Global Deterioration Scale for Assessment of Primary Degenerative Dementia (GDS)
What it measures:
The Global Deterioration Scale (GDS) is a screening tool that helps caregivers/health care professionals determine the status of a patient’s primary dementia, with regard to the progression of their disease, as well as to determine a patient’s future expectations based on their current cognitive status. A categorical table classifies patients in specific stages of dementia. There are 7 stages incorporated into the GDS. Stage 1 on the scale is “no cognitive decline,” while Stage 7 on the scale is “very severe cognitive decline.” Each stage reflects upon an individual patient’s cognitive decline, based on several clinical characteristics and psychometric concomitants. Instead of assigning patients a numerical score, a clinician compares an individual based on their cognition and function to the criteria on the GDS, and uses their best judgement to choose the most appropriate stage. (1)
To establish a quick and more concise screening tool to detect early onset of dementia as well as the severity of the condition, the Modified GDS was created by using 5 individual items from the 7 GDS stages. There are 31 items on the GDS questionnaire that are used to assess a patient’s cognitive status, and 5 of the items were found to be the best predictors of dementia, referred to as Stage 20, 30, 8, 25, and 31 in this study. These are not to be confused with the original GDS stages 1-7. The Modified GDS was found to be just as effective as the full GDS 31 questionnaire in screening for dementia. The Modified GDS is used as a quick screening tool to detect the early onset of dementia as well as the severity of the condition. Before this tool is approved for clinical use, further psychometric testing is necessary. (2)
This summary contains information on use of this test in patients with primary progressive dementia, including Alzheimer disease. Included is information for the original GDS and for the Modified GDS.
In our opinion, the GDS can be used in the physical therapy setting for evaluating the severity of patients who are already diagnosed with dementia. Using this assessment tool can help us understand what stage of dementia the patient is in and what signs/symptoms to expect when working with an individual. This can help us determine the best plan of care for the patient, and help us think of appropriate interventions with regard to the patient’s presenting symptoms to maximize the effectiveness of treatments used. This tool also may help us to educate the patient’s family or caregiver regarding the symptoms to expect, based on the patient GDS classification stage. This is important for the family to ensure the patient’s safety and for prevention of safety, especially as the disease progresses over time.
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