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Aim: The cognitive impairment seen in Parkinson's disease (PD) results in patient disability and reduced quality of life. However, using cognitive screening scales specific to PD in routine clinical practice is difficult because of limited time, resources, and skills. We studied the ability of routine cognitive tests to differentiate between Parkinson's disease dementia (PDD) and PD and among the neuropsychological profiles of elderly individuals with PD, PDD, Alzheimer's disease (AD), and normal cognition. Methods: This cross-sectional study involved 124 subjects. Subjects were 35 cognitively normal elderly and 37 elderly individuals with PD, 22 with PDD, and 30 with AD. All subjects were diagnosed by a specialist using standard criteria. Clinically relevant data and scores from the Montreal Cognitive Assessment and the Thai Mental State Examination were collected. Cognitive test scores were compared among groups. Receiver operating characteristic curves were constructed for a range of cut-off points to explore the sensitivity and specificity of the screening tools to detect PDD. Results: There were 74 female subjects (59.7%), and the average age of all subjects was 75.6 years. The median score on the modified Hoehn and Yahr scale was 2.5 in subjects with PD and 4 in those with PDD (P < 0.001). The cut-offs for differentiating PDD from PD were 25 on the Thai Mental State Examination and 14 on the Montreal Cognitive Assessment. The sensitivity of the Thai Mental State Examination was 78.4%, and the specificity was 66.7% (area under the curve: 0.828). The sensitivity of the Montreal Cognitive Assessment was 81.1%, and the specificity was 75% (area under the curve: 0.876). There was a significant difference in the memory and language subdomains between AD and PDD (P < 0.05). Conclusions:The cut-offs used to differentiate PDD from PD were not the same as routine cut-offs in distinguishing AD from normal elderly. The cognitive profile deficit in PDD differed from that in AD. Interpretations of positive screenings test should take this finding into consideration.

<b><i>Background:</i></b> Various patterns of dementia care have been developed in different settings, depending on the availability of healthcare resources and facilities. The purpose of this study was to examine the epidemiology and characteristics of dementia care at a geriatric clinic, a field that has been subject to little prior evaluation. <b><i>Methods:</i></b> A retrospective chart review was undertaken of cohort patients with cognitive impairment who had received a diagnosis and were still on active follow-up at a geriatric clinic. A total of 892 patients were included. In addition, 203 geriatric patients with no cognitive impairment who attended the clinic during the study period were sampled as a control. <b><i>Results:</i></b> The main diagnoses of dementia were Alzheimer’s disease (AD) (40.1%), vascular dementia (16.9%), unspecified dementia (16.3%), mixed dementia (9.0%), AD with cerebrovascular disease (8.7%), and Parkinson’s disease dementia (6.1%). Atypical dementia was presented in 3.0% of cases. There were 178 patients with mild cognitive impairment, 20 with vascular cognitive impairment, and 18 with subjective cognitive decline. Other comorbidities were found in 97% of the subjects. Patients with cognitive impairment had a higher total number of other geriatric syndromes and higher percentages for delirium, falls, immobility, loss of appetite, and incontinence. Potentially reversible causes of dementia were found in 11.3% of the cases. Acetylcholinesterase inhibitors were administered to 61%, whereas 23.5% received an NMDA receptor antagonist. The need for a change in the antidementia medication was identified for 10.7% of the subjects; the major cause was adverse drug side effects. Nonpharmacological therapy only was administered to 52.4% of the people with dementia who had behavioral and psychological symptoms. <b><i>Conclusions:</i></b> Mixed brain pathologies, comorbidities, and the coexistence of other geriatric syndromes are common at geriatric clinics. Holistic, integrated, and continuous care are needed to improve the outcomes of patients with more complicated comorbidities.