Occasional forgetting of objects, dates and situations is normal for people and occurs for various reasons such as a situation of stress or extreme tiredness, this situation is temporary, so it is not repeated in time linearly.
On the other hand we see that Alzheimer's disease (AD), also called senile dementia of Alzheimer's type (DSTA) or simply Alzheimer's, is a neurodegenerative disease that manifests as cognitive impairment and behavioral disorders. Characterized in its typical form by a loss of immediate memory and other mental abilities (such as higher cognitive abilities), as nerve cells (neurons) die and different brain areas atrophy, this is an irreversible process .
During presentations, speakers show their prowess by knowing the content well.
I think this word best fits the sentence. Prowess is about an ability of the person and based on the sentence the speakers try to prove something about understanding the content.