Background: There is increasing evidence to suggest a tight relationship between cognitive impairment and falls in Parkinson's disease (PD). Here, we draw attention to a potentially significant flaw in the existent falls-related research, namely the apparent exclusion of patients with cognitive impairment or dementia. Objective: Our objective was to review all published, ongoing or scheduled fall-related intervention studies, in order to investigate the extent to which cognitively impaired individuals with PD were included in these studies. Methods: We analyzed published controlled trials regarding falls and PD in commonly used databases, as well as relevant ongoing clinical trials registered within the World Health Organization database, clinicaltrials.gov and the European Clinical Trials Database. Results: Fourteen of the fifteen published studies included had explicit cognitive exclusion criteria as part of their study protocol. Most of the 54 ongoing PD fall-related studies excluded patients with cognitive impairment. Conclusions: This suggests that individuals with cognitive impairment or dementia are excluded from fall-related research studies. We strongly recommend that future work in this area should include a representative sample of patients with PD, including subjects with cognitive decline.