Common Medical Myths & Misconceptions. Misconceptions vs. Myths For the purpose of this Discussion: Misconception = Common mistake, but generally not

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Common Medical Myths & Misconceptions Slide 2 Misconceptions vs. Myths For the purpose of this Discussion: Misconception = Common mistake, but generally not perpetuated by schools and licensure exams. This presentation will cover 5 common medical misconceptions. Myth = More than just a common mistake; currently standard practice and propagated by schools and licensure exams. This presentation will cover 3 medical myths. Slide 3 Misconception #1: Cyclothymia Cyclothymia is: a)An endocrine disorder that results in an underproduction of thyroxine b)An immunological disorder related to a mutation in the MHC gene c)A mood disorder related to dysfunction of the thymus in the brain d)None of the above e)Dont Know Slide 4 Cyclothymia Cyclothymia is: a)An endocrine disorder that results in an underproduction of thyroxine b)An immunological disorder related to a mutation in the MHC gene c)A mood disorder related to dysfunction of the thymus in the brain d)None of the above e)Dont Know Slide 5 Cyclothymia a)An endocrine disorder that results in an underproduction of thyroxine b)An immunological disorder related to a mutation in the MHC gene c)A mood disorder related to dysfunction of the thymus in the brain d)None of the above (11.1%) e)Dont Know Cyclothymia has nothing to do with the thymus Slide 6 What is the Thymus? Cyclothymia and dysthymia are named after the greek word thumos or thymos, meaning spiritedness or emotion (Thumos, 2014). The thymus is also named after thymos though it has nothing to do with emotions, but the Greeks didnt know that when they named it, resulting in etymological confusion that has lasted to this day. To add further confusion, the thymus is right next to the thyroid on the trachea, and nobody ever talks about the thymus because its not a vital organ in children and adults, so most people dont know what it does and the two are frequently confused. Slide 7 What Does The Thymus Do? During embryonic development lymphocytes go to the thymus to mature. Lymphocytes that fail to interact with MHCs are killed, because they wouldnt be able to do their job if they cant interact with MHCs on other cells. Lymphocytes that have strong affinity for self proteins are also killed here because they would cause autoimmunity. Failure of the thymus to kill cells that have affinity for self proteins is thought to be a possible cause of many autoimmune disorders including Diabetes Mellitus Type I (Geenen et al., 2005). The thymus prunes your lymphocyte population so only potentially useful lymphocytes ever make it into circulation. By your early teens your thymus starts to atrophy and turn into fat tissue and can be removed without any immune system compromise because its work has already been done (Thymus, 2015). Slide 8 Misconception #2: Blood Is blood always red? a)Yes b)No c)Dont Know Slide 9 Blood Is blood always red? a)Yes b)No c)Dont Know Slide 10 Blood Is blood always red? a)Yes (66.7%) b)No c)Dont Know Slide 11 Blood is Always Red. This is a metaphor Blood is bright red when oxygenated, and dark red when deoxygenated. Slide 12 Blood is Always Red So why are veins blue then? This is a metaphor And why does cyanosis happen? Slide 13 Blood is Always Red This isnt a popular fact to share at the water cooler, because its a little bit complicated. 1)The fats and proteins in skin dont absorb much light; they reflect it back out. Red light travels deeper than blue light before getting reflected back out (its better at getting through those proteins and fats). 2)Blood, unlike skin, absorbs light of all wavelengths, but it absorbs blue light more than red, so it appears red. 3)Deoxygenated blood in veins, like oxygenated blood in capillaries, reflects red light more than blue light, but compared with oxygenated blood it reflects more blue light (but still less blue than red, so it still looks red). Kienle et al., 1996 Slide 14 Even though veins absorb more blue light than red light if exposed to equal amounts of both, they dont get exposed to equal amounts of both; they absorb a disproportionately large amount of red light under your skin because much of the blue light gets reflected back out by the proteins and fats in your skin before it can reach the vein. Blood is Always Red Slide 15 Even so, the light that comes out over top of a vein still winds up being more red than blue, but the effects discussed in the previous slide make it proportionately more blue than the surrounding skin, in a ratio of about 3 parts red to 2 parts blue (40% blue [if we ignore all the colors except red and blue for the purpose of comparison]), while the surrounding skin is 5 parts red to 3 parts blue (37.5% blue) (Kienle et al., 1996). So the light from skin is mostly red, and the light from veins is mostly red, but theres more blue in the light being reflected above veins because the veins removed more of the red light than gets removed in the surrounding skin because the red light is better at getting all the way down to the veins, and deoxygenated blood reflects more blue than oxygenated blood in surrounding capillaries. Slide 16 Blood is Always Red Color perception is skewed by our brains. The light coming out above veins is more of a reddish maroon than a blue, but it looks blue because its surrounded by a redder area. If you put something purple next to something red, it sometimes looks blue. This phenomenon is called relative perception. Other examples of relative perception illusions: Different people perceive different colors in this dress. The red squares in the top diamonds are actually the same color. The green squares in the bottom two diamonds are also the same color. Slide 17 But back to the blood color responses for a second. Is blood always red? a)Yes (66.7%) b)No c)Dont Know But this is probably not reflective of the actual proportion of people that think that deoxygenated blood is blue, due to a type of testing bias caused by the quiz itself: the Hawthorne effect Most people got it right Slide 18 The Hawthorne Effect It is likely that people that see the question: Is blood always red? on a suspicious quiz will draw the conclusion that the question is only being asked because the answer is counter- intuitive, which makes the process of elimination very easy for a yes or no question, artificially inflating the proportion of correct responses. So the blue blood misconception is likely more prevalent than these results suggest. Slide 19 Misconception #3: Bipolar Disorder Which of the following scenarios fit the diagnostic criteria for either type I or type II bipolar disorder? a)No history of manic or depressive episodes. Currently experiencing a major depressive episode b)No history of manic or depressive episodes. Currently experiencing a manic episode c)Has experienced more than 2 years of alternating hypomanic and minor depressive episodes d)None of the above e)Dont know Slide 20 Bipolar Disorder Which of the following scenarios fit the diagnostic criteria for either type I or type II bipolar disorder? a)No history of manic or depressive episodes. Currently experiencing a major depressive episode b)No history of manic or depressive episodes. Currently experiencing a manic episode c)Has experienced more than 2 years of alternating hypomanic and minor depressive episodes d)None of the above e)Dont know Slide 21 Bipolar Disorder Which of the following scenarios fit the diagnostic criteria for either type I or type II bipolar disorder? a)No history of manic or depressive episodes. Currently experiencing a major depressive episode b)No history of manic or depressive episodes. Currently experiencing a manic episode (0%) c)Has experienced more than 2 years of alternating hypomanic and minor depressive episodes d)None of the above e)Dont know All you need for a type I bipolar disorder diagnosis is mania. You almost always see depression as well, but it is not necessary for diagnosis, and it is not part of the DSM5 diagnostic criteria. Slide 22 Bipolar Disorder While Bipolar II does require at least one episode of MDD, Bipolar I does not. It doesnt even require mild depression. It is possible for an individual to be diagnosed with Bipolar I disorder based solely on having had one or more full manic episodes (Bipolar I Disorder, 2015). These asymmetrical criteria are a product of the fact that there is a name for having depression with no elevated mood distinct from "bipolar disorder" (namely depression or MDD), but there is no special name for having elevated mood or mania with no depression distinct from bipolar disorder. This leads to a little bit of confusing asymmetry in the diagnostic criteria of bipolar I and bipolar II disorders. The wording in the textbook is misleading as well. On page 429 our text says "A bipolar disorder is characterized by mood swings from profound depression to extreme euphoria," which makes it sound like depression is a necessary symptom for any bipolar disorder diagnosis, though it is not (Lewis et al., 2011). Slide 23 Mood Disorder Chart Depressed sometimes but never manic? Depression Slide 24 Mood Disorder Chart Hypo-manic sometimes & majorly depressed other times? Type II Bipolar Depressed sometimes but never manic? Depression Slide 25 Mood Disorder Chart Hypo-manic sometimes & majorly depressed other times? Type II Bipolar Hypomanic sometimes & minorly depressed other times? Cyclothymia Depressed sometimes but never manic? Depression Slide 26 Mood Disorder Chart Manic sometimes & depressed other times? Hypo-manic sometimes & majorly depressed other times? Type II BipolarType I Bipolar Hypomanic sometimes & minorly depressed other times? Cyclothymia Depressed sometimes but never manic? Depression Slide 27 Mood Disorder Chart Manic sometimes but never depressed? Manic sometimes & depressed other times? ? Hypo-manic sometimes & majorly depressed other times? Type II BipolarType I Bipolar Hypomanic s