depresia Flashcards
what is depression
persistent feeling of severe despondency and dejection
What are the 3 main elements according to the DSM 5
A. 5 or more symptoms present for at least a 2 week period
Symptoms result in a significant change from previous functioning
Include at least 1 of: depressed mood or loss of interest of pleasure
b. cause clinical significant distress or impairment in social, occupational or other functioning
c. should mot be direct physiological effect of a substance or a general medical condition
what are the major symptoms of depression
depressed mood most of the time - something that is obvious both to the person and others who are close to the patient
diminished interest or pleasure in vast majority of activities the person was engaged with
loss or gain in weight
changes in quality and quantity of sleep
motor changes - agitation
fatigue
feelings of wrothlessness or inappropriate guild
diminshed ability to concentrate
reccurent thorughts of death
what is the prevalence of depression
lifetime - chance of having depression at some point in life: 6-25%
high income countries have higher rate of depressed patients
annual prevalence - about 4%
more present in females
why might high income countries have higher prevalance
poor countries may lack infrastructure to collect data on depression, and are less likely to recognise it as an illness
what are the causes of depression
biological
- NT
- brain, vascular damage
genetic
-family studies
-twin studies
environmental
What is the role of NT in depression
depression related to abnormality in three main NT:
serotonin, noradrenaline and dopamine
What is the role of serotonin, noradrenaline and dopamine usually?
serotonin - calming and inhibiting action
noradrenaline - affects motivation, ability to focus, energy
dopamine - pleasure, satisfaction and reward
How is serotonin implicated in depression?
decrease in serotonin is linked to depression
Imaging studies show abnormalities in serotonin receptor density and in transporters in people with depression
What is evidence of serotonin involvement
Drugs which block serotonin re-uptake can ameliorate depression
what is the limitations of serotonin involvement
recent review suggests no consistent evidence of association between serotonin and depression
no support for the hypothesis that depression is caused by lowered serotonin activity or concentrations
How is noradrenaline implicated in depression?
regulating emotions
engaged in arousal
activities that reflect ability to concentrate
depressed mood is associated with a deficiency of noradrenaline in areas such as the brain stem and the locus coeruleus which projects to the limbic system, involved in regulating emotions
low levels of noradrenaline - emotional withdrawal, concentration and memory deficits
what is evidence of noradrenaline involvement
Drugs which block noradrenaline re-uptake can ameliorate depression
How is dopamine implicated in depression?
low dopamine levels may explain low sense of pleasure and reward in depression
inability to experience pleasure - one of the symptoms required for diagnosis
imaging studies show abnormalities in dopamine receptor density and in transporters in depressed patients
What are the key findings in studies of NT
in depression NT are involved in:
-circuits that regulate emotional arousal
-regulate a reward network (ventral striatum with orbitofrontal and media prefrontal regions)
what are limitations of findings
data makes it unclear whether NT abnormalities reflect a deficit, a consequence, a risk factor, or a compensatory mechanism in depression
the involvement of NT does not mean they cause depression
what may cause these limitations
depression is a heterogeneous disorder
NT are part of a complex system that interacts with brain structure and function, genetics and the environment
what brain regions are implicated in depression
hippocampus
anterior cingulate cortex
prefrontal cortex
what is hippocampus like in depression
hippocapmmus is smaller in patients with depression than controls
smaller by 20%
chemical - cortisol which is released to alert the body to react to stimuli that are considered to be dangerous
when cortisol is chronically released, it would damage certain areas of the brain, one being hippocampus
that results in reduction in the ability to encode new information - hippocampus is key area for memory and encoding
what happens to hippocampus if you leave depression untreated
leaving depression untreated for certain amount of time leads in consistent reduction in the volume of hippocampus
what is the role of anterior cingulate cortex in depression
engaged in tasks that require resolving a conflict
engaged in memorising information
healthy controls were able to remember a short paragraph - activation in anterior cingulate and hippocampus
patients with depression were not performing well in memory task - lack of activation in these regions
what is the role of prefrontal cortex in depression
patients and healthy controls viewed emotional and neutral film clips
patients with depression were less good at a task that required processing emotional stimuli
activated prefrontal cortex more than healthy controls
indicated dysfunctional use of these areas
what are the problems with brain imaging in depression
despite the fact that this info is useful, it has little impact on clinical practice
because are findings contributing to the cause of depression or result of having depression
how to address these issues
look at ppt longitudinally
try to test ppts before the onset of illness - recruit at risk ppts - those who might have a family history of depression and are more likely to develop depression
what have brain images shown about studying people at risk of depression
3 groups:
-at risk ppts
-healthy controls
-patients with depression
Results:
1. at risk group had smaller right hippocampal and dorsolateral PFC volumes than controls
- at risk groups had smaller right hippocampal than patients with depression - those ppts with depression were under treatment and the treatment helped to ameliorate the symptoms and some of the brain features
what have family studies shown about genetic influence in depression
children of depressed parents have 50% chance of developing a disorder of some kind
20-40% chance of developing depression
what have twin studies showed
higher concordance rates among monozygotic than dizygotic twins - supports genetic influence
heritability of depression is thought to be 31-42%
how do we measure genetic effects through molecular genetics
study of chromosomes and gene expressions
genetic and environmental effects
study of genes involved in regulating serotonin
1,037 children assessed at ages 3,5,7,9,11,13,15,18,21,26
looked at whether genes were predicting the possibility of developing depression when this was combined to being exposed to stressful events
whether ppts had 2 short alleles which are associated with decreased serotonergic function - and therefore highest risk of developing depression
1 short and 1 long allele - some risk
2 long allele - little risk
measure the number of stressful life events
RESULTS:
group that has 2 short allele + stressful life events = increased risk of self-report depression symptoms
when there is a genetic profile combined with stress this results in higher probability of developing depression
when there are no stressful life events, the 3 groups are equal in terms of self reported depression symptoms
so allele alone do not correspond to depression. only when they are combined with stressful situations
What is depression like in late life
depression common in ageing
this is typically associated with health problems
less than 1/4 of older adults with depression receive treatment
low mood is common and often undiagnosed
in late life depression, treatment is not often successful
even if mood is stabilised there are still residual cognitive deficits
what is vascular depression
vascular damage that accumulates with age
vascular damage reduces integrity of white matter - some parts of the brain are less effective at communicating with each other
it disrupts the circuits that underlie emotional regulation - likely to result in late life depression
