title: Chronological age and its impact on associative learning proficiency and brain structure in middle adulthood.
abstract: BACKGROUND
  The rate of biological change in middle-adulthood is relatively under-studied. Here, we used behavioral testing in conjunction with structural magnetic resonance imaging to examine the effects of chronological age on associative learning proficiency and on brain regions that previous functional MRI studies have closely related to the domain of associative learning.
  
  
  METHODS
  Participants (n=66) completed a previously established associative learning paradigm, and consented to be scanned using structural magnetic resonance imaging. Age-related effects were investigated both across sub-groups in the sample (younger vs. older) and across the entire sample (using regression approaches).
  
  
  RESULTS
  Chronological age had substantial effects on learning proficiency (independent of IQ and Education Level), with older adults showing a decrement compared to younger adults. In addition, decreases in estimated gray matter volume were observed in multiple brain regions including the hippocampus and the dorsal prefrontal cortex, both of which are strongly implicated in associative learning.
  
  
  CONCLUSIONS
  The results suggest that middle adulthood may be a more dynamic period of life-span change than previously believed. The conjunctive application of narrowly focused tasks, with conjointly acquired structural MRI data may allow us to enrich the search for, and the interpretation of, age-related changes in cross-sectional samples.
authors.affiliation: Department of Psychiatry & Behavioral Neurosciences, Wayne State University, USA. Electronic address: vdiwadka@med.wayne.edu.
authors.forename: Vaibhav A
authors.initials: VA
authors.lastname: Diwadkar
authors.affiliation: InterUniversity Center for Behavioral Neurosciences, University of Verona, Italy; Department of Public Health & Community Medicine, University of Verona, Italy.
authors.forename: Marcella
authors.initials: M
authors.lastname: Bellani
authors.affiliation: Department of Psychiatry & Behavioral Neurosciences, Wayne State University, USA.
authors.forename: Rizwan
authors.initials: R
authors.lastname: Ahmed
authors.affiliation: InterUniversity Center for Behavioral Neurosciences, University of Verona, Italy; Department of Public Health & Community Medicine, University of Verona, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Dusi
authors.affiliation: InterUniversity Center for Behavioral Neurosciences, University of Verona, Italy; Department of Public Health & Community Medicine, University of Verona, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Rambaldelli
authors.affiliation: InterUniversity Center for Behavioral Neurosciences, University of Verona, Italy; Department of Public Health & Community Medicine, University of Verona, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Perlini
authors.affiliation: InterUniversity Center for Behavioral Neurosciences, University of Verona, Italy; Department of Public Health & Community Medicine, University of Verona, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Marinelli
authors.affiliation: Department of Psychiatry & Behavioral Neurosciences, Wayne State University, USA.
authors.forename: Karthik
authors.initials: K
authors.lastname: Ramaseshan
authors.affiliation: InterUniversity Center for Behavioral Neurosciences, University of Verona, Italy; Department of Public Health & Community Medicine, University of Verona, Italy.
authors.forename: Mirella
authors.initials: M
authors.lastname: Ruggeri
authors.affiliation: Department of Neurosciences and Mental Health, University of Milan, Milan, Italy; Scientific Institute IRCCS "E. Medea", Bosisio Parini (Lc), Italy. Electronic address: paolo.brambilla1@unimi.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Bambilla
mesh_terms: D000328:Adult; D000375:Aging / Q000473:pathology* / Q000523:psychology*; D001245:Association Learning; D001921:Brain / Q000473:pathology*; D005260:Female; D066128:Gray Matter / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D009929:Organ Size; D055815:Young Adult
keywords: Aging; Associative learning; Brain structure; Hippocampus; Life span changes; Voxel based morphometry