[Screening of executive functions in patients with Parkinson's disease using the new rapid test PAL-5]

Parkinson's disease (PD) is the second most prevalent chronic neurodegenerative disorder worldwide, following Alzheimer's disease. Along with the characteristic motor symptoms of the disorder, especially bradykinesia, cognitive deficits can often be found prior to the onset of the disorder. These mainly concern executive functioning. To detect cognitive deficits at an early stage, initial screening procedures are recommended. The new cognitive rapid test Paarassoziationslernen-5 ("PAL-5") has been developed to detect the most prevalent cognitive symptoms - namely executive impairments - of PD patients. It consists of a direct recall of five incompatible and newly jointed word pairs (capitals vs. countries), an intermediate formal lexical word fluency task ("FAS-Test") and a delayed recall. Thereby, the three major executive functioning processes are tested: cognitive flexibility, inhibition and memory. In the department of neurology of the University Clinic of Cologne, the PAL-5 was completed by 154 PD patients, 115 participants with cognitive deficits without a PD diagnosis and 115 controls (N = 384) between 2014 and 2016. For purposes of retest reliability determination, another 42 controls were examined from February to July 2017, with a four-month time interval between the initial and second test. Highly significant group differences have been found. PD patients and cognitive impaired participants scored significantly lower than the control group. A comparison of PD patients and cognitively impaired participants did not reveal significant group differences. Additionally, a moderate to high correlation between PAL-5 and MMST as well as PAL-5 and PANDA was found (respectively p < .001). An ROC analysis of the PAL-5 total score of PD patients with a score lower than 11 showed an AUC of .91. Therefore, a cut-off of ≤ 10 seems to be practicable to detect cognitive deficits - especially executive functioning deficits and memory impairments - in PD patients. It has been shown that cognitive flexibility, inhibition and memory is a short useful combination for a screening procedure of PD patients.