Thank you everyone for the great discussion today. As promised, I would like to follow up with some of the topics discussed in class today as well as in the lecture so you have a physical write up to reflect on.
Parkinson's
Hopefully the videos in class shed some light on what the movement disorders actually look like as well as the medication induced dyskinesias. Again, the supplemental slide at the end of the lecture also provides some good videos on how these movements may manifest in patients. For slide 8, as stated articulate, the side effects for the medications highlighted really extends to all medications in their class. For the first category, Levadopa/Carbidopa is really the only medication in the class of L-dopa/decarboxylase inhibitors. For the second category, of MAOI's, these side effects are similar to those experienced with COMT inhibitors as well. The third category of dopamine agonists includes medications like pramipexole which have a unique side effect of compulsive disorders such as reward seeking behavior (drug/sex/gambling addiction) in individuals who previously had no history of that behavior, with the behavior ceasing after stopping the medication. Finally, the last category are the anticholinergics which are not as commonly seen, primarily because their side effects are unpleasant especially given their mild efficacy. Their use is typically limited to only very early detected and mild forms of the disease.
Schizophrenia
Schizophrenia is not well understood but involves neuronal pruning that occurs as adolescents reach maturity. Essentially it is known that there is overpruning of neurons in certain areas of the brain that leads to schizophrenia. That is, there are physical changes in the organization of the brain in schizophrenics. Over activity of dopamine in certain brain areas leads to positive symptoms and under activity in other areas leads to negative symptoms. The medications aim to correct dopamine output in the brain and the 1st versus 2nd generation really reflect our early understanding of dopamine and schizophrenia: 1st generation block dopamine everywhere which helps with the positive symptoms that are most characteristic of schizophrenia, but do very little for the negative symptoms and can actually make them worse. Now that we understand that the disease isnt strictly dopamine deficiency, we treat with the 2nd generation antipsychotics which aim to correct dopamine levels in the brain pathways involved and discussed in the articulate. Looking at slide 10 with the brain pathways, it makes sense that if you are exclusively blocking dopamine (and from what you know about parkinson's disease) that you would expect to see movement disorders (extrapyramidal symptoms) appearing as a result of the medications action on the nigrostriatal pathway. Also, to put into words what was mentioned in the articulate, dopamine normally suppresses prolactin release in the tuberoinfundibular pathway, therefore, blocking its action (like with 1st generation antipsychotics) can have the effect of removing that inhibitory action of dopamine on prolactin release. This leads to prolactin release in some patients and thus lactation.
Alzheimers
There are many hypothesis surrounding alzheimers. What we know is that there is a loss of cholinergic activity in the brain which contributes to the cognitive decline. The brain physically atrophies as illustrated in slide 14. Acetylcholineesterase medications prevent the breakdown of ACh so that ACh released has more of an effect, but looking at the side effect profile, these medications are not perfect by any means. The NMDA antagonists block NMDA receptors at excitatory glutaminergic neurons, which are associated with cell death. In this way, NMDA antagonists slow progression of Alzheimer's. By contrast, as we discussed, medications for Parkinson's do not slow progression, only treat symptoms.
Depression
There are many many different antidepressants. Most fall into the classes discussed but there are actually more medication classes that were not discussed simply because they are less related to PT. In general, a lot of SSRI's also carry some weight gain as an adverse effect which may be of concern to PT, but none as much as mirtazepine, which is preferred in the elderly for that reason as many elderly patients are underweight. The sedation also often helps with agitation in the elderly making it more ideal for many elderly patients experiencing depression. Serotonin syndrome, as discussed in class, occurs when 2 or more serotonergic medications are combined. Different serotonergic medications carry different risk levels for serotonin syndrome, but the take home is if someone is taking two or more medications that you know increases serotonin to some degree, its worth investigating what the risk is. This may be as simple as calling a pharmacist, ideally the patients pharmacist to alert them, but could be a life-saving intervention.
Benzodiazepines
Just a quick note on benzos, they are on BEERS Criteria as medications that should not be used in elderly populations due to fall risk. They also carry significant abuse potential and when combined with alcohol, can be fatal. As emphasized in the articulate and in lecture, we prefer for patients in the outpatient setting to not be on benzodiazepines, but its still common to see this, at least PRN. It would be a little more alarming if a patient was on a scheduled benzodiazepine and this is a situation where the provider may have a reason, but might be worth having a discussion with the provider about. As you know, benzodiazepines are very sedating and a patient on a benzo that is scheduled are likely to be constantly sedated, weak, and dizzy - not optimal for PT sessions or for quality of life.
Finally, thank you again for your participating today. I was thrilled by the level of understanding of these medications after only a brief articulate and your ability to make the connections between things mentioned on the articulate and the case today. Excellent job everyone :D
If you have followup questions to todays section on this topic, please post them as a reply to this thread and I will try to respond as timely as possible.