Behavioral Science - Genetics in Psychiatry - Thomas L. Schwartz Flashcards Preview

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Flashcards in Behavioral Science - Genetics in Psychiatry - Thomas L. Schwartz Deck (62)
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1
Q

T/F – Genetics of most hereditary disorders (70 % inheritance) can be mapped to specific genes

A

False.
require hundreds of mutated genes to produce spectrum of clinical symptoms that would cause someone to meet diagnostic criteria for specific disorder

2
Q
High or low genetic heritability? 
ADHD? 
Depression? 
Anxiety? 
Schizophenia?
A

ADHD? - HIGH
Depression - LOW
Anxiety - LOW
Schizophenia - HIGH

3
Q

Epistasis describes ___

A

the effect of one gene being dependent on the presence of one or more ‘modifier genes’

4
Q

What are epigenetics? Does it involve changes in DNA?

A

describes change in gene expression due to environmental influences, NOT change DNA

5
Q

Nigrostriatal dopamine pathway:
Originates ___ projects to ____
Controls ___

A

Originates at substantia nigra
Projects to striatum/basal ganglia
Controls motor function and movement

6
Q

Mesolimbic dopamine pathway:
Originates ___ projects to ____
Controls ___

A

Originates at VTA of midbrain
Projects to nucleus accumbens
Controls reward and perception of pleasurable sensations, delusions and hallucinations of psychosis

7
Q

Mesocortical dopamine pathway:
Originates ___ projects to ____
Controls ___

A

Originates at VTA of midbrain
Projects to DLPFC or VMPFC
Controls executive functions
VTA > DLPFC Controls cognitive symptoms of schizo
VTA > VMPFC controls affective symptoms of schizo

8
Q

Tuberoinfundibular dopamine pathway:
Originates ___ projects to ____
Controls ___

A

Originates at hypothalamus
Projects to anterior pituitary
Controls prolactin secretion

9
Q

Tuberoinfandibular DA pathway
hypofunction?
hyperfunction?

A

hypofunction? hyperprolactinemia

hyperfunction? hypoprolactinemia

10
Q

Mesolimbic dopamine pathway:
hypofunction?
hyperfunction?

A

hypofunction? amotivation, apathy

hyperfunction? addiction, hallucinations

11
Q

Nigrostriatal dopamine pathway:
hypofunction?
hyperfunction?

A

hypofunction? dyskinetic movement, parkinsonism

hyperfunction? dyskinetic movement

12
Q

Mesocortical dopamine pathway:
hypofunction?
hyperfunction?

A

hypofunction? inattention

hyperfunction? hypervigilance, insomnia

13
Q

Which dopamine pathways are involved in schizophrenia? Which are hypoactive which are hyperactive?

A

Mesolimbic - hyperactive

Mesocortical - hypoactive

14
Q

What could a mutation in COMT cause?

A

Schizophrenia ** if paired with other mutations

COMT is catachol-O-methyl transferase > degrades DA mutation usually generates high levels of DA

15
Q

What are 4 genes involved in dopamine pathways that could lead to schizophrenia symptoms if many mutations occur?

A

COMT
Tyrosine hydroxylase
D2R (dopamine receptor 2 - sometimes called DAR2)
D3R

16
Q

What does DISC1 do?
Mutation of DISC1 is associated with what disease?
What is the MAO

A

DISC1 normally facilitates neurogenesis, cell migration, differentiation, synaptogenesiss and selective pruning of synapses

schizophrenia

epistatic mutation - multiple other downstream genes are affected

17
Q

What are 2 genes that DISC1 mutation can affect?

A

ErbB4, NRG

18
Q

Mutation of DISC1 is associated with what disease?

What is the MAO

A

schizophrenia

epistatic mutation - multiple other downstream genes are affected

19
Q

T/F it is possible to have normal dopamine levels and still have schizophrenia

A

True

Can be due to disrupted neurodevelopment that doesn’t affect dopamine

20
Q

characteristic brain activity patterns on fMRI associated with gene activation/deactivation/mutation

A

endophenotype

21
Q

What is one plausible explanations for mesocortical hypoactivity and mesolimbic hyperactivity?

A

dysfunctional PFC results in loss of top down control of limbic DA release

22
Q

Hyperactive mesolimbic system is associated with mutations in which genes?

A

D2R, Tyrosine hydroxylase, MAOs

23
Q

Hypoactive mesocortical system is associated with mutations in which genes?

A

COMT and D3R

24
Q

What are 2 genes involved in ADHD

A

D4R, D5R

25
Q

If enough ADHD associated mutations occur what could occur?

A

schizophrenia symptoms

26
Q

5 gene mutations involved in ADHD?

A
DRD1 (DRD = DAR = D1R)
DRD2 
DRD4 
DAT1
DISC1 (also schizo)
27
Q

In ADHD what brain regions are affected? Hyper vs Hypo active?

A

Anterior cingulate cortex and mesocortical pathway is hypoactive

other cortical regions (e.g. insula) not associated with vigilance and concentration are hyperactive - (inefficient compensation)

28
Q

what two genes are implicated in mesocortical and anterior cingulate hypofunction in ADHD?

A

DRD4 DRD5

29
Q

In Depression which pathways/brain regions are involved

A

mesocortical system is primarily involved
DLPFC is hypoactive
VMPFC between right and left hemispheres (emotional processing areas) are hyperactive

limbic regions are also hyperactive

30
Q

What genes are involved in major depressive disorder?

A

DAT, DRD4, COMT

could result in schizo if too many mutations develop

31
Q

In major depressive disorder - hypoactivity in DLPFC is linked to _____

Hyperactivity in VMPCF and limbic areas are linked to ____

A

Poor DA tone

Serotonin mutations

32
Q

Inheritance of which 3 genes might contribute to hypoactivity of the DLPFC / disfunction of the mesocortical pathway in major depressive disorder?

A

COMT, DAR4, DAT

dysfunctional VTA is responsible for hypoactivity of DLPFC (ventral tegmental area of the midbrain –> origin of mesocortical DA pathway)

33
Q

What is the precursor to serotonin?

A

tryptophan

34
Q

True or false, the 5HT pump can also pump in tryptophan

A

False - serotonin and tryptophan pumps are distinct

35
Q

Put these in sequence: TRY-OH, serotonin, VMAT2, AAADC, tryptophan, 5HTP

What pathway is this?

A

Tryptophan>TRY-OH>5HTP>AAADC>5HT (serotonin)>VMAT2

Serotonin synthesis:
Tryptophan is pumped into cell via tryptophan specific transporter then converted to 5HTP by tryptophan hydroxylase (TRY-OH; aka TPH), which is then converted to serotonin/5HT by AAADC and packaged in vesicles by vesicle monoamine transferase 2 (VMAT2)

36
Q

T/F serotonin can be brought back into the serotenergic axon terminal via SERT

A

true

SERT = serotonin reuptake transporter

37
Q

T/F low levels of intracellular serotonin/5HT can be broken down by MAO-A

A

False - HIGH (not low) levels of intracellular serotonin can be broken down by MAO-B (not A)

38
Q

T/F extracellular serotonin can be broken down by COMT

A

False - this beaks down DA

39
Q

Extracellular serotonin can be broken down by ___?

A

MAO A and/or MAO B

40
Q

T/F serotonergic projections originate in the locus cereleous?

A

False - Serotonin projections originate in the Raphe Nucleus

41
Q

T/F serotonin projections are both ascending (into the brain) and descending (down the spinal cord)?

A

True - NE projections from LC do the same

42
Q

What do the descending serotonin pathways do?

A

regulate pain (descending inhibitory system)

43
Q
Hyperfunctioning lymbic serotonin pathways cause these symptoms:
1
2
3
4
A

Panic
Worry
Obsession
Depression

44
Q

T/F hyperfunctioning lymbic pathways have high levels of SE

A

False - may have poor serotonin acitvity

45
Q

What are 3 commonly mutated genes involved in the serotonin Genetics of MDD/Anxiety/Eating Disorder/BPDO?

A

5-HT2A 102 T/C
5-HTTLPR promoter
TPH (tryptophan hydroxylase)

46
Q

5-HTTLPR promoter regulates the expression of the 5-HTTLPR gene. What does the 5-HTTLPR gene code for?

A

SERT

47
Q

In depression/anxiety the cingulate cortex and amygdala are hypoactive of hyperactive? What NT is throught to be responsible

A

Hyperactive

Poor serotonin tone

48
Q

in anxiety and depression the mesolimbic system is hyper of hypoactive?

A

hyperactive - also the medial frontal cortex

49
Q

Which serotenergic gene mutations cause hyperactivity of the mesolimbic system and medial frontal cortex in anxiety/depression?

A

5HT2R, 5HTTLRP, TPH

Serotonin 2 receptor, CERT, tyrosine hydroxylase

50
Q

5HT2R, 5HTTLRP, TPH mutations in axiety and depression result in increased or decreased firing and reactivity of the Raphe nucleus?

A

Increased reactivity and firing - don’t really understand this.. less serortonin reaches the

51
Q

Put these in order: NE, Tyrosine, VMAT2, DOPA, DDC, TOH, DBH, DA

A

Tyrosine> (TOH) tyrosine hydroxylase>DOPA>(DDC) dopamine decarboxylase>DA>(DBH) dopamine beta hydroxylase>NE>VMAT2

52
Q

Hyperfunctioning lymbic NE pathways cause these symptoms:
1
2
3

A

Panic
worry
arousal

NE might be too high! (opposite of serotonin)

53
Q

Hypofunctioning corticofrontal NE pathways cause these symptoms:
1
2

A

ADHD

Depression

54
Q

What does hypofunctioning of DA NE pathways cause

A

loss of possitive emotion/affect

55
Q

depressed mood; loss of happiness, interest, or pleasure; loss of energy or enthusiasm; decreased alertness; and decreased self-confidence are associated with hypofunctioning of which NT systems? Increase in negative affect or loss of positive affect?

A

DA + NE hypofunction

Loss of positive affect

56
Q

depressed mood, guilt, disgust, fear, anxiety, hostility, irritability, and loneliness

associated with hypofunctioning of which NT systems? Increase in negative affect or loss of positive affect?

A

SE (sometimes NE)

Increase in negative affect

57
Q

What symptoms are associated with an decrease in positive affect?

A

depressed mood; loss of happiness, interest, or pleasure; loss of energy or enthusiasm; decreased alertness; and decreased self-confidence

58
Q

What symptoms are associated with an increase in positive affect?

A

depressed mood, guilt, disgust, fear, anxiety, hostility, irritability, and loneliness

59
Q

Do PTSD patients have increased or decreased negative or positive affect?

A

Increased negative affect

60
Q

What is the difference between Met vs Val alleles of COMT?

A

Met-COMT = low function/monoamine degradation so high NE/DA = increased NE/DA and anxiety in limbic areas

VAL–COMT = high function = low NE/DA in cortex (in depression VAL allele of COMT could explain low concentration of NE and symptoms of low energy.poor concentration)

61
Q

X inactivation of MAO results in what?

A

two copies of MAO expressed - Faster degradation of monoamines and lower levels available to cortex = depression in females

62
Q

ADHD is associated with what mutation? How does this affect neurotransmitter levels? What brain regions are affected? Hypo or hyper active?

A

COMT Val allele results in increased monoamine breakdown (so less NT) depriving the frontal cortex and cigulate cortex making them hypoactive

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