Primary dementia care based on the individual needs of the patient: study protocol of the cluster randomized controlled trial, DemStepCare oleh Isabella Bablok, Harald Binder, Dominikus Stelzer, Klaus Kaier, Erika Graf, Julian Wangler, Michael Jansky, Michael Löhr, Michael Schulz, Marie Kockläuner, Katharina Geschke, Alexandra Wuttke-Linnemann, Andreas Fellgiebel, Erik Farin, study group DemStepCare