Ires Ghielen

44 Chapter 3 In the current study we aim to replicate the findings of Rutten et al. [18] in an independent sample of PD patients who were specifically referred for specialist neuropsychiatric evaluation. Using the same methodology in a different patient sample enables us to investigate the generalizability of the previous findings [20]. Methods Subjects The data used in this cross-sectional study were routinely collected at the Center for Neuropsychiatry in Parkinson’s disease (CNP) of the Amsterdam University medical center, location VUmc in Amsterdam, the Netherlands. The CNP is a specialized outpatient department for the diagnosis and treatment of PD patients experiencing neuropsychiatric symptoms. Patients are referred to the CNP by neurologists, general practitioners and specialists in geriatric medicine. Data of 176 patients were collected between April 2014 and February 2018. Patients were included if they were previously diagnosed with idiopathic Parkinson’s disease and provided written informed consent for their clinical data to be used in scientific research. Since several patients were included in both the previous and the current databases, we excluded overlapping patient data collected within five years after the data collection of Rutten et al. [18]. Measurements Clinical and demographic characteristics The Montreal Cognitive Assessment (MoCA) was used to screen the patient group for possible cognitive decline [21]. The United Parkinson Disease Rating Scale-III (UPDRS-III) score was used to assess the severity of motor symptoms [22]. The Beck Depression Inventory (BDI) was used to examine self-reported symptoms of depression [23]. The BDI cut-off score for clinically relevant symptoms of depression is 14 [24]. The patient’s history of psychiatric diagnoses was recorded as well as the psychiatric diagnoses given after the diagnostic examination, which was done by clinical evaluation by the assessing psychiatrists (OvdH/SR). Due to the time-frame in which data was collected, both the Diagnostic and Statistical Manual of Mental Disorders (DSM-)IV and the DSM-5 were used [25]. Patient sex, age, time since PD diagnosis (e.g. disease duration), and the use of dopaminergic medication (0 = no, 1 = yes) were recorded.