Biomarker clusters are differentially associated with longitudinal cognitive decline in late midlife.
The ability to detect preclinical Alzheimer's disease is of great importance, as this stage of the Alzheimer's continuum is believed to provide a key window for intervention and prevention. As Alzheimer's disease is characterized by multiple pathological changes, a biomarker panel reflecting co-occurring pathology will likely be most useful for early detection. Towards this end, 175 late middle-aged participants (mean age 55.9 ± 5.7 years at first cognitive assessment, 70% female) were recruited from two longitudinally followed cohorts to undergo magnetic resonance imaging and lumbar puncture. Cluster analysis was used to group individuals based on biomarkers of amyloid pathology (cerebrospinal fluid amyloid-β42/amyloid-β40 assay levels), magnetic resonance imaging-derived measures of neurodegeneration/atrophy (cerebrospinal fluid-to-brain volume ratio, and hippocampal volume), neurofibrillary tangles (cerebrospinal fluid phosphorylated tau181 assay levels), and a brain-based marker of vascular risk (total white matter hyperintensity lesion volume). Four biomarker clusters emerged consistent with preclinical features of (i) Alzheimer's disease; (ii) mixed Alzheimer's disease and vascular aetiology; (iii) suspected non-Alzheimer's disease aetiology; and (iv) healthy ageing. Cognitive decline was then analysed between clusters using longitudinal assessments of episodic memory, semantic memory, executive function, and global cognitive function with linear mixed effects modelling. Cluster 1 exhibited a higher intercept and greater rates of decline on tests of episodic memory. Cluster 2 had a lower intercept on a test of semantic memory and both Cluster 2 and Cluster 3 had steeper rates of decline on a test of global cognition. Additional analyses on Cluster 3, which had the smallest hippocampal volume, suggest that its biomarker profile is more likely due to hippocampal vulnerability and not to detectable specific volume loss exceeding the rate of normal ageing. Our results demonstrate that pathology, as indicated by biomarkers, in a preclinical timeframe is related to patterns of longitudinal cognitive decline. Such biomarker patterns may be useful for identifying at-risk populations to recruit for clinical trials.
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 2 Institute on Aging, University of Wisconsin-Madison, USA, Madison, WI 53706, USA 3 Neuroscience and Public Policy Program, University of Wisconsin-Madison, USA, Madison, WI 53705, USA.
Annie M
AM
Racine
4 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA.
Rebecca L
RL
Koscik
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA.
Sara E
SE
Berman
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 5 Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, USA, Madison WI 53705, USA.
Christopher R
CR
Nicholas
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 4 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 5 Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, USA, Madison WI 53705, USA.
Lindsay R
LR
Clark
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 4 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA.
Ozioma C
OC
Okonkwo
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 6 Department of Radiology, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA.
Howard A
HA
Rowley
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 5 Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, USA, Madison WI 53705, USA.
Sanjay
S
Asthana
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 4 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA.
Barbara B
BB
Bendlin
7 Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden 8 Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.
Kaj
K
Blennow
7 Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden 8 Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden 9 Institute of Neurology, University College London, London, UK.
Henrik
H
Zetterberg
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 5 Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, USA, Madison WI 53705, USA.
Carey E
CE
Gleason
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 4 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 5 Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, USA, Madison WI 53705, USA.
Cynthia M
CM
Carlsson
1 Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 4 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, USA, Madison, WI 53705, USA 5 Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, USA, Madison WI 53705, USA 10 Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin-Madison, USA, Madison, WI 53705, USA scj@medicine.wisc.edu.
Sterling C
SC
Johnson
D000368:Aged; D000375:Aging / Q000134:cerebrospinal fluid / Q000473:pathology; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid / Q000000981:diagnostic imaging / Q000503:physiopathology; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D001284:Atrophy / Q000473:pathology; D015415:Biomarkers; D016000:Cluster Analysis; D060825:Cognitive Dysfunction / Q000134:cerebrospinal fluid / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging*; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000134:cerebrospinal fluid; D066127:White Matter / Q000000981:diagnostic imaging*
D016229:Amyloid beta-Peptides; D015415:Biomarkers; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)
cerebrospinal fluid; cluster analysis; longitudinal; neuroimaging; preclinical Alzheimer’s disease