The role of the motor subtypes on the relationship between anxiety and cognitive dysfunctions in Parkinson’s disease

Anxiety is a common neuropsychiatric symptom in Parkinson’s disease (PD). Until now, anxiety has been consistently related to cognitive deficits and severity of motor symptoms, whereas the association between anxiety and motor subtypes (TD-PD, tremor dominant and PIGD-PD, postural instability/gait disturbances dominant) revealed contrasting results. The present study aims to investigate the relationship between PD motor subtypes and anxiety and to explore whether the relationship between anxiety and cognitive deficits occurs in a specific PD motor subtype. Consecutive PD outpatients were recruited and divided into TD-PD and PIGD-PD groups according to Jankovic et al.’s criteria. All participants underwent a neuropsychological battery to evaluate anxiety, apathy, the global cognitive functioning, memory abilities, executive and visuo-constructional functions. Thirty-six patients with TD-PD and 35 patients with PIGD-PD were enrolled. The two groups did not differ on demographical and clinical variables. As for the severity of anxiety, no significant difference between the two groups was found. Regression analysis revealed that higher anxiety score was associated with poorer performance on constructional visuospatial test in both TD-PD and PIGD-PD. Clinical variables were not associated with anxiety in the two groups. Our findings indicated that the severity of anxiety was not associated with any PD motor subtypes. Moreover, regression analysis revealed that impaired visuo-constructional abilities are related to anxiety independently of PD motor subtypes. Since altered fronto-parietal network might be one of the pathogenetic mechanisms underpinning anxiety and constructional visuospatial deficits, the treatment of cognitive dysfunctions might reduce anxious symptoms.