Final - Psychopathology Flashcards
Schizophrenia
Statistics
Afflicts ~ 0.8% of the population.
Age of onset ~ 19.2 years
Positive Symptoms of Schizophrenia
- Hallucinations
- Delusions
Hallucinations
Positive symptom of schizophrenia.
- Auditory (hearing things that aren’t really there) is the most common, followed by somatosensory (e.g., bugs crawling on skin) and olfactory.
- Visual hallucinations are rare.
Delusions
- A fixed false belief.
- Grandeur
- Paranoid (“out to get me”)
- Religiousity
Religiousity and paranoia make SZ very hard to treat because patients won’t trust advice.
Negative Symptoms of Schizophrenia
Negative symptoms are the first to appear but are hard to recognize.
- Flat affect
- Anhedonia (inability to experience joy)
- Social withdrawal
Theories of Schizophrenia
- Genetic
- Dopamine
- Seasonality/2nd Trimester Hypothesis
- Brain Damage/Abnormalities
MZ twins are _______ times as likely to be concordant for SZ than DZ twins.
4
MZ Twin
“Identical.”
One egg travels down falopian tube and upon fertilization, splits into 2.
Twins from the same egg are therefore 100% genetically identical.
DZ Twin
“Fraternal.”
2 eggs travel down falopian tube and are fertilized.
Share 50% genetic similarity (same amount as a normal sibling).
What are the rates of SZ for a child of a SZ parent and a child of the non-SZ parent who have MZ twin grandparents who are concordant for SZ?
- Offspring of parent with SZ = 16.8% have SZ
- Offspring of non-SZ parent = 17.2% have SZ
BOTTOM LINE = You’re just as likely to be SZ if your MZ twin grandparents both have SZ regardless of whether your parent had SZ.
SZ Candidate Gene
DISC-1
(Disrupted in Schizophrenia 1)
DISC-1
- Gene that codes for a protein that is involved in neurite outgrowth and neuronal growth.
- The DISC-1 aberration was present in a family with a high incidence of SZ.
- If take neuronal cells and grow them in a dish and knock-out the DISC-1 proten, the neurons won’t spread their “arms”.
Support for the Dopamine Hypothesis of SZ
- If you block D2 receptors, the positive symptoms of SZ will be decreased.
* Thorzine, Haldol (anti-psychotics) - If you give a DA agonist to a SZ, their symptoms will become much worse.
* E.g., amphetamine, cocaine - DA agonists can mimic the SX of SZ in normal, healthy human populations.
* In a 1972 experiment, experimenters gave 10mg of meth round the clock for 5 days straight to normal volunteers. Had to stop study early b/c participants had full-blown SZ-like symptoms.
Meth Use for _______ days straight invokes SZ like positive symptoms
3
DA Pathways
- Nigrostriatal Pathway [SN–>Striatum (part of basal ganglia that has to do with movement)]
- Mesolimbic Pathway/Median Forebrain Bundle (MFB) [VTA–>Limbic System (NaC, Amygdala, Anterior cingulate)].
The MFB is implicated in SZ and can view positive symptoms as dysfunction of emotion/limbic system.
NaC
Pleasure/Reinforcement
Bottom of frontal lobe above lateral sulcus
Amygdala
Fear, Anger (paranoia)
Temporal lobe
Anterior Cingulate
Plays a key role in thought processes and how emotions drive behavior.
Above CC.
4 Characteristics of Atypical Antipsychotics
&
An Example
- Block D4 receptors instead of D2 receptors.
- No EPS (“extrapyramidal symptoms”) (movement problems)
- Capable of treating patients who are “treatment refractory” (= failed on at least 3 typical anti-psychotics).
- Help alleviate negative symptoms.
Ex. Clozapine
DA Receptors & Antipsychotics
DA receptors range from D1-D5.
- Striatum = Primarily D2 receptors
- Haldol, Thorazine
- Parkinsonian-Like Symptoms
- Limbic System = Primarily D4 receptors (want to block these receptors to mitigate positive symptoms). No parkinsonian-like symptoms.
- Clozapine
- Must get weekly blood tests to monitor WBC count (some ppl will develop agranuloytosis (no immune cells)
- Clozapine
Seasonality/2nd Trimester Hypothesis of SZ
Based on fact that a majority of SZs are born in the Spring. Mother would be in the height of the flu season in 2nd trimester.
Neurodevelopment During 2nd Trimester
Neural stem cells are (1) proliferating, (2) migrating and (3) differentiating.
If a flu virus disrupts this process, a “disorganized pattern later results in disorganized thoughts.” If examine the brains of SZs, there won’t be neatly formed layers because as the neural stem cells climb the radial glia guide cells, they get stuck and the traffic jam will result in cells jumping off at whatever layer they can.
Hypofrontality & SZ
Hypofrontality is decreased function in the frontal lobe. SZs typically exhibit hypofrontality and have difficulty with sorting tasks and switching tasks/gears.
Ex. Wisconsin Card Sorting Test, Raven’s Progressive Matrices/Patterns Test.
MZ Twin Study: SZ Rates in MZ Twins That Are Monochorionic vs Dichorionic
- Monochorionic = Share placental sack
- 60% concordant for SZ
- Dichorionic = Individual placental sacks
- 17% concordant for SZ
Some viruses may only pass through one placental sack.
Brain Damage/Abnormalities in SZ
- Enlarged Ventricles
- Hypofrontality
- Don’t have too much DA.
Enlarged Ventricles & Schizophrenia
- Enlarged ventricles can be caused by a shrinking of the structures next to the ventricles (e.g., brain tissue, caudate, cingulate gyrus, hippocampus).
- Enlarged ventricles can also be caused by hydrocephaly (fluid on brain). If have too much CSF, the structures of the brain can start separating.
Do SZs have too much DA?
NO.
Studies show that they have too many receptors byt it’s hard to believe these studies because they’re usually done on SZs who have taken anti-psychotics already (which can cause receptors to up-regulate or down-regulate).
