We come from a religious background where treatment is based on faith and home cures. What can we use to treat pick disease?

More info needed. Fo you mean newman-pick or pick's disease. They are different.
Proven vs unproven. By definition, "alternative" is different than modern western medicine. Generally any drug, herb, treatment, or procedure that stands up to rigorous scientific scrutiny is included in modern medicine. The problem is that many alternative practices, herbs etc do not stand up to scientific scrutiny and cannot be shown to work. They therefore remain "alternative". Soup may comfort but not cure.
Autonomy. I am going to assume that this is an adult who has frontotemporal dementia, and he/she has is agreeable to this. We have little to offer these patients, and the advantages of having a loving home like yours are really not offset by any disadvantage of non-physician-based care. When one of you becomes ill with something treatable, i hope ull find common ground between science & faith as do we all.