Depression Flashcards
Biological symptoms of depression
- poor sleep
- poor appeptite
In depr
- cortisol binds back to receptors which switch off the ongoing production of cortisol. So youre response is diminished. However in depression there is increased cortisol
Depression
- more cortisol
- enlarged adrenals and pituitary
- reduced negative feedback
- reduced GR expression: glucocorticoid resistance
How does this link to depression
history of childhood maltreatment
- increased ACTH release in response to stress
Other thigns that affect HPA function
1.) Social rank: subordinate monkeys have heavoer adrenal glands/increased cortisol in hair
How does stress affect the brain
- Steroids are:
1. ) neurotozic
2. ) cause neuro-vulnerability
3. ) Affect dendrite formation
4. ) Reduces neurogenesis - affects frontal lobes and hippocampus
How are the frontal lobes
- ) Medial pre frontal cortex
2. ) Dorsolateral pre-frontal cortex
Medial PFC
- evaluating emotional state
- social cognition
- less volume loss
Dorsolateral PFC
- working memory
- problem solving
- large volume loss
The hippocampus
- important for memory
- bilateral lesions: complete anterograde memory loss
How is the hippocampus affected
- reduced in size in MDD
What does stress do
It down regulates neurogenesis
What causes reduced neurogeneis
- restraint and shock stress
What else does stress affect
Dendrites
Stress
0 Mediated by reduced neurotrophins e.g. BDNF
What is BDNF
- stress = less BDNF
How do antidepressants work
- they work by affecting gene expression
- antidepressants increase GR expression
- they cause neurogenesis
- increase BDNF synthesis
Scanning techniques that can be used
- allows the study of networks
- functional connectvity
What is the function of the default mode network
- it is what comes on when rhere’s nothing to do
- daydreaming
- when the prefrontal cortex/porterior cingulate cortex/hippocamus is in action
Function of the default mode network
- ) Autobiographical details: projecting to other places in time and space
- ) Self reference
- ) Thinking about others
DMN in depression
- depressed people excessively ruminate
Tests with modern scanning on people in the acute psychedelic state
- reduced activity in the DMN
- reduced power in PCC
Introduction to entropy
- it is a measure of disorder/chaos
How does the brain try to reduce entropy
- Makes predictions
- called top-down processing
- initially: visual prediction until eventually core beleifs
what is depression a disease of
- ) Depression is a disease of reduced plasticity: reduced connectivity at the cellular level
- ) Depression is a disease of increased self-referential thinking: reduced connectivity at the interpersonal level
