Cognitive impairment in preclinical Alzheimer's disease: A meta-analysis. —backman 2005

This is an audio summary of the article "Cognitive impairment in preclinical Alzheimer's disease: A meta-analysis." by Backman in 2005. A meta-analysis based on 47 studies with 9,097 controls and 1,207 preclinical Alzheimer's disease cases was carried out to estimate the extent of the cognitive impairment across several cognitive domains in preclinical Alzheimer's disease. There were significant preclinical abnormalities in linguistic ability, visuospatial skill, and attention; slightly lower losses in global cognitive ability, episodic memory, perceptual speed, and executive functioning; and no preclinical impairment in primary memory. Greater impact sizes were linked to younger ages ( 75 years) and shorter follow-up times ( 3 years) for both global cognitive function and episodic memory. Studies that employed population-based sampling produced greater effect sizes for global cognitive ability; studies that used pre-identified groups in terms of baseline cognitive impairment produced larger differences for episodic memory. The biggest effect sizes in episodic memory were produced by delayed testing and recall-based evaluation. The authors come to the conclusion that cognitive abnormalities across a number of categories are indicative of Alzheimer's disease years before a clinical diagnosis. Recent findings showing several brain structures and functions are damaged even before the Alzheimer's disease diagnosis are consistent with the broad nature of the loss. This is the end of this informational audio track on "Cognitive impairment in preclinical Alzheimer's disease: A meta-analysis." by Backman.

Bäckman, L., Jones, S., Berger, A.-K., Laukka, E. J., & Small, B. J. (2005). Cognitive impairment in preclinical Alzheimer’s disease: A meta-analysis. Neuropsychology, 19(4), 520–531. https://doi.org/10.1037/0894-4105.19.4.520