Psychometric data on the Geriatric Depression Scale: Short Form (GDS: SF) vary. Yesavage and Sheikh, who in 1986 developed the GDS: SF by selecting 15 questions from the long form, that year conducted a small validation study using 35 people ages 55 and older (18 in the community and 17 in treatment settings for depression) to compare the two forms.1 The authors found that "both forms were successful in differentiating depressed from nondepressed adults with a high correlation (r = 0.84, P < 0.001)."1 Lyness and colleagues, in a 1997 study of 130 primary care outpatients ages 60 years and older found that the GDS: SF had a 92% sensitivity and an 81% specificity when using a cutoff score of 5.2 And a 2005 study by Friedman and colleagues examined the GDS: SF using 960 "functionally impaired, cognitively intact, community-dwelling older primary care patients in the United States."3 They found moderate internal consistency reliability (with a Cronbach [alpha] coefficient of 0.749); good construct validity, with significant associations between the GDS: SF and measures of depressed mood and life satisfaction; a sensitivity of 81.45% with a cutoff score of 6 and 89.5% with a cutoff score of 5; and specificity of 75.36% with a cutoff score of 6 and 65.3% with a cutoff score of 5.

Special populations. Limited work has been done on the GDS: SF in screening for depression in older adults with Alzheimer disease, chronic pain, heart disease, diabetes, and other chronic or degenerative conditions that afflict older adults and may affect mood. The tool's use with adults who have Parkinson disease has, however, been examined in several studies. One compared the psychometric properties of the GDS: SF and the Hamilton Depression Rating Scale in 148 outpatients with Parkinson disease.4 Thirty-two subjects (22%) were diagnosed with a depressive disorder. While the Hamilton Depression Rating Scale, designed to rate severity of symptoms in patients already diagnosed with depression, provided a more comprehensive evaluation of depressive symptoms, the GDS: SF identified critical symptoms of depression in those with Parkinson disease.

A literature review of 45 studies of depression and Parkinson disease from 1922 through 1998 found that 31% of people with the disease experience depression at some point.5 In older adults with Parkinson disease, depression negatively affects function,6 quality of life,7 caregiver well-being,8 and cognition.9 But depression in patients with Parkinson disease may be underrecognized and too rarely treated.10, 11 Because the GDS: SF is a brief instrument and can be self-administered, it's useful in distinguishing depressed from nondepressed older adults in this population.

Sherry A. Greenberg, MSN, APR N, B C, GNP

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