No, not always. Some aspects of cognitive function, specifically crystallized intelligence, are unaffected by AAMCD.
The term "crystallized intelligence" refers to abilities and knowledge accumulated over time (i.e., language and historical information). In contrast, “fluid intelligence” refers to the ability to solve new problems without drawing on prior knowledge (e.g.., solving puzzles and complex math problems).
It should be no surprise that crystallized intelligence rises steadily throughout life, reaching a plateau at around 80 years old. On the other hand, as a person ages, fluid intelligence—specifically, processing speed and working memory—declines steadily.[1]