Sickness behaviour

Question 1

Disorder

(Definition)

Answer 1

• Clinically significant distress or impairment
  
  • Distress/impairment is not good evidence of disorder
  • Impairment can be evidence of an adaptive trait (like in sickness behaviour)

Question 2

Congenital insensitivity to pain

(CIP)

Answer 2

• Extremely rare, heritable.
• Many die before 30 because of damage to their bodies
• Pain provides feedback from the environment that protects against injury

Question 3

Sickness Behaviour

(and some symptoms)

Answer 3

• Set of behavioural changes that develop when you are sick with infection
• Symptomology is very similar to depression:
  
  • Anhedonia, decrease in reproduction, eat less, fatigue, social withdraw, more sleep, inability to concentrate

Question 4

How is sickness behaviour produced

Answer 4

1. Increase in central proinflammatory cyotkines
   
   1. Interleukin 1B, Tumor Necrosis factor alpha (bacterial infections)
2. Peripheral cytokines produced by activated macophages
   
   1. Monocytes induce synthesis and release cytokines in the brain

Question 5

Energetic Cost of immune response

Answer 5

• Approximately a 30% increase in energy expenditure, very expensive
• Protein synthesis and protein catabolism increase, but body weight decreases in general

Question 6

Sickness behaviour tradeoffs

Answer 6

• In order to upregulate immune response, other areas need to have a decrease in metabolic expenditure to accomdate for that
  
  • This explains why there is a downregulation of reproduction, cognition, physical activity, social activity and growth/maintenance during this time

Question 7

Why do we eat less when we are sick?

Answer 7

• We want less protein more carbs
• Fat intake stays the same though
  
  • No fat because digestion of fats interfere with immune function.
  • Molecules involved in trasportation of lipids is used in immune response
• Why? Because foragine requies expending energy, especially hunting for protein. Because we are sick and metabolic costs of immune response are high, we downregulate physical activity

Question 8

Adamo et al

Food intake and disease resistance

Caterpillars

Answer 8

• Infected caterpillars with bacteria and force fed them different diets
• High lipid diet decreased survival
  *

Question 9

Milk Drinking vs. Fish eating

Answer 9

• Milk drinkers had way less fevers and infections
• Had less Serum FE and transferrin than fish eaters as well
• Reduction of iron decreases availabilty for growth, multiplicaiton of pathogens

Question 10

Sleep

Answer 10

• Brain is very active during sleep
• 20-25% of sleep is REM in 90 min cycles
  
  • Lightest sleep. Low amplitude, high frequency EEGs
• 75-80% = nREM
  
  • 4-stages. High amplitude, low frequency EEG, heaviest sleep

Question 11

Poor Sleep symptoms

Answer 11

• Obesity, Diabetes, hypertension, stroke, mental health complaints, poor cognition

Question 12

Sleep and Sickness

Answer 12

• Immune challenges alter sleep behaviour and immune functioning
• During sleep, body temperature drops
• REM decreases temp slightly due to decreased muscle tone
• Body maintains fever by fragmenting sleep by fragmenting NREM sleep cycle
  
  • And by decreasing REM all together

Question 13

Transferrin

Answer 13

• Transferrin is a protein secreted by the liver
• Higher in places with malignancy
• Transferrin finds iron and makes it unavilable to cells in that area so they can’t replicate