the science of depression

Question 1

biological symptoms of depression

Answer 1

• Poor sleep
• Poor appetite
• Reduced libido
• Poor concentration

Question 2

cognitive symptoms of depression

Answer 2

• Worthlessness (poor self esteem)
• Guilt
• Hopelessness
• Suicidal thoughts

Question 3

stress vulnerability model

Answer 3

• Our ‘vunerability’ can be genetic, or a result of early/prenatal experience
• Early experience sets our neuroendocrinological thermostat-epigenetics

Question 4

the HPA axis and depression

Answer 4

• Increased CRH (corticotropin-releasing hormone)
• Enlarged adrenals and pituitary
• Reduced -ve feedback
• Reduced GR (glucocorticoid receptor) ‘glucocorticoid resistance’

Question 5

role of early adversity and parenting

Answer 5

• History of childhood maltreatment (with or without current MDD) -> ↑ACTH release in response to stress
• Offspring of “high licking” lab rats show high GR expression (higher ACTH suppression)

Question 6

social rank affecting HPA function

Answer 6

Subordinate monkeys have:
• Heavier adrenal glands.
• Increased cortisol in hair
• Reduced dexamethasone suppression

Question 7

how does stress affect the brain?

Answer 7

• Neurotoxic
• Cause neuro-vulnerability
• Affect dendrite formation
• Reduces neurogenesis
• Cause changes to the EEG.
• Particularly affects the frontal lobes and hippocampus.

Question 8

frontal lobe role on emotion

Answer 8

Medial PFC:
•	Evaluating emotional state
•	Social cognition
•	Less volume loss
Dorsolateral PFC:
•	Working memory
•	Problem solving
•	Large volume loss

Question 9

the hippocampus role on emotion

Answer 9

• Reduced in size in MDD
• Dose related effect – correlated with number of and length of episodes
• Associates with learning based cognitive deficits
• Much of the volume loss is irreversible

Question 10

neurogenesis

Answer 10

• Grow axons and dendrites, and integrate into existing networks
• 6% of the total dendate gyrus population a month
• Restraint and shock stress causes reduced neurogenesis

Question 11

effect of stress on dendrites

Answer 11

• Mediated by reduced neurotrophins e.g. Brain derived neurotrophic factor (BDNF)
• Stress -> ↓BDNF (animals) - Reversed with antidepressants
• Low BDNF in unmedicated depressives - Normal to high in medicated patients
• The lowest levels in post-mortems of successful suicide victims.

Question 12

how do antidepressants work?

Answer 12

• Antidepressants increase GR expression (regulating HPA activity)
• Antidepressants increase neurogenesis
• They increase BDNF synthesis. ∴ improve connectivity and increase number of synapses

Question 13

freud model

Answer 13

super-ego (morals/rules) vs Id (needs wishes)

Question 14

modern scanning techniques

Answer 14

• Based on oxygen or glucose take up.
• Much improved from “if it light up it’s active”
• Functional connectivity (from the mid 90s) Functional connectivity- Spatially distinct areas of the brain showing similar activity at similar times
• Allows the study of networks.

Question 15

default mode network

Answer 15

•	It’s what comes on when there’s nothing to do (“resting state”)
Autobiographical details
•	The self’s place in time and space
•	Projecting to other places in time and space
Self reference
•	Referring to traits or states
•	Emotional and moral reasoning
Thinking about others
•	Theory of mind
•	Social judgements/evaluations

Question 16

DMN in depression

Answer 16

• Depressed people find it hard to appropriately switch off their DMN in response to a task.
• We already knew depressed people excessively ruminate.

Question 17

entropy

Answer 17

• The brain attempts to reduce entropy
• It does this by making predictions. making predictions.
• Called top-down processing. down processing.
• Initially visual predictions, and other basic sensory functions.
• Eventually words, concepts, core beliefs. core beliefs. - eg. “I am fat/stupid

Question 18

mindfulness and medication

Answer 18

• Short (8 week) course of daily mindfulness practice reduces activity in the DMN reduces activity in the DMN1
• AND, treats and prevents MDD! AND,
• Focussing on the breath – increasing attention
• Being more aware of one’s own mind

Question 19

is modern society depressogenic?

Answer 19

• Over-emphasis on the self, and one’s ‘rank’
• Self-referential ruminations
• Fear of social threat

Question 20

5 pillars of wellbeing

Answer 20

• Physical activity
• Connect with others
• Learn something new
• Practice mindfulness
• Acts of generosity