Its pretty easy to check someone's publication record, simply look them up on Pubmed which is the publicly available database of all published academic journals in the bio-medical sciences. It doesn't have every single journal but those that are not available via Pubmed are known as "unlisted" and not usually given the same authority as a listed journal.
A quick search, and I mean this took about 3 minutes, search turns up 2 publications by a DS Khalsa, one that mentions Alzheimers and the Alzheimer's Prevention Foundation, and one that does not. Here's the url for the search on the term "Khalsa D S" http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed. (If that doesn't work, the search engine is at www.pubmed.com and I used two search terms "Khalsa D S" and "Khalsa alzheimer's"). Neither appear to be clinical trials or original research but I have not read the papers in full and therefore cannot tell for certain. The first, published in 1985, appears to be a summary of evidence, a review in other words and the second one published in 1998 is classified by Pubmed as a review.
So, the author cited here has a publication record but on an initial search it appears to be short one. The results of that search suggest that he has not published original research in the field in a Pubmed listed journal. To be sure of that one would either have to spend much longer conducting far more extensive literature searches or simply contact him and ask.