[dta5003]

Yes, because there are more factors than the treatment itself, and it is important to be able to ascribe benefit/harm to the treatment vs. the other factors.

As mentioned in another comment, the sad state of Alzheimers patient care today includes infrequent attention. It is plausible that two visits from another human each day would in itself cause the same kind of improvement seen in the study.

Without a control group, it is impossible to ascribe the results to the treatment or the other aspects of the study.