The diseases FTD and DLBD belong to the spectrum of diseases called Parkinson's Plus, as they include symptoms and signs typical of Parkinson's disease, but also other, non-Parkinsonian symptoms and signs, which are characteristic of each of the diseases in the group. Leg tremors, for example, can appear as part of the parkinsonian symptoms in any of these diseases.

Dr. Oren Cohen, Parkinson's and Movement Disorders Clinic, Sheba Medical Center, Tel Hashomer (from the Questions for Doctors forum, the old website)