Genetic Analysis of Association Between Calcium Signaling and Hippocampal Activation, Memory Performance in the Young and Old, and Risk for Sporadic Alzheimer Disease.
OBJECTIVE
Human episodic memory performance is linked to the function of specific brain regions, including the hippocampus; declines as a result of increasing age; and is markedly disturbed in Alzheimer disease (AD), an age-associated neurodegenerative disorder that primarily affects the hippocampus. Exploring the molecular underpinnings of human episodic memory is key to the understanding of hippocampus-dependent cognitive physiology and pathophysiology.


OBJECTIVE
To determine whether biologically defined groups of genes are enriched in episodic memory performance across age, memory encoding-related brain activity, and AD.


METHODS
In this multicenter collaborative study, which began in August 2008 and is ongoing, gene set enrichment analysis was done by using primary and meta-analysis data from 57 968 participants. The Swiss cohorts consisted of 3043 healthy young adults assessed for episodic memory performance. In a subgroup (n = 1119) of one of these cohorts, functional magnetic resonance imaging was used to identify gene set-dependent differences in brain activity related to episodic memory. The German Study on Aging, Cognition, and Dementia in Primary Care Patients cohort consisted of 763 elderly participants without dementia who were assessed for episodic memory performance. The International Genomics of Alzheimer's Project case-control sample consisted of 54 162 participants (17 008 patients with sporadic AD and 37 154 control participants). Analyses were conducted between January 2014 and June 2015. Gene set enrichment analysis in all samples was done using genome-wide single-nucleotide polymorphism data.


METHODS
Episodic memory performance in the Swiss cohort and German Study on Aging, Cognition, and Dementia in Primary Care Patients cohort was quantified by picture and verbal delayed free recall tasks. In the functional magnetic resonance imaging experiment, activation of the hippocampus during encoding of pictures served as the phenotype of interest. In the International Genomics of Alzheimer's Project sample, diagnosis of sporadic AD served as the phenotype of interest.


RESULTS
In the discovery sample, we detected significant enrichment for genes constituting the calcium signaling pathway, especially those related to the elevation of cytosolic calcium (P = 2 × 10-4). This enrichment was replicated in 2 additional samples of healthy young individuals (P = .02 and .04, respectively) and a sample of healthy elderly participants (P = .004). Hippocampal activation (P = 4 × 10-4) and the risk for sporadic AD (P = .01) were also significantly enriched for genes related to the elevation of cytosolic calcium.


CONCLUSIONS
By detecting consistent significant enrichment in independent cohorts of young and elderly participants, this study identified that calcium signaling plays a central role in hippocampus-dependent human memory processes in cognitive health and disease, contributing to the understanding and potential treatment of hippocampus-dependent cognitive pathology.
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland2Psychiatric University Clinic, University of Basel, Basel, Switzerland.
Angela
A
Heck
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland3Division of Cognitive Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland.
Matthias
M
Fastenrath
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland3Division of Cognitive Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland.
David
D
Coynel
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland.
Bianca
B
Auschra
Department of Psychiatry, Technical University of Munich, Munich, Germany.
Horst
H
Bickel
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland.
Virginie
V
Freytag
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland3Division of Cognitive Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland.
Leo
L
Gschwind
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland.
Francina
F
Hartmann
Department of Psychiatry, University of Cologne, Medical Faculty, Cologne, Germany6German Center for Neurodegenerative Diseases, Bonn, Germany.
Frank
F
Jessen
Institute of General Practice, Kiel University, Kiel, Germany.
Hanna
H
Kaduszkiewicz
German Center for Neurodegenerative Diseases, Bonn, Germany8Department of Psychiatry, University of Bonn, Bonn, Germany.
Wolfgang
W
Maier
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland2Psychiatric University Clinic, University of Basel, Basel, Switzerland.
Annette
A
Milnik
Department of General Practice, University Medical Center Düsseldorf, Düsseldorf, Germany.
Michael
M
Pentzek
Institute of Social Medicine, Occupational Health, and Public Health, University of Leipzig, Leipzig, Germany.
Steffi G
SG
Riedel-Heller
Division of Cognitive Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland.
Klara
K
Spalek
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland2Psychiatric University Clinic, University of Basel, Basel, Switzerland.
Christian
C
Vogler
German Center for Neurodegenerative Diseases, Bonn, Germany8Department of Psychiatry, University of Bonn, Bonn, Germany.
Michael
M
Wagner
Central Institute of Mental Health, Mannheim/Heidelberg University, Mannheim, Germany.
Siegfried
S
Weyerer
German Center for Neurodegenerative Diseases, Bonn, Germany8Department of Psychiatry, University of Bonn, Bonn, Germany.
Steffen
S
Wolfsgruber
Psychiatric University Clinic, University of Basel, Basel, Switzerland3Division of Cognitive Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland.
Dominique J-F
DJ
de Quervain
Division of Molecular Neuroscience, Department of Psychology, University of Basel, Basel, Switzerland2Psychiatric University Clinic, University of Basel, Basel, Switzerland12Life Sciences Training Facility, Department Biozentrum, University of Basel, Base.
Andreas
A
Papassotiropoulos
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000235:genetics* / Q000503:physiopathology; D020013:Calcium Signaling / Q000235:genetics*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D059907:Functional Neuroimaging; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D061212:Memory, Episodic; D008875:Middle Aged; D011446:Prospective Studies; D055815:Young Adult