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Psychology 4 10


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Psychology 4 10

  1. 1. Quick Write<br />
  2. 2. Psychology 4.10 <br />Biological View of Depression<br />
  3. 3. When you leave, you will be able to discuss the biological view of depression including genetic factors.<br />The goals of today<br />
  4. 4. According to the Biological perspective/model, what would the source of depression be?<br />
  5. 5. Three types of studies seem to suggest that people inherit a predisposition to depression:<br />Family Pedigree studies<br />Twin Studies<br />Adoption studies<br />The Biological View of Depression (Genetic Factors)<br />
  6. 6. Select people suffering from depression as probands (the person who is the focus of the study).<br />Then, they examine their relatives and see whether depression is present in their family.<br />To have some sort of conclusive support for a genetic link, the proband’s relatives should have a higher rate of depression than the average population. <br />Some researchers report as much as 20% of relatives (in family pedigree research) compared to 10% of the general population.<br />Family Pedigree Studies<br />
  7. 7. Examined sets of twins and rates of depression. <br />200 pairs of twins were looked at.<br />When a MZ twin suffered from depression, there was a 46% chance that the other would also have a similar diagnosis.<br />When a DZ twin had depression, the other twin had a 20% chance of developing the disorder.<br />Twin Studies: Gershon and Nurnberger (1995)<br />
  8. 8. One specific study looked at the families of adopted persons who had been hospitalized for depression in Denmark. <br />The biological parents of these adoptees had a much higher incidence of severe depression than the biological parents of the control group.<br />Adoption Studies<br />
  9. 9. Briefly, explain the importance of twin studies and how they are used to study depression from the biological perspective.<br />Quick Write<br />
  10. 10. Neurotransmitters carry messages from one neuron to another. <br />Biochemical Factors<br />
  11. 11. Responsible for various physical and cognitive activities: Sleep, pleasure, arousal, memory, muscle contraction, etc.<br />Neurotransmitters<br />
  12. 12. Low activity of two neurotransmitters: norepinephrine and serotonin, have been strongly linked to depression.<br />This relationship is supported by two important pieces of evidence (discovered in the 1950’s):<br />1. Medical researchers discovered that reserpine and other medications for high blood pressure can cause depression. Why do you think that might be?<br />2. The conclusion that was drawn was that depression could be relieved by increasing the activity of norepinephrine or serotonin. <br />Neurotransmitters and Depression<br />
  13. 13. These findings led some theorists to conclude that depression is a product of low norepinenphrine activity.<br />Neurotransmitters and Depression<br />
  14. 14. Norepinephrine belongs to a class of chemicals called catecholamines.<br />This theory aims to connect the onset of depression to lowered levels of catecholamines.<br />Catecholamine Theory<br />
  15. 15. Produced evidence that drugs which decrease the levels of noradrenaline can produce depression-like symptoms. <br />In one study, participants were given a drug called physostigmine. <br />Within minutes of receiving the drug, some felt intense feelings of self-loathing and suicidal thoughts.<br />Janowsky et al. (1972)<br />
  16. 16. Likewise, some researchers identify a connection with serotonin.<br />Serotonin is belongs to the indoleamines, thus the indoleamine theory relates to lower levels of serotonin.<br />Indoleamine Theory<br />
  17. 17. For years, it was believed that low activity of either of these neurotransmitters was capable of producing depression. <br />Researchers now believe that it is the interaction between the serotonin and norepinephrine systems. <br />Some research suggests that, in those suffering from depression, there is an overall imbalance of neurochemicals.<br />Another variation of this theory states that serotonin helps regulate other neurotransmitters. Low levels of serotonin activity disrupts the activity of the other neurotransmitters.<br />The Interaction of these biochemicals<br />
  18. 18. The endocrine system may also play an important role the onset of depression.<br />What does the endocrine system produce?<br />The role of the endocrine system<br />
  19. 19. People suffering from depression have been found to have abnormal levels of cortisol(hormone released during times of stress).<br />This seems consistent with the prevalence of depression in certain segments of society. <br />Why?<br />Cortisol levels and depression<br />
  20. 20. Another hormone tied to depression is melatonin. <br />This hormone plays an important role in our circadian rhythms.<br />This hormone is released by the brain’s pineal gland only when dark. <br />In animals, it helps control hibernation, activity levels, and the reproductive cycle. <br />As nights grow longer, they release more and more melatonin. During the spring, melatonin secretions are on the decline.<br />Melatonin<br />
  21. 21. For humans, heightened melatonin levels in winter seem to slow us down. <br />Some humans may be so sensitive to these heightened secretions, they find it impossible to carry on about their daily business.<br />Their slowdown takes the form of depression each winter. This pattern can result in seasonal affective disorder (SAD)<br />Melatonin and depression<br />
  22. 22. Not surprisingly, SAD is less common in areas that receive more annual sunlight.<br />Some who are susceptible to melatonin decreases may be sensitive in the other direction as well: Manic episodes during the summer months may take place. <br />SAD<br />
  23. 23. Some of most cited research as relied on analogue studies (depression-like symptoms are created in animals).<br />Until recent years, technology was limited. Biological studies of human depression had no way to measure brain activity directly: Neurotransmitters were estimated by measuring the activity of chemical by-products in the bloodstream, urine, and spinal fluid. <br />Measures of these substances may not directly reflect neurotransmitters.<br />Current technology has improved these limitations, but the progress is slow. <br />Limitations of the Biological explanation of depression<br />