stressors for the rest of their lives The diathesis alone cannot initiate the disorder

Indirect evidence Depressed individuals release more stress hormones

Treatment of Depression with Brain Stimulation

Significant therapeutic effects of chronic brain stimulation through an implanted electrode

Stimulates the anterior cingulate gyrusPermanently embedded under the skin to

give continual pulsesExtreme measure given to those who do not

respond to conventional treatments

Anxiety Disorders

Anxiety: Chronic fear that persists in the absence of any direct threat Psychological correlate of stress Adaptive when it motivates effective coping behaviors Maladaptive when it is so severe it disrupts normal

functioning (anxiety disorders)Anxiolytic: anxiety reducingAnxiogenic: anxiety provoking

Anxiety Disorders

All anxiety disorders associated with feelings of anxiety (fear, worry, despondency) & variety of physiological stress reactions (tachycardia, hypertension, nausea, breathing difficulty, sleep disturbances, high glucocorticoid levels)

Most prevalent psychiatric disorder17% of people have one at some point in their

lives Women 2x

5 Classes of Anxiety Disorders

1. Generalized Anxiety Disorders: Characterized by stress responses & extreme feelings of

anxiety that occur in the absence of any obvious reason

2. Phobic Anxiety Disorders: Similar to GAD but triggered by a specific object (ex:

spiders, dogs) or situation (ex: flying, darkness) Agoraphobia: pathological fear of public places & open

spaces

3. Panic Disorders: Characterized by rapid-onset attacks of extreme fear &

severe symptoms of stress (choking, heart palpitations, shortness of breath)

5 Classes of Anxiety Disorders

4. Obsessive-Compulsive Disorders: Characterized by frequently recurring,

uncontrollable, anxiety-provoking thoughts (obsessions) & impulses (compulsions)

The compulsive behavior is done to alleviate the anxiety associated with the obsessions

5. Posttraumatic Stress Disorder: Persistent pattern of psychological distress

following exposure to extreme stress (ex: war, sexual assault)

Etiology of Anxiety Disorders

Genetic componentLarge experiential component

Because the anxiety often has an identifiable trigger, it is easier to assess the influence of experience in these types of disorders

Pharmacological Treatment of Anxiety Disorders

3 categories of drugs1. Benzodiazepines

Most widely prescribed psychoactive drugs Ex: Valium Several adverse side effects Highly addictive; so only for short-term use Thought to work by agonizing GABA receptors

2. Serotonin Agonists Advantage of specificity; doesn’t cause the side effects

associated with benzos But does have its own side effects

3. Antidepressant Drugs Common comorbidity (tendency to occur together in the same

individual) of depression & anxiety

Neural Bases of Anxiety Disorders

Substantial overlap in brain areas involved in anxiety & affective disorders Amygdala, anterior cingulate cortex But with anxiety disorders, there is no gross damage

(as opposed to shrinkage with affective) Increased activity in the amygdala of a phobic patient

when shown a picture of ex: a spider

Tourette Syndrome

A disorder of tics Involuntary, repetitive, stereotyped movements of vocalizations

Many people with this disorder have no symptoms other than tics

Typically begins in childhood with simple motor tics (blinking), with symptoms growing more complex & severe with age (hitting, hopping, lewd gestures)

Verbal tics can include barking, grunting, cursing (coprolalia), echolalia

Symptoms usually reach a peak after a few years & often subside as the patient matures

Tourette Syndrome

0.7% of the population 3x more frequent in males

Major genetic componentSome patients also have ADD/ADHD and/or

OCDAlthough tics are involuntary, they can be

temporarily be suppressed with great effort from the patient

Neuropathology of Tourette Syndrome

Very difficult to studyPeople with this disorder often have smaller

caudate nucleiSome evidence of thinning in sensorimotor

cortex areas that control the face, mouth & voice box

Treatment of Tourette Syndrome

Tics usually treated with neuroleptics Can reduce tics by about 70% However, often patients won’t take them because of

the adverse side effects