What Most Causes Cognitive Decline Is Not What We’ve Been Looking For

Health

 

Jonathan Silver, MD Reviewing Boyle PA et al., Ann Neurol 2013 Sep 74:478The most common factors are not the common degenerative diseases.
When evaluating patients with cognitive decline, we usually focus on common disorders, such as cerebrovascular disease, Alzheimer disease, and Lewy body disease. This analysis of data on 856 deceased participants from two longitudinal, clinicopathological studies of aging and dementia provides information on the causes of cognitive decline.The participants had been evaluated regularly since 1994 or 1997; mean age at death was 88. The authors examined the rate and timing of cognitive decline and linked these to the three age-related pathologies. Alzheimer pathology explained 22% of the decline, gross infarcts 2%, and Lewy bodies 8%. When considered together, these were associated with a faster rate of cognitive decline, but accounted for only 41% of the variation in decline. The researchers also compared pathology findings during terminal cognitive decline (which has a steep slope) and the period before the onset of terminal cognitive decline. The pathology findings together accounted for only 25% of the variation in onset of terminal decline, and 32% of preterminal decline.

COMMENT

This study demonstrates that most (59%) of the determining factors for cognitive decline are not the common degenerative diseases. Although these diseases are important, other factors evidently exist that need further research. Even such factors as glucose regulation within the normal range might influence cognitive decline (NEJM JW Psychiatry Nov 1 2013). The study findings also open the possibility that interventions (diet, exercise, glucose control) can modify the risk for decline.

EDITOR DISCLOSURES AT TIME OF PUBLICATION

Disclosures for Jonathan Silver, MD at time of publication Editorial boards Journal of Neurology, Neurosurgery and Psychiatry; Journal of Neuropsychiatry and Clinical Neuroscience; UpToDate Leadership positions in professional societiesNorth American Brain Injury Association (Board Member) Editorial Boards Journal of Neurology, Neurosurgery & Psychiatry; Journal of Neuropsychiatry and Clinical Neurosciences

CITATION(S):

  1. Boyle PA et al. Much of late life cognitive decline is not due to common neurodegenerative pathologies. Ann Neurol 2013 Sep; 74:478. (http://dx.doi.org/10.1002/ana.23964)