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Hippocampal volume and shape features in superagers
Author(s) -
Cobia Derin,
Paxton Holly,
Sridhar Jaiashre,
MakowskiWoidan Beth,
Engelmeyer Janessa,
Weintraub Sandra,
Mesulam Marsel,
Rogalski Emily J
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.045234
Subject(s) - context (archaeology) , hippocampal formation , analysis of variance , cognition , episodic memory , repeated measures design , age groups , psychology , audiology , lateralization of brain function , medicine , normative , demography , neuroscience , mathematics , paleontology , philosophy , statistics , epistemology , sociology , biology
Background Interest in factors contributing to superior cognitive aging has increased in recent years with the study of “SuperAgers” – individuals over age 80 with episodic memory performance similar to average middle‐aged adults. Given hippocampal involvement in memory formation, this project aimed to assess the integrity of this structure in the context of “SuperAging.” Method Participants included 67 SuperAgers (SA), 28 cognitively average 80+ year‐old cognitively average normal controls (O‐NC) and 25 middle‐aged cognitively average controls (MA‐NC). SA were age > 80 with memory performance at or above normative values for individuals 50‐60 years of age and other cognitive scores normal for age. Control groups scored within the average range for age and education on all cognitive domains. Volume and shape of bilateral hippocampi in each participant was estimated using high‐dimensional surface mapping. Comparisons between groups included the use of repeated measure GLM designs. Result No significant effect for hippocampal volume by group (SA: left=2006.33, right=2550.02; O‐NC: left=2017.25, right=2537.94; MA‐NC: left=2208.98, right=2589.70; F 117,2 =1.453 p =0.23), but a significant hemispheric effect (Right>Left; F 117,1 =632.40, p <0.001) and group x hemisphere effect ( F 117,2 =6.65, p =0.002). Shape models revealed a significant difference among groups in left ( F 216,20 =9.23, p <0.001) and right ( F 216,20 =1.81, p =0.02) hippocampal shape. Follow‐up ANOVAs revealed this effect was primarily driven by MA‐NC shape differences (SA vs MA‐NC Left: F 81,10 =16.71, p <0.001; Right: F 81,10 =3.26, p =0.001). Hippocampal shape did not differ between SA and O‐NC (Left: F 93,10 =0.95, p =0.5; Right: F 93,10 =1.10, p =0.41), but did significantly differ between O‐NC and MA‐NC in the left hemisphere ( F 42,10 =12.02, p <0.001), but not the right hemisphere ( F 42,10 =1.10, p =0.42). Conclusion Despite exceptional episodic memory performance, hippocampal integrity does not appear to be a strong discriminating factor in older adults with superior memory function. While no differences in global hippocampal volume between groups emerged, significant shape differences were noted in both SuperAgers and their age similar controls relative to middle‐aged controls. Overall, our findings may represent a phenomenon where memory ability in old age serves more as a function of a diffuse network of cortical structures rather than a single region. Future exploration would include evaluating connectivity of hippocampal‐involved networks that include regions such as medial temporal cortical and diencephalic structures.