MDD

Question 1

definition of MDD

Answer 1

A psychophysical state characterized by emotional pain, troublesome social interactions, reduction in pleasure

Question 2

symptoms

Answer 2

• Isolation
• Lack of energy/appetite/concentration/sleep
• Thoughts of death
• sadness

Question 3

incidence

Answer 3

280 million people have MDD

Question 4

limits of selection

Answer 4

• Natural selection isn’t strong enough to eliminate depression genes
• It appears post puberty so cant select against
• Indirect genetic inheritance where genes code for multiple traits (good genes outweigh bad ones so don’t select out)

Question 5

evolutionary hypothesis

Answer 5

• Social navigation hypothesis: Depression has evolved to enhance fitness in ancestral environment through functional social rumination and motivation to navigate and survive in unideal social environments
• Social rumination function: cognitive changes occur that force a person to focus on complex social problems in order to find a solution
• Social motivation function: negative effects can force an unwilling social partner to make changes and provide help

Question 5

genetic predisposition

Answer 5

• 40-50% heritable and about 50/50 genes/environment
• No singular gene but a combo of genes predispose individuals
• Serotonin transporter: 5HTT/SLC6A4
• Tryptophan hydroxylase: TPH2 on chromosome 12q which when mutated results in 80% loss in serotonin production (only in suicidal patients)

Question 6

previous and current treatments

Answer 6

• Previous: exorcism, “medication”, bloodletting, diet/herbs/music/marriage,
• Current: electroconvulsive therapy, SSRIs

Question 7

Evolution: clinical implications

Answer 7

• Limit medication use
• Use talk therapy to validate self
• Find underlying causes
• Look at content of ruminations for clues

Question 8

Limitations

Answer 8

• Severe depression = maladaptive
• Twin studies only show 30% heritability
• Talking vs medication