RESEARCH ARTICLE Power spectra for screening parkinsonian patients for mild cognitive impairment Habib Bousleiman 1,2 , Ronan Zimmermann 1 , Shaheen Ahmed 1 , Martin Hardmeier 1 , Florian Hatz 1 Christian Schindler 2 , Volker Roth 3 , Ute Gschwandtner 1 & Peter Fuhr 1 1 Department of Neurology, Hospital of the University of Basel, Petersgraben 4, 4031 Basel, Switzerland 2 Swiss Tropical and Public Health Institute, University of Basel, Socinstrasse 57, 4051 Basel, Switzerland 3 Department of Mathematics and Computer Science, University of Basel, Bernoullistrasse 16, 4056 Basel, Switzerland Correspondence Peter Fuhr, Department of Neurology, Hospital of the University of Basel, Petersgraben 4, 4031 Basel, Switzerland. Tel: +41(0)612652525; Fax: +41(0)612655638; E-mail: peter.fuhr@usb.ch Funding Information This work was supported by the Swiss Parkinson’s Disease Association, the Gossweiler Foundation, the Freiwillige Akademische Gesellschaft Basel, and the Swiss National Science Foundation (SPUM 33CM30_140338). Received: 19 June 2014; Revised: 9 September 2014; Accepted: 15 September 2014 Annals of Clinical and Translational Neurology 2014; 1(11): 884–890 doi: 10.1002/acn3.129 Abstract Objective: Mild cognitive impairment in Parkinson’s disease (PD-MCI) is diag- nosed based on the results of a standardized set of cognitive tests. We investi- gate whether quantitative EEG (qEEG) measures could identify differences between cognitively normal PD (PD-CogNL) and PD-MCI patients. Methods: High-resolution EEG was recorded in 53 patients with Parkinson’s disease (PD). Relative power in five frequency bands was calculated globally and for ten regions. Peak and median frequencies were determined. qEEG results were compared between groups. Effect sizes of all variables were calculated. The best separating variable was used to demonstrate subject-wise classification. Results: Lower mean values were observed in global alpha1 power and alpha1 power in five brain regions (left hemisphere: frontal, central, temporal, occipital; right hemisphere: temporal, P < 0.05), differentiating between PD-CogNL and PD-MCI groups. Effect sizes were high, ranging from 0.79 to 0.87. Median fre- quency was 8.56 Æ 0.74 Hz and was not different between the groups. The var- iable with the best subject-wise classification was the power in the alpha1 band in the right temporal region. The area under the corresponding receiver operat- ing characteristic (ROC) curve was 0.72. The optimal classification threshold yielded a sensitivity of 65.9% and a specificity of 66.7%. The positive and nega- tive predictive values were 87.1% and 36.4%, respectively. Interpretation: Reduction in alpha1 band power in nondemented PD patients, particularly in the right temporal region, is highly indicative of MCI in PD patients. The results might be used to assist in time-efficient diagnosis of PD-MCI and avoid the drawbacks of test–retest effect in repeated neuropsychological testing. Introduction Cognitive and neuropsychiatric decline in patients with Parkinson’s disease (PD) are key determinants of the prognosis for survival and independence. 1,2 The assess- ment of the cognitive status of patients is done by carry- ing out a battery of neuropsychological tests. Mild cognitive impairment in PD patients (PD-MCI) differs from dementia by the fact that it does not interfere with daily activities. It is diagnosed by grouping the various tests into different cognitive domains (alertness, executive functions, visuo-spatial abilities, episodic, and working memory) and applying selection criteria on the outcome. 3 This is a lengthy process that is not widely available. It incurs high costs and relatively long waiting times that hinder repetition and adequate follow-up. Moreover, test– retest effects could bias the assessment of cognitive func- tions in repetitive clinical examinations. Quantitative electroencephalography (qEEG) might pres- ent itself as a potential alternative. Certain qEEG parame- ters were shown to be associated with dementia in patients with PD 4–9 or with Alzheimer’s disease. 9,10 For instance, Caviness et al. 8 identified an association between slowing of EEG rhythms and the cognitive state of PD patients, in particular in the theta and alpha frequency bands. Babiloni et al. 6 further discussed localized associations of brain 884 ª 2014 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals, Inc on behalf of American Neurological Association. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.