FL4 PSY/SOC Q31

la kraken
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Joined: Tue Jul 18, 2017 4:16 pm

FL4 PSY/SOC Q31

Postby la kraken » Tue Jul 18, 2017 4:21 pm

For question 31, "A much-feared outcome of Alzheimer's disease is:" The answer is "senile dementia." I am having trouble understanding this answer because I thought that Alzheimer's is a branch of dementia. So, if Alzheimer's falls under the dementia umbrella, how can senile dementia be an OUTCOME?

Does this mean that Alzheimer's can progress into another form of dementia, called senile dementia?

Thanks for any responses!
NS_Tutor_Andrew
Site Admin
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Joined: Mon May 23, 2016 1:47 pm

Re: FL4 PSY/SOC Q31

Postby NS_Tutor_Andrew » Tue Jul 18, 2017 5:21 pm

Hi la kraken,

Excellent question! There are two levels to look at this: first, getting the question right; and second, the bigger picture. In terms of getting the question right, sometimes for the MCAT you're put in the position of needing to choose the least bad answer. Even given your (entirely reasonable) question about the word "outcome," "senile dementia" is still far more topically relevant than the other answer choices, so it's the best choice.

In terms of the bigger picture, it's not quite right to treat "dementia" and "Alzheimer's" as synonyms -- dementia essentially refers to a pattern of mental deterioration as manifested behaviorally, and can be due to a variety of causes (although Alzheimer's is a common one). Alzheimer's is a disease process involving the buildup of beta-amyloid plaques and neurofibrillary tangles in the brain. Theoretically, you need to look at a sample of someone's brain tissue to definitively establish Alzheimer's, although this isn't often done in practice for obvious reasons. The idea, then, is that Alzheimer's is a disease process that leads to dementia.

Hope this helps & best of luck!
Andrew D.
Content Manager, Next Step Test Prep.
lumosmaximus
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Joined: Sun Jan 07, 2018 1:05 am

Re: FL4 PSY/SOC Q31

Postby lumosmaximus » Sun Jan 07, 2018 1:12 am

Hello Andrew,

I just had a quick question about why neurofibrillary tangles and amyloid plaques can only be visualized via autopsy. This was mentioned in a khan academy video but there isn't a lot of discussion regarding visualizing them. Why can't traditional MRIs and CT scans be used? Please let me know when you get a chance.

Thank you!
NS_Tutor_Andrew
Site Admin
Posts: 286
Joined: Mon May 23, 2016 1:47 pm

Re: FL4 PSY/SOC Q31

Postby NS_Tutor_Andrew » Mon Jan 08, 2018 4:57 pm

Hi @lumosmaximus --

Excellent question! In a nutshell, CT and MRI aren't able to visualize abnormalities on the level of misformed proteins (which are really tiny and hard to distinguish from other structures). A full discussion of the physics of CT & MRI (as well as other imaging modalities like ultrasonography) and the implications thereof would go well beyond the scope of the MCAT, and to some extent is best postponed to med school or radiology residency, but as a quick note, Medscape has a short overview of Alzheimer disease imaging that can help give you a sense of what CT and MRI can and cannot do.

Interestingly, in the last 5-6 years, technology has emerged for imaging beta-amyloid plaques directly, via radioactive tracing. This actually hasn't quite lived up to researchers' hopes, because it turns out that many people without Alzheimer disease may also have beta-amyloid plaques. Thus, visualizing beta-amyloid plaques through these techniques is of questionable diagnostic utility. Assessing the diagnostic value of various tests is a surprisingly complex topic that involves specific statistical analyses as well as cost-benefit tradeoffs relating to the diagnostic modality itself. This is an area of medicine that I personally find to be very interesting, but it does go beyond the scope of the MCAT, so don't worry about it too much :).
Andrew D.
Content Manager, Next Step Test Prep.

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