Lecture 5: Cognitive Ability

Question 1

Intelligence

Answer 1

capacity to acquire and apply knowledge and skills

-conceptual variable that doesn’t rlly exist

Question 2

r of performance for an individual on different subjects and cognitive tests

Answer 2

r >0.3

- could be that the tests are all related in some way or that they all measure the same thing

Question 3

General intelligence theory (g)

Answer 3

suggests that there is a common element that contributes to all cognitive abilities
- math ability, perceptual ability, spatial ability, language ability, verbal comp, recall speed

Question 4

Are all cognitive abilities entirely driven by g?

Answer 4

No, g is not all that matters and correlation between any on cognitive ability is never perfect. A proportion of the variability in each ability must be explained by something else

Question 5

what do g and s mean in general intelligence theory

Answer 5

g is the cognitive engine that is shared by all abilities
s is the specific factor that is unique to a specific ability

AKA general and specific forces

Question 6

IQ test

Answer 6

most popular way to estimate g

- give individ many cognitive tasks (more than 10) and observe

Question 7

WAIS tests

Answer 7

Weschler Adult Intelligence Scale

• best reliability and validity
• includes: verbal comp index, working memory index, perceptual organization index, processing speed index

Question 8

Example of some cognitive tests

Answer 8

• picture completion
• block design
• raven’s progressive matrices

Question 9

Correlates of IQ

Answer 9

• pos correlated with longevity and height/weight
• negatively correlated with criminal behav and divorce rate
• pos correlated with income but not a good predictor of wealth

Question 10

Rmz and Rdz and h2 for IQ

Answer 10

MZ = 0.86 and DZ = 0.56 
h2 = 0.4 - 0.8

Question 11

Why does heritability of IQ increase with age?

Answer 11

• genes may affect our attraction to environments and our ability to benefit from them
• genes for IQ may take effect later on in life (innovation)
• and/or become increasingly important over time (amplification)

Question 12

Contribution of genetics to g

Answer 12

Genetic drive for g accounts for 58% of the total genetic variance
- majority of genetic variance for a cognitive ability is related to g

Question 13

Assortative mating

Answer 13

people mate in a way that is related to their phenotype

• positive AM: trait similarity between partners
• negative AM: trait differences (red hair)

Question 14

Large GWAs for intelligence

Answer 14

269k individ of european ancestry

• 1016 genes and 205 genomic loci associated with intelligence
• vast majority of genes strongly expressed in brain being partic enriched in spiny neurons and hippocampal cells
• GWAS hits used to create a polygenic score that predicted only 4% of intelligence

Question 15

Max amount of variability in intelligence that can be explained

Answer 15

4-10% using PS and GPS

Question 16

What are genes for intelligence doing?

Answer 16

• brain volume, development, cortical thickness, myelination, surface area?

Question 17

Cortical structure is highly correlated in

Answer 17

monozygotic twins partic in frontal lobe, sensorimotor strip and wernickes

Question 18

Transgenic mice overexpressing NMDARs have

Answer 18

better spatial memory than controls

Question 19

Issues with trying to find genes associated with intelligence

Answer 19

• need larger dataset
• many datasets dont use an intelligence test and if they do it isnt standardized
• educational attainment can be used as a proxy bc it is also heritable

Question 20

polygenic scores for Educational attainment predict… better than they predict…

Answer 20

• intelligence
• EA
  need intelligence for EA but dont always seek EA if you’re intelligent

Question 21

Flynn effect

Answer 21

suggests environment matters for IQ

• overall increase in IQ throughout the 1950s on to 2000s even tho the genes arent changing duh
• improved food, improved IT acesss, familiarity with testing, changes in home envs

Question 22

Genes and social economic status

Answer 22

positive correlation between SES and IQ, though direction is not obvious
- PS for educational attainment also predict social mobility

Question 23

Scarcity mentality

Answer 23

decline in IQ when times are rough

• scarcity (lack of resources) and being worried about scarcity may impair cognition
• poor cognition can in turn lead to further financial difficulties and stress (positive feedback)

Question 24

Genetic basis of cognitive disorders: PKU

Answer 24

No phenylalanine hydroxylase

- decreased NT levels (need dietary tyrosine)

Question 25

Genetic basis of cognitive disorders: down's syndrome

Answer 25

mild to moderate mental retardation - NDJ - risk increases with age of mother

Question 26

Genetic basis of cognitive disorders: fragile X syndrome

Answer 26

second most prevalent cause of mental retardation - problems with FMR1 gene in x chromosome - gene encodes for fragile x mental retardation protein (FMRP) important for normal development - triplet (CGC) repeat expansion in FMR1 gene (normal is 30 repeats and affected is 200 repeats) - mutations can occur in unaffected individuals in their lifetime which could be passed onto next gen (would not cause in the given person themselves)

Question 27

Is fragile x more common in males or females

Answer 27

hemizygous effect - twice as common in males because of x inactivation in females, so only 50% of females carrying the affected gene have FXS

Question 28

Genetic basis of cognitive disorders: Rett syndrome

Answer 28

Mutation in Xq28 on x chromosome - codes for methyl CpG binding protein 2 which is a very very important regulatory protein for mature nerve cells - part of silencing complex - only seen in females, need at least one copy of this gene (lethal in males)

Question 29

Genetic basis of cognitive disorders: AD

Answer 29

AD occurs in two forms: - early familial onset (30-65, pretty rare) - late onset AD (over 65) genetics more important in early onset - apolipoprotein E gene is only gene reliably associated with the disorder - identified genetic factors only explain a small proportion of cases of the disease.