Study Title:

Memory after Silent Stroke: Hippocampus and Infarcts both Matter

Study Abstract

Objective: Memory decline commonly occurs among elderly individuals. This observation is often attributed to early neurodegenerative changes in the hippocampus and related brain regions. However, the contribution of vascular lesions, such as brain infarcts, to hippocampal integrity and age-associated memory decline remains unclear.

Methods: We studied 658 elderly participants without dementia from a prospective, community-based study on aging and dementia who received high-resolution structural MRI. Cortical and subcortical infarcts were identified, and hippocampal and relative brain volumes were calculated following standard protocols. Summary scores reflecting performance on tasks of memory, language, processing speed, and visuospatial function were derived from a comprehensive neuropsychological battery. We used multiple regression analyses to relate cortical and subcortical infarcts, hippocampal and relative brain volume, to measures of cognitive performance in domains of memory, language, processing speed, and visuospatial ability.

Results: Presence of brain infarcts was associated with a smaller hippocampus. Smaller hippocampus volume was associated with poorer memory specifically. Brain infarcts were associated with poorer memory and cognitive performance in all other domains, which was independent of hippocampus volume.

Conclusions: Both hippocampal volume and brain infarcts independently contribute to memory performance in elderly individuals without dementia. Given that age-associated neurodegenerative conditions, such as Alzheimer disease, are defined primarily by impairment in memory, these findings have clinical implications for prevention and for identification of pathogenic factors associated with disease symptomatology.

From press release:

New research links 'silent strokes,' or small spots of dead brain cells, found in about one out of four older adults to memory loss in the elderly. The study is published in the January 3, 2012, print issue of Neurology®, the medical journal of the American Academy of Neurology.


"The new aspect of this study of memory loss in the elderly is that it examines silent strokes and hippocampal shrinkage simultaneously," said study author Adam M. Brickman, PhD, of the Taub Institute for Research on Alzheimer's Disease and the Aging Brain at Columbia University Medical Center in New York.

For the study, a group of 658 people ages 65 and older and free of dementia were given MRI brain scans. Participants also underwent tests that measured their memory, language, speed at processing information and visual perception. A total of 174 of the participants had silent strokes.

The study found people with silent strokes scored somewhat worse on memory tests than those without silent strokes. This was true whether or not people had a small hippocampus, which is the memory center of the brain.

"Given that conditions like Alzheimer's disease are defined mainly by memory problems, our results may lead to further insight into what causes symptoms and the development of new interventions for prevention. Since silent strokes and the volume of the hippocampus appeared to be associated with memory loss separately in our study, our results also support stroke prevention as a means for staving off memory problems," said Brickman.

Study Information

Blum, S., MD, PhD, Luchsinger, J.A., MD, MPH, Manly, J.J., Schupf, N., Stern, Y., Brown, T.R., DeCarli, C., Small, S.A., Mayeux, R., Brickman, A.M..
Memory after Silent Stroke: Hippocampus and Infarcts both Matter
Neurology
2012 January
Taub Institute for Research on Alzheimer's Disease and the Aging Brain at Columbia University Medical Center in New York

Full Study