PrepTest 137

Incorrect. This answer is too definitive in saying that "anyone" prone to brain injury will get Alzheimer's. While susceptibility to brain injury makes one susceptible to Alzheimer's that's about risk, not certainty.

Incorrect. This answer is too strong in saying that beta-amyloid "entirely" determines Alzheimer's risk. The stimulus even notes another factor—brain injury.

Incorrect. This answer reverses the causality—lowered testosterone can contribute to Alzheimer's but that doesn't indicate that Alzheimer's will lower testosterone levels.

Incorrect. This answer is too strong and a reversal. While brain injury can contribute to Alzheimer's, a risk of Alzheimer's doesn't determine who is at risk of brain injury. Pretty much anyone is at risk of brain injury from falls!

Correct. Argument or Facts:
Facts

Question Type:
Argument Completion

Stimulus Summary:
Testosterone effects - Protect brain, reduce beta-amyloid
Brain injury and beta-amyloid effects - Alzheimer's
Therefore - __________

Answer Anticipation:
There's a lot of causal language throughout this stimulus, bringing up two effects of testosterone. These effects themselves are noted as being causally related to Alzheimer's disease. And, much like conditional statements, we can "chain" causal statements together. Unlike conditional statements, however, we can generally infer that removing a cause should also lower risk of the effect (which would be an illegal negation in a conditional statement).

So here, since beta-amyloid and brain injury both contribute to Alzheimer's, removing or reducing them should lower Alzheimer's risk. And testosterone is shown to reduce both of them. Putting these statements together, we can conclude that testosterone should lower Alzheimer's risk, and thus lower testosterone levels can contribute to Alzheimer's risk. Let's find one of those two in the answer choices!

Answer Explanation:
The argument establishes a causal relationship between testosterone and risk factors for Alzheimer's. Thus, lowering testosterone should increase those risk factors, thus increasing Alzheimer's risk.

Key Takeaway:
Causal statements can be chained together much like conditional statements. However, unlike conditional statements, causal statements can also lead to negation inferences—removing a cause should have some impact on the presence of the effect.