Biological Explanations of Uni-Polar Depression
- Created by: bethcx
- Created on: 25-02-16 09:40
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- Biological Explanation of Uni-Polar Depression
- Brain Structure
- Development in neuroscience and improved scanning techniques have found that dysfunction and abnormalities in the brain are associated with depression.
- Frontal Cortex
- It's important in maintaining beliefs about goals and the means to achieve them.
- Drevets
- Found that depression is associated with lower than normal activation in this area.
- This means that they're less likely to believe they can achieve goals.
- Found that depression is associated with lower than normal activation in this area.
- MRI scans have shown a reduction in the size of frontal lobes in depressed people.
- Drevets
- It's important in maintaining beliefs about goals and the means to achieve them.
- Limbic system
- Consists of a number of structures yhat are involved in motivation, mood, and emotions.
- Amyglada
- Part of the limbic system
- It's to do with the reaction to threat and increased activation of this is seen in depressed individuals and is thought to affect their ability to process and judge 'threatening' information.
- This over activation interprets information negatively and believes it to be worse than it actually is.
- Frontal Cortex
- Development in neuroscience and improved scanning techniques have found that dysfunction and abnormalities in the brain are associated with depression.
- Genetics
- Family Studies
- Winkour
- Found depression in just over 10% of first degree relatives, compared to only 4.9% of control relatives.
- Earlier research found that up to 50% of the children of depressed individuals showed symptoms of depression,
- However, living with someone with depression may lead to their child feeling isolated to due being shown little affection, meaning it could be down to environmental factors.
- Earlier research found that up to 50% of the children of depressed individuals showed symptoms of depression,
- Found depression in just over 10% of first degree relatives, compared to only 4.9% of control relatives.
- Winkour
- Twin Studies
- McGuffin
- Looked at over 200 pairs of twins. If a MZ twin had unipolar depression, there was a 46% chance the other one would. For DZ twins the concordance rate was 20%.
- The concordance rate isn't 100% which suggests environmental factors
- It's difficult to separate environment factors, expecially for twins who have been exposed to the same life experiences,
- Looked at over 200 pairs of twins. If a MZ twin had unipolar depression, there was a 46% chance the other one would. For DZ twins the concordance rate was 20%.
- McGuffin
- Adoption Studies
- These eliminate environmental factors.
- Wender
- Investigated the families of adopted individuals in Denmark who had severe unipolar depression. The biological parents of depressed adoptees had a higher incidence of severe depression than the biological parents of non-depressed adoptees.
- This means that only severe depression may be caused by genetic factors.
- It's only on Danish individuals meaning it's not representative
- Investigated the families of adopted individuals in Denmark who had severe unipolar depression. The biological parents of depressed adoptees had a higher incidence of severe depression than the biological parents of non-depressed adoptees.
- Wender
- These eliminate environmental factors.
- Family Studies
- Neurotransmitters
- It's argued that low levels of the neurotransmitters serotonin (5-HT) and noradrenaline (na) reduce firing of neurons at the synapse causing symptoms.
- McNeal
- Found that cerebrospinal fluid in depressed patients contained less of a major 5-Ht by product, showing they have lower levels of this in their brains.
- Similarly, byproducts of na are low in the urine of depressed patients.
- Found that cerebrospinal fluid in depressed patients contained less of a major 5-Ht by product, showing they have lower levels of this in their brains.
- The basic theory of there being low levels of 5-HT and na has been critisced as antidepressants raise levels of 5-HT and na within days but patients don't feel better for weeks- suggesting the cause is more complex.
- McNeal
- Tryptophan is a precursor (building block) of 5-HT and is required for it's production,
- Delgado
- Found that a reduced tryptophan diet caused relapse in 67% of a group previously diagnosed with depression. They recovered when the diet stopped.
- Delgado
- It's argued that low levels of the neurotransmitters serotonin (5-HT) and noradrenaline (na) reduce firing of neurons at the synapse causing symptoms.
- Brain Structure
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