Withdrawal, apathy and lack of vigor in late life depression : factorial validity and relationship to diagnosis

Withdrawal, apathy and lack of vigor (WAV) describe a pattern of lack of vitality and dropping of interests and activities in later life, which may or may not indicate depression. This study examines (a) whether the Geriatric Depression Scale (GDS) contains a measure of this symptom cluster, and if so, (b) whether the presence of WAV leads to more false positive predictions by the GDS. A total of 444 Chinese older persons responded to the GDS and the Mini- Mental State Examination (MMSE), and were independently assessed by psychiatrists for depression and other diagnoses. Confirmatory factor analysis showed that six WAV symptoms formed a distinct cluster on the GDS. WAV was positively correlated with age and MMSE but most other symptom clusters measured on the GDS were not. Nonetheless, the ROC curves were essentially the same, regardless of whether the WAV items were included or not. Further analysis revealed that the optimal cutoff for the GDS without WAV produced fewer false positives, but also missed more true cases, than the full scale. The extent to which false positives become an issue depends on the specific threshold chosen (which entails a tradeoff with sensitivity) rather than the presence of WAV items.