Higgins Chapter 21 Review Flashcards
What are the three main arguments against the monoamine hypothesis as the only cause of depression?
- Medications take 6 to 10 weeks to reach full effectiveness
- Studies have failed to find consistent deficiencies in neurotransmitter levels
- Genome-wide association studies have not identified monoamine genes as culprits
What is the relationship between the frontal cortex and symptoms of depression?
Dysfunctional communication between the frontal cortex and subcortical regions
What imaging technique studies the synchronicity of different brain regions?
Functional connectivity
What is the default mode network?
A network that becomes active during rest or daydreaming
What is the effect of chronic stress on the hypothalamic–pituitary–adrenal (HPA) axis in depression?
Inability to turn down the HPA axis leading to excessive cortisol in the body which can overtime shrink the hippocampus.
What is the outcome of the dexamethasone suppression test in depressed patients?
They fail to suppress cortisol levels
What does increased cortisol from the adrenal gland cause in depression?
Hippocampal damage
What role does the nucleus accumbens (NAc) play in reward dysfunction related to depression?
Mediates the drive for rewards
Fill in the blank: Depression appears to result in the breakdown of the normal relationship between the _______ and the HPA axis.
hippocampus
What is neurogenesis?
The process by which undeveloped stem cells in the brain migrate and mature into neurons or glial cells.
What is the role of Brain-Derived Neurotrophic Factor (BDNF)?
Regulates the differentiation and survival of neurons.
What structural changes are observed in the brains of depressed patients?
Subtle volumetric loss, including smaller hippocampus, PFC, cingulate gyrus, and cerebellum.
What is one possible explanation for volume loss in depression?
HPA axis activation being neurotoxic to the brain.
What is a key factor linked to shrinkage of the brain in depression?
Failure of neurogenesis and growth factor proteins like BDNF.
What happens to BDNF levels in suicide subjects compared to controls?
Marked decrease in BDNF in the PFC and hippocampus.
Which interventions have been shown to increase BDNF in rats?
- Antidepressants
- Lithium
- Stimulation treatments (ECT, TMS, VNS)
- Estrogen
- Exercise
How do antidepressants affect BDNF levels in humans?
Increase serum BDNF levels significantly after treatment.
What is the relationship between BDNF and neurogenesis?
Increased BDNF leads to increased neurogenesis.
What effect does chronic stress have on BDNF mRNA in animal models?
Greatly reduces BDNF mRNA levels.
What does excessive methylation of histones do to DNA access?
Limits access to the DNA, affecting gene expression.
What is the proposed mechanism of depression according to recent studies?
Stress and genetic vulnerability decrease growth factor proteins due to DNA clogging.
What unexpected finding has been observed in postmortem studies of depressed patients?
Reduced number and density of glial cells in the PFC.
What is the rapid effect of ketamine in treating depression?
Can induce a robust antidepressant response within 2 hours.
What receptor does ketamine block?
N-methyl-d-aspartate (NMDA) receptor.
What is Deep Brain Stimulation (DBS) compared to?
A cardiac pacemaker for the brain.
What is a major challenge in using DBS for treating depression?
Lack of understanding of the pathology of depression.
What factors contribute to the development of depression according to the general consensus?
Interaction of dubious genes and difficult environmental events
What gene did Avshalom Caspi’s 2003 study focus on regarding depression?
Serotonin transporter gene
What are the two versions of the serotonin transporter gene?
Short allele and long allele
Individuals with which allele are predisposed to develop major depression when facing stressful events?
Short allele
What did a meta-analysis six years after Caspi’s study conclude about the serotonin transporter genotype?
No evidence of association with elevated risk of depression
What is a distinctive feature of bipolar disorder?
Episodes of mania
What has been a challenge in understanding the neuroscience of bipolar disorder?
Distinguishing differences from unipolar depression and healthy controls
What imaging technique has shown disrupted functional connectivity in manic patients?
fMRI
In manic patients, which two brain regions showed altered connectivity?
Amygdala and anterior cingulate cortex
What has been found regarding gray matter volume in bipolar patients after lithium treatment?
Significant increases in total gray matter volume
What do studies suggest about the relationship between the PFC and subcortical regions in bipolar disorder?
Abnormal interactions may be involved
