The neurologic syndrome of severe Alzheimer's disease. Relationship to functional decline

Abstract

Objective: To assess the possible association between functional decline and noncognitive neurologic signs in the severe stages of Alzheimer's disease (AD).

Design: Case series.

Setting: Subjects from a dementia research referral center, longitudinally followed, when necessary, into residential home and nursing home settings.

Patients: A consecutive sample of 56 patients (16 men, 40 women; mean age, 74.6 years) with a clinical diagnosis of probable AD in the moderately severe and severe stages.

Main outcome measure: For global dementia severity, the Global Deterioration Scale and Mini-Mental State examination; for functional assessment, the Functional Assessment Staging Scale; and for assessment of neurologic function, nine release signs (primitive reflexes), 10 measures of extrapyramidal function, and five measures of pyramidal function, including deep-tendon reflexes and plantar signs. Changes in activity or presence of neurologic signs were rated on a seven-point scale. Results were analyzed in terms of prevalence and magnitude of change in relation to functional impairment.

Results: Prevalence and mean scores of certain release signs, certain extrapyramidal measures commonly referred to as bradykinesia, and certain pyramidal signs showed significant associations with the magnitude of functional impairment. Other neurologic measures, for example, the palmomental reflex, and certain extrapyramidal measures commonly seen in Parkinson's disease, including the glabellar blink reflex, cogwheeling, tremor, shuffling gait, and festination, did not show significant increments with continuing functional decline in AD.

Conclusions: Functional decline in the advanced stages of AD appears to be associated with a particular combination of progressive cortical, extrapyramidal, and pyramidal system dysfunction. The characteristics of this neurologic syndrome of the severe stages of AD differ from those of other neurologic disorders. For example, the pattern of extrapyramidal system disease is different from that seen in Parkinson's disease. The neurologic syndrome of the severe stages of AD is amenable to description and deserves further investigation.