Global Deterioration Scale

The Global Deterioration Scale (GDS) is a seven-stage clinical staging instrument that locates an older adult along the continuum of cognitive decline, from no impairment through very severe dementia. Introduced by Barry Reisberg and colleagues in 1982, it was designed to give clinicians and researchers a shared, ordinally graded vocabulary for the natural history of primary degenerative dementia, most prominently Alzheimer's disease. Rather than producing a numeric test score, the GDS asks the assessor to match a patient's cognitive, functional, and behavioral picture — gathered through clinical interview and informant report — to one of seven prototypical stage descriptions. Stages 1 to 3 cover the spectrum from normal cognition through subjective and then mild objective decline, stage 4 marks the threshold of clinically diagnosable dementia, and stages 5 to 7 trace the progression through moderate, moderately severe, and severe disease toward total dependence. Because the stages are ordered and clinically anchored, the GDS supports tracking decline over time, communicating prognosis, and stratifying patients in trials and care planning. It remains one of the most widely used global staging tools in gerontology and is often paired with the companion FAST and BCRS instruments from the same group.