Cognitive and behavioral symptoms in Parkinson's disease patients with the G2019S and R1441G mutations of the LRRK2 gene

• Mutations of the LRRK2 were associated with less subjective cognitive impairment.
• LRRK2-PD patients performed better on general cognition, attention and memory tests.
• Mild cognitive impairment and dementia was more frequent in idiopathic PD.
• Idiopathic Parkinson's disease patients presented more neuropsychiatric symptoms.
• There were no differences between carriers of the G2019S and the R1441G mutations.

ObjectiveTo compare the cognitive and psychiatric status of patients with Parkinson's disease related to the G2019S and the R1441G mutations of the LRRK2 gene (LRRK2-PD) and idiopathic Parkinson's disease (iPD) patients.MethodsWe examined cognition and psychiatric symptoms in 27 patients with LRRK2-PD (12 G2019S and 15 R1441G) and 27 iPD patients.ResultsThe groups were similar in age, education, disease duration, levodopa equivalent daily dose, and Unified Parkinson's Disease Rating Scale (UPDRS) II–IV; however, the LRRK2-PD showed less impairment on UPDRS-I (2.0 ± 1.7 vs. 4.2 ± 2.8, p = 0.003). The LRRK2-PD presented less frequent subjective cognitive complaints (18.5% vs. 63.0%, p = 0.002), and mild cognitive impairment or dementia (25.9% vs. 59.2%, p = 0.027). They also showed less impairment on scales for general cognition (Mattis dementia rating scale 131.2 ± 10.9 vs. 119 ± 24.0, p = 0.022), episodic verbal memory (Rey's auditory verbal learning test, immediate recall 39.2 ± 9.5 vs. 27.6 ± 12.8 p < 0.001, delayed recall 7.2 ± 3.7 vs. 4.7 ± 4.0 p = 0.022), and the Neuropsychiatric Inventory (9.7 ± 9.2 vs. 20.5 ± 14.3, p = 0.004, significant differences for apathy and hallucinations). The LRRK2-PD subjects were less frequently treated with antipsychotic medication (0% vs. 25.9%, p = 0.010). There were no significant differences between G2019S and R1441G mutation carriers.ConclusionsMutations of the LRRK2 gene might cause PD associated with less cognitive and neuropsychiatric impairment as compared to iPD.