Based on the mental health information and according to the textbook, the part of the brain which has not been implicated in major neurocognitive disorders is a beta-amyloid protein.
Currently, it has only been assumed that beta-amyloid protein affects affect cognition.
However, at the moment, beta-amyloid protein has not separately been examined biochemically and then evaluated to know its effects on the cognitive process.
In contrast, the other options have been found to impact neurocognitive disorders significantly.
Hence, in this case, it is concluded ty the correct answer is option A. "beta-amyloid protein."
Learn more about neurocognitive disorders here: https://brainly.com/question/7304756
