The goal of this observational study is to evaluate the relationship between GBA mutation and cognitive stimulation treatment response in patients with Parkinson's disease. The main questions it aim to answer are: • assess whether the GBA mutation is associated with greater or lesser response to cognitive training treatment compared to a control group of PD patients without genetic mutations. • investigate the effect of cognitive stimulation program on behavioural aspects as secondary consequence induced by the possible improvement of cognitive abilities following treatment. Participants will be undergo to: - a neuropsychological evaluation describing their cognitive profile; - a genetic investigation and finally included in a cognitive stimulation programs according to regular clinical practice. Researchers will compare PD patients with GBA mutation and patients without genetic mutation to evaluate the effectiveness of cognitive stimulation treatment.