Alzheimer's Disease: The Downside of a Highly Evolved Parietal Lobe? - Journal of Alzheimer's Disease - IOS Press

Alzheimer's Disease: The Downside of a Highly Evolved Parietal Lobe? - Journal of Alzheimer's Disease - IOS Press

Journal Article

	Alzheimer's Disease: The Downside of a Highly Evolved Parietal Lobe? Journal Journal of Alzheimer's Disease Publisher IOS Press ISSN 1387-2877 (Print) 1875-8908 (Online) Subject Medicine, Clinical Neurology and Internal Medicine Category Hypothesis Pages - DOI 10.3233/JAD-122299 Subject Group Medicine and Health Publisher's Copyright Statement	Add to marked items Add to shopping cart Add to saved items Recommend this article

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Authors

Emiliano Bruner¹, Heidi I.L. Jacobs²

¹Centro Nacional de Investigación sobre la Evolución Humana, Burgos, Spain
²Cognitive Neuroscience, Institute of Neuroscience and Medicine-3, Research Centre Jülich, Jülich, Germany

Abstract

Clinical grade Alzheimer's disease (AD) is only described in humans. Recent imaging studies in early AD patients showed that the parietal areas display the most prominent metabolic impairments. So far, neuroimaging studies have not been able to explain why the medial parietal regions possess this hub characteristic in AD. Paleoneurological and neuroanatomical studies suggest that our species, Homo sapiens, has a unique and derived organization of the parietal areas, which are involved in higher cognitive functions. Combining evidence from neuroimaging, paleontology, and comparative anatomy, we suggest that the vulnerability of the parietal lobe to neurodegenerative processes may be associated with the origin of our species. The species-specific parietal morphology in modern humans largely influenced the brain spatial organization, and it involved changes in vascularization and energy management, which may underlie the sensitivity of these areas to metabolic impairment. Metabolic constraints and anatomical evolutionary changes in the medial parietal regions of modern humans may be important in early AD onset. Taking into account the species-specific adaptations of the modern human parietal areas and their association with AD, we hypothesize that AD can be the evolutionary drawback of the specialized structure of our parietal lobes. The cognitive advantage is associated with increased sensitivity to neurodegenerative processes which, being limited to the post-reproductive period, have a minor effect on the overall genetic fitness. The changes of energy requirements associated with form and size variations at the parietal areas may support the hypothesis of AD as a metabolic syndrome.