Christian Núñez1,2, Antonio Callén1,2, Federica Lombardini1,2, Yaroslau Compta3,4,5, Christian Stephan-Otto1,2,6. 1. Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Barcelona, Spain. 2. Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Spain. 3. Parkinson's Disease & Movement Disorders Unit, Neurology Service, Hospital Clínic de Barcelona & Maria de Maeztu Excellence Center Institute of Neuroscience, University of Barcelona, Barcelona, Spain. 4. Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), Barcelona, Spain. 5. Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED: CB06/05/0018-ISCIII), Barcelona, Spain. 6. Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain.
Abstract
OBJECTIVE: The study of cortical gyrification in Alzheimer's disease (AD) could help to further understanding of the changes undergone in the brain during neurodegeneration. Here, we aimed to study brain gyrification differences between healthy controls (HC), mild cognitive impairment (MCI) patients, and AD patients, and explore how cerebral gyrification patterns were associated with memory and other cognitive functions. METHODS: We applied surface-based morphometry techniques in 2 large, independent cross-sectional samples, obtained from the Alzheimer's Disease Neuroimaging Initiative project. Both samples, encompassing a total of 1,270 participants, were analyzed independently. RESULTS: Unexpectedly, we found that AD patients presented a more gyrificated entorhinal cortex than HC. Conversely, the insular cortex of AD patients was hypogyrificated. A decrease in the gyrification of the insular cortex was also found in older HC participants as compared with younger HC, which argues against the specificity of this finding in AD. However, an increased degree of folding of the insular cortex was specifically associated with better memory function and semantic fluency, only in AD patients. Overall, MCI patients presented an intermediate gyrification pattern. All these findings were consistently observed in the two samples. INTERPRETATION: The marked atrophy of the medial temporal lobe observed in AD patients may explain the increased folding of the entorhinal cortex. We additionally speculate regarding alternative mechanisms that may also alter its folding. The association between increased gyrification of the insular cortex and memory function, specifically observed in AD, could be suggestive of compensatory mechanisms to overcome the loss of memory function. ANN NEUROL 2020 ANN NEUROL 2020;88:67-80.
OBJECTIVE: The study of cortical gyrification in Alzheimer's disease (AD) could help to further understanding of the changes undergone in the brain during neurodegeneration. Here, we aimed to study brain gyrification differences between healthy controls (HC), mild cognitive impairment (MCI) patients, and ADpatients, and explore how cerebral gyrification patterns were associated with memory and other cognitive functions. METHODS: We applied surface-based morphometry techniques in 2 large, independent cross-sectional samples, obtained from the Alzheimer's Disease Neuroimaging Initiative project. Both samples, encompassing a total of 1,270 participants, were analyzed independently. RESULTS: Unexpectedly, we found that ADpatients presented a more gyrificated entorhinal cortex than HC. Conversely, the insular cortex of ADpatients was hypogyrificated. A decrease in the gyrification of the insular cortex was also found in older HC participants as compared with younger HC, which argues against the specificity of this finding in AD. However, an increased degree of folding of the insular cortex was specifically associated with better memory function and semantic fluency, only in ADpatients. Overall, MCI patients presented an intermediate gyrification pattern. All these findings were consistently observed in the two samples. INTERPRETATION: The marked atrophy of the medial temporal lobe observed in ADpatients may explain the increased folding of the entorhinal cortex. We additionally speculate regarding alternative mechanisms that may also alter its folding. The association between increased gyrification of the insular cortex and memory function, specifically observed in AD, could be suggestive of compensatory mechanisms to overcome the loss of memory function. ANN NEUROL 2020 ANN NEUROL 2020;88:67-80.