Findings from the long-running Religious Orders Study, from 354 Catholic nuns and priests who were given annual cognitive tests for up to 13 years before having their brains examined post-mortem, has revealed that even the very early cognitive impairments we regard as normal in aging are associated with dementia pathology. Although pathology in the form of neurofibrillary tangles, Lewy bodies, and cerebral infarctions were all associated with rapid decline, they were also associated with “normal” mild impairment. In the absence of any of these lesions, there was almost no cognitive decline.
Previous research has shown that white matter lesions are very common in older adults, and mild cognitive impairment is more likely in those with quickly growing white matter lesions; importantly, the crucial factor appears to be the rate of growth, not the amount of lesions. This new study extends the finding, suggesting that any age-related cognitive impairment reflects the sort of brain pathology that ultimately leads to dementia (if given enough time). It suggests that we should be more proactive in fighting such damage, instead of simply regarding it as normal.
(2010). Neurodegenerative basis of age-related cognitive decline.
Neurology. 75(12), 1070 - 1078.
(2010). Cognitive activity and the cognitive morbidity of Alzheimer disease.
Neurology. 75(11), 990 - 996.