section 2

• Background


  • The biochemical explanation of mental illness
  • The genetic explanation of mental illness
  • Brain abnormality as an explanation of mental illness
• Biochemical explanation of mental illness: DEPRESSION

  The monoamine suggests that depression is due to low levels of a group of neurotransmitters called monoamines
• Monoamines include: dopamine, serotonin and noradrenaline
• Monoamines


  Important in regulating the limbic system in the brain, which controls emotion, drive and appetite
• Each monoamine has its own function, when they are depleted the effects link to depression
• It is thought that depression is caused by a reduction in all of the monoamines not just a single one
• You have 86 billion neurons in your brain!!
• Parts of a neuron

  • NEUROTRANSMITTERS
  • VESICLES
  • NEUROTRANSMITTERS
  • AXON
  • POST SYNAPTIC RECEPTORS
  • PRE-SYNAPTIC NEURON
  • SYNAPTIC GAP
• Serotonin


  A master neurotransmitter as it regulates the other monoamine transmitters
• Without the regulation of serotonin, erratic brain functioning and thinking patterns occur (as they other two neurotransmitters are not stable)
• What serotonin is responsible for

  • mood, well-being, stomach functioning and memory
• A lack of serotonin appears to be related to depressive symptoms such as low mood and a reduced appetite
• Noradrenaline


  This neurotransmitter is found in the hypothalamus and hippocampus
• What noradrenaline is responsible for

  • heart rate, concentration, attention, alertness and energy
• A lack of noradrenaline appears to be related to depressive symptoms such as disruption in sleep patterns and lack of energy
• Dopamine


  This neurotransmitter is responsible for: motivation, pleasure and reward
• A lack of dopamine appears to be related to depressive symptoms such as attention, less interested in pleasure and reward
• Genetic explanation of mental illness: DEPRESSION


  If there is a high prevalence of e.g. depression in a family, would you conclude that this must be the genetic explanation?
• How would you investigate if there are genes that run in families for mental health conditions?
• Methods to investigate genetic links

  • Gene mapping
  • Family studies
  • Twin studies
  • Adoption studies
• Family studies


  Children who have a parent with bipolar depression have an increased chance of developing it
• A child with one parent with bipolar has a 4.4% risk of being diagnosed with the same disorder, compared with a 0.63% risk of the general population
• Twin studies


  • Concordance rates for major depression in MZ twins are between 30-50%
  • Concordance rates for major depression in DZ twins are between 12-40%
• Results of twin studies consistently and strongly suggest that major depression has a significantly causative genetic component
• Adoption studies


  • Few adoption studies have been conducted
  • The ones that have, offer weak support for the genetic explanation
  • Only one study by Wender et al (2004) did show clear genetic support. They found that the biological relatives of a depressed adoptee were 8x more likely than adoptive relatives to also have depression
• Evaluation of genetics


  • Ogilvie et al (1996) compared the hSERT gene in 39 people with major depression and 193 people from the general population
  • They found a significantly higher occurrence of short alleles in the depression group
  • Goldman et al (2010) found that those with a shortened allele reacted more negatively to stressful events than those with a "normal" hSERT gene
• These results suggests that the hSERT gene could be responsible for inheriting depression
• Brain facts


  • How many lb does an adult brain weigh? about 3 pounds.
  • What percentage of the human brain is made up of water? About 75 percent
  • The human brain will grow how many times in the first year of life? three times
  • How many neurons are in the human brain? One hundred billion
  • Is it a fact of fiction that we only use 10% of our brains? Myth
  • The fastest speed for information to pass between neurons is how many mph? 250 mph
  • Phantom limb pain syndrome is when the central nervous system, which includes your brain, continues to feel the pain of a limb that has been amputated. True
  • The brain can't feel pain. It interprets pain signals sent to it, but it does not feel pain. True
  • Is brain freeze an actual thing? Yes
  • During the mummification process, Egyptians would usually remove the brains through which part of the body? the nose
  • Eyewitness accounts of criminal suspects is usually only about 50 percent accurate
  • Traumatic events can also affect the brains ability to remember details
  • Your brain uses 20 percent of the oxygen and blood in your body
  • It develops back to front, your frontal lobe is still under construction and will be until you are approx 25-30yrs!
• Using the wealth of biological knowledge you have gained so far, what areas of the brain can you identify and what are the functions?
• The location for awareness of what we are doing within our environment (our consciousness)
• Brain abnormality explanation of mental illness: DEPRESSION


  • The brain of the person with bipolar depression appears to differ from the "neurotypical" person
  • The limbic system shows differences in terms of the amount of grey matter and the levels of activity in areas of the brain
• Limbic system


  Includes the amygdala and the hippocampus
• Amygdala


  • Changes in levels of activity in the amygdala are associated with the symptoms of depression
  • Increases in activity have been found when depressed patients are given negative stimuli such as a sad face
  • The opposite is true when given positive stimuli (happy face=decreased activity)
  • The amygdala regulates emotions, which is disrupted in people with depression
• Hippocampus


  • The hippocampus is smaller in size in patients with depression (it can be reduced in volume by upto 20%)
  • The more severe the depression, the more severe the loss of grey matter in the hippocampus
  • The reduction in grey matter, and therefore function in the hippocampus may explain why people with depression process emotionally charged memories in dysfunctional ways
• ECT


  • Historically used to treat schizophrenia, now used to treat depression
  • Involves passing an electrical current through the brain to induce a seizure
  • Given with anaesthetic and muscle relaxant to prevent injury
• How ECT is administered

  1. Patient is given a general anaesthetic and muscle relaxant

  2. Electrodes are placed on the patient's head

  3. Approx 0.6 amps of electrical current is passed through the brain for half a second, causing a seizure

  4. Usually 6-8 treatments are given over 3-4 weeks
• How ECT works


  • Doctors are not sure exactly how it works
  • May change neurotransmitter activity, stimulate blood flow in brain areas linked to depression, or stimulate growth of new brain cells and pathways
• Types of ECT


  • Unilateral ECT - electrodes on one temple
  • Bilateral ECT - electrodes on both temples, more effective but more side effects
  • Unilateral ECT is used less in the UK
• Antidepressant drugs


  • SSRIs - selectively inhibit reuptake of serotonin, increasing its levels in the synapse
  • Tricyclics - also affect serotonin but have more severe side effects
  • SNRIs - increase both serotonin and noradrenaline
• It takes 3-4 months of daily SSRI use to have much impact on depression symptoms