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Reliability and validity of the Geriatric Depression Scale in depression in Parkinson’s disease
  1. F S Ertan1,
  2. T Ertan2,
  3. G Kızıltan1,
  4. H Uyguçgil3
  1. 1Department of Neurology, Istanbul University Cerrahpaşa Medical School, Istanbul, Turkey
  2. 2Department of Psychiatry, Section of Geriatric Psychiatry, Istanbul University Cerrahpaşa Medical School, Istanbul, Turkey
  3. 3Department of Neurology, Vehbi Koç Foundation, American Hospital, Istanbul, Turkey
  1. Correspondence to:
 Dr F S Ertan
 Department of Neurology, Istanbul University Cerrahpaşa Medical School, Aksaray 34303 Istanbul, Turkey;


The objective of this study was to investigate reliability and validity of the self rated 30 item Geriatric Depression Scale (GDS) in screening and diagnosis of depression in Parkinson’s disease (PD). The study sample comprised 109 non-demented patients with PD admitted to the movement disorders outpatient unit. The reference diagnosis of depression was made according to DSM-IV criteria. Discriminant validity and internal consistency of the total scale were studied. Sensitivity, specificity, and positive and negative predictive values (PPV and NPV) were calculated for different cutoff scores. Receiver operating characteristics (ROC) analysis was also carried out. The sample comprised 56 patients with and 53 without depression. In the discriminant validity analysis, the mean total GDS score of subjects with depression was significantly higher compared with those without depression. The Cronbach’s α score was 0.92 and the split half correlation coefficient 0.91. The cutoff score of 13/14 provided the highest sum of sensitivity and specificity level. The sensitivity of this cutoff score was 0.78 and specificity 0.85, while PPV was 0.84 and NPV 0.79. The area under the curve value in the ROC analysis was 0.891. Sensitivity and specificity analysis showed that cutoff scores of 8/9 or 9/10 could be useful for screening and 14/15 or 15/16 for diagnostic purposes. This study showed that the 30 item GDS, with its high discriminant validity, internal consistency, and reasonably clear cutoff scores, could be a useful screening or diagnostic self rated depression scale in patients with PD.

  • AUC, area under the curve
  • BDI, The Beck Depression Inventory
  • DSM-IV, Diagnostic and statistical manual of mental disorders, 4th edition
  • GDS, Geriatric Depression Scale
  • HY, Hoehn and Yahr Scale
  • NPV, negative predictive value
  • PPV, positive predictive value
  • UPDRS, Unified Parkinson’s Disease Rating Scale
  • assessment scale
  • depression
  • Parkinson’s Disease

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  • Competing interests: none of the authors had any financial or other interest from any institution for this study.