Based on the information given, it should be noted that the method of data collection that would be most appropriate in this case is experimental research.
An experimental research simply means the study that adheres to the scientific research design. It consists of a hypothesis that can be manipulated by the researcher and variables which can be measured and compared.
Since the researcher wants to study of the effects of new drug intended to treat Dementia, the appropriate method is an experimental research.
Learn more about researches on:
https://brainly.com/question/25851216
