LC 2 - cognitive development and ageing

Question 1

brain development over a lifetime

Answer 1

• Neurons are at max after birth
  o Loss of neurons is not very great
  o Neurons seem to shrink with age
• Synapses decline steeply  synaptic pruning
  o Optimization of networks
• Grey matter matures (increase of thickness) with age
  o Primary cortices  S1 and M1 ripen first (also V1 and auditory, etc)
  o Cognitive regions ripen later
• Connectivity changes with age (it decreases)

Question 2

cognitive functions

Answer 2

• Cognitive functions = Mental activity between sensory input & motor output
• Mediated by neocortical brain structures
• Neuropsychological definition:
  o Intelligence
  o Attention Learning and memory
  o Problem solving / executive function
  o Language ability
  o Visuo-spatial ability Sensorimotor function (…)
  o Memory (medial temporal lobe)
• Important for daily functioning
• Unitary or compound?
  o Cognition is not unitary but can be tested that way (MMSE)

Question 3

development of cognition

Answer 3

• Driven by brain plasticity  interaction with environment is crucial
• Sequential timing of domain functions development
  o Attentional control
  o Information processing (basic)
  o Cognitive flexibility
  o Goal setting
• Prefrontal cortex is essential for cognitive functions
• Pivotal role of attentional control (develops first)

Question 4

ageing patterns

Answer 4

• Word fluency is least affected by age
• Letter copying is more effected –> performance based outcomes (speed based)
• Control processes (processing new info) increase until maturity (mid-age) and decrease very hard at older age
  o Seems linear but is slightly quadratic
  o Variance in performance increases with age
• Not all processes decline after maturity language can stay stable or even increase with older age

Question 5

brain plasticity over time

Answer 5

• The ability of the neuronal tissue to adapt to its environment
• Decreases vastly after infancy
• Gene expression and connectivity change with time –> deregulate

Question 6

ageing mechanisms

Answer 6

• Vascular ageing
• Oxidative stress
• Hormonal dysregulation
• Telomere attrition (not as important for brain since most cells do not divide except some stem cells – also found around the ventricles)
• Immunosenescence

Question 7

brain ageing

Answer 7

• Overall shrinkage (anterior / posterior gradient; grey > white matter)
• Loss in connectivity (white matter)
• Dopamine depletion
• Due to:
  o (micro-) vascular changes (hypertension)
  o changes in signalling pathways (e.g. insulin/IGF-1)
  o oxidative stress
  o recurrent / chronic inflammation
  o stress-related corticoid levels

Question 8

overall health and cognition

Answer 8

• Brain depends on multiple organ systems for O2, glucose and nutrient supply
• Sensitive to metabolic disturbances
• Many diseases & pharmacological therapies have impact on brain function
• “Brain stressors”
  o Hypertension
  o CVDs
  o Obstructive pulmonary disease (asthma)
  o Renal failure
  o Liver failure
  o Cancer
  o Thyroid dysfunction
  o Endocrine disorders

Question 9

ageing, health and cognition

Answer 9

• Increase of variance in cognitive domains: ‘health-related vulnerability factors’?
• E.g., head trauma, vascular disease, life style, health
• Concept of ‘Brain reserve capacity’ (BRC)
  o CNS redundancy  overcapacity  compensate for losses
  o Proxy measures: e.g. brain size, cortical surface area
• Age reduces BRC
• Lower BRC related to dementia risk
• LIBRA score measures the dementia risk as a function of lifestyle factors
• With age networks are reorganised to compensate for reduced BRC – often the other hemisphere will be used to complement the hemisphere that is used in young people
  o This only works to a certain age, after 70 the compensation does not cover the pathological changes anymore

Question 10

vascular risk

Answer 10

• Vascular dysfunction (due to vascular risks like hypertension, diabetes, inactivity) leads to diffuse white matter lesions –> mild cognitive impairment –> (vascular) dementia
  o More lesions –> higher dementia risk
• Cognitive decline varies between the types of dementia
  o AD= slow and constant decline
  o Vascular= sudden changes that are irregular