Depression Flashcards
What is neurology?
→ Branch of medicine, diagnosis & treatment of nervous system disorders
What is psychiatry?
→ Branch of medicine, diagnosis & treatment of disorders that affect the mind and psyche
What is human behaviour a product of?
→ Product of brain activity
What is the brain a product of?
→ Genetics and environment
→ Experience
What is depressive disorder?
→ A low state marked by significant levels of sadness → lack of energy → low self worth → Guilt → related syndromes
What is a major depressive disorder?
→ A severe pattern of depression that is disabling and not caused by factors such as drugs or a medical condition
What are characteristics of affective disorders?
→ Disorders of mood rather than thought/cognition
What is unipolar depression?
→ mood swings in one direction
→ most common depressive illness
How many unipolar depression cases are caused by the environment?
→ 75%
How many cases of unipolar depression are caused by genetics?
→ 25%
What is bipolar depression?
→ Oscillation between depression and mania
What is mania?
→ Excessive exuberance → enthusiasm → self confidence →impulsive actions → aggression → irritability → delusions of grandiose
What are the criteria used for depression diagnosis?
→ DSM-IV or ICD-10
What are the criteria for depression?
→ Five or more of the symptoms during the same 2 week period
What are the emotional symptoms of depression?
→ Apathy → pessimism → negativity → low self esteem → feeling guilty → loss of motivation → indecisiveness
What are the biological symptoms of depression?
→ Reduced activity
→ Loss of libido
→ Sleep disturbance
→ Loss of appetite
What are the animal models of depression?
→ Learned helplessness
→ mother infant separation is reversed by antidepressants
What is the gender bias in depression?
→ It affects twice as many females as males
What is the lifetime prevalence of depression in men and women?
→ 10-25% in women
→ 5-12% in men
When does the first depressive episode happen?
→ late adolescence
→ early adulthood
What is depression comorbid with?
→ terminal and chronic illness → thyroid dysfunction → neurological disease → stroke → drug abuse
How many depressed individuals will attempt suicide?
→ 20%
If one twin has depression what is the probability that the other will get it too?
→ 40-50%
What are environmental factors that may lead to depression?
→ loss
→ Environmental stressors
→ Social isolation
What is the monoamine theory for depression?
→ that there is a deficit of monoamines
→ 5-HT
→ dopamine
→ NA
What is the evidence for the monoamine theory?
→ Overall reduced activity of dopaminergic and serotonergic systems
→ Reserpine depletes the brain of NA and 5-HT and induces depression
→ main antidepressant drugs increase amines in the brain
What is the evidence against the monoamine theory?
→ It is difficult to show deficits in the brain of NA and 5-HT
→ most antidepressants take several weeks to work but increase in amines is acute
→ some antidepressants are weak and have no effect on amine uptake
→ cocaine blocks amine uptake but has no antidepressant effect
→ increase in 5-HT is linked to aggression and not depression
What is the neuroendocrine theory?
→ there is hypersensitivity to the HPA axis
What neurons input to the hypothalamus?
→ noradrenergic
→ 5-HT
Describe how cortisol is produced?
→ Hypothalamus releases CRH (corticotropin releasing hormone)
→ CRH acts on the pituitary - release of adrenocorticotropic hormone (ACTH)
→ Cortisol release from the adrenal cortex in response to increased ACTH in the blood
What does CRH do?
→ mimics depression like symptoms
What is cortisol and CRH like in depressed patients?
→ Cortisol is higher
→ increased CRH in CSF
What suppresses and increases the HPA axis?
→ hippocampus suppresses HPA
→ Amygdala increases HPA
What are glucocorticoid receptor gene expression regulated by?
→ Early experience
What causes glucocorticoid receptor expression in the brain?
→ tactile stimulation after birth activates 5-HT pathways to the hippocampus
→ it triggers a long lasting increase in the expression of glucocorticoid receptors in the hippocampus
How do SSRIs affect glucocorticoid receptor expression i the hippocampus?
→ they increase it
Lack of what receptor is associated with depression and why ?
→ Decreased glucocorticoid receptors in the hippocampus (cortisol)
→ more cortisol is needed to bind and negatively feedback to the hippocampus
→ hippocampus downregulates the HPA axis
What is the neurogenesis theory for depression?
→ Evidence of neuronal loss and decrease in neuronal activity in the hippocampus and prefrontal cortex
What promotes neurogenesis?
→ ECT
→ antidepressants
What promotes neurogenesis during development?
→ 5-HT via BDNF (brain derived neurotrophic factor)
What increases BDNF?
→ SSRIs
What increases in the cortex of depressed people?
→ glutamate
Why does glutamate cause depression?
→ excessive glutamate leads to neurotoxicity which leads to neuronal death
Describe how excitotoxicity occurs
→ Chronic stress causes a big release of glutamate
→ Hyperactivation of NMDA receptors
→ Excitotoxicity occurs leading to neuronal loss
Describe how neurogenesis occurs mediated by NA and 5HT
→ Noradrenaline acts on alpha 2 receptors
→ 5-HT acts on 5-HT1A receptors
→ these cause beneficial gene transcription
→ increased neurogenesis and inhibition of neural apoptosis
What is an adverse effect of ECT?
→ Memory loss
What does psychotherapy help with?
→ overcoming negative views
What do tricyclic antidepressants do?
→ block reuptake of NA and 5-HT
What is an example of an SSRI?
→ Fluoxetine
What is an example of an NA selective reuptake inhibitor?
→ reboxetine
What do MAOI do?
→ block the degradation of 5-HT and NA
What does lithium do?
→ Stabilises mood
