Lifetime of knowledge can clutter memories of older adults. When a person tries to access a memory, their brain quickly sifts through everything stored in it to find the relevant information. But as we age, many of us have difficulty retrieving memories. Researchers propose an explanation for why this might be happening: the brains of older adults allocate more space to accumulated knowledge and have more material to navigate when attempting to access memories. While this wealth of prior knowledge can make memory retrieval challenging, the researchers say it has its upsides -- this life experience can aid with creativity and decision-making. Source 9y.
Older people may take a longer time to think for multiple reasons. One reason could be that a older person is experiencing neurodegeneration. Accumulated stress from previous life events can also break down cognitive functions overtime. Older people may be noticing more about how a conversation is proceeding or may be trying to formulate the best response to the question that is asked of them. It really depends upon the person and the sum of the things that have contributed to who they are…