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Shen X, Raghavan S, Przybelski SA, Lesnick TG, Ma S, Reid RI, Graff-Radford J, Mielke MM, Knopman DS, Petersen RC, Jack CR, Simon GJ, Vemuri P. Causal structure discovery identifies risk factors and early brain markers related to evolution of white matter hyperintensities. Neuroimage Clin 2022; 35:103077. [PMID: 35696810 PMCID: PMC9194644 DOI: 10.1016/j.nicl.2022.103077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/25/2022] [Accepted: 06/03/2022] [Indexed: 11/25/2022]
Abstract
Our goal was to understand the complex relationship between age, sex, midlife risk factors, and early white matter changes measured by diffusion tensor imaging (DTI) and their role in the evolution of longitudinal white matter hyperintensities (WMH). We identified 1564 participants (1396 cognitively unimpaired, 151 mild cognitive impairment and 17 dementia participants) with age ranges of 30-90 years from the population-based sample of Mayo Clinic Study of Aging. We used computational causal structure discovery and regression analyses to evaluate the predictors of WMH and DTI, and to ascertain the mediating effect of DTI on WMH. We further derived causal graphs to understand the complex interrelationships between midlife protective factors, vascular risk factors, diffusion changes, and WMH. Older age, female sex, and hypertension were associated with higher baseline and progression of WMH as well as DTI measures (P ≤ 0.003). The effects of hypertension and sex on WMH were partially mediated by microstructural changes measured on DTI. Higher midlife physical activity was predictive of lower WMH through a direct impact on better white matter tract integrity as well as an indirect effect through reducing the risk of hypertension by lowering BMI. This study identified key risks factors, early brain changes, and pathways that may lead to the evolution of WMH.
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Affiliation(s)
- Xinpeng Shen
- Institute for Health Informatics, University of Minnesota, Minneapolis, MN, USA; Departments of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | | | | | - Sisi Ma
- Institute for Health Informatics, University of Minnesota, Minneapolis, MN, USA
| | - Robert I Reid
- Information Technology, Mayo Clinic, Rochester, MN, USA
| | | | - Michelle M Mielke
- Quantitative Health Sciences, Mayo Clinic, Rochester, MN, USA; Departments of Neurology, Mayo Clinic, Rochester, MN, USA
| | | | | | | | - György J Simon
- Institute for Health Informatics, University of Minnesota, Minneapolis, MN, USA
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Associations of cigarette smoking with gray and white matter in the UK Biobank. Neuropsychopharmacology 2020; 45:1215-1222. [PMID: 32032968 PMCID: PMC7235023 DOI: 10.1038/s41386-020-0630-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 01/27/2020] [Accepted: 01/30/2020] [Indexed: 11/14/2022]
Abstract
Cigarette smoking is associated with increased risk for myriad health consequences including cognitive decline and dementia, but research on the link between smoking and brain structure is nascent. In the current study, we assessed the relationship of cigarette smoking with gray matter (GM) and white matter (WM) in the UK Biobank, controlling for numerous confounding demographic and health variables. We used negative-binomial regression to model the association of cigarette smoking (having ever smoked regularly, cigarettes per day, and duration smoked) with GM and WM (GM N = 19,615; WM N = 17,760), adjusting for confounders. Ever smoked and duration were associated with smaller total GM volume. Ever smoked was associated with reduced volume of the right VIIIa cerebellum and elevated WM hyperintensity volume. Smoking duration was associated with reduced total WM volume. Regarding specific tracts, ever smoked was associated with reduced fractional anisotropy in the left cingulate gyrus part of the cingulum, left posterior thalamic radiation, and bilateral superior thalamic radiation, and increased mean diffusivity in the middle cerebellar peduncle, right medial lemniscus, bilateral posterior thalamic radiation, and bilateral superior thalamic radiation. This study identified significant associations of cigarette exposure with global measures of GM and WM, and select associations of ever smoked, but not cigarettes per day or duration, with specific GM and WM regions. By controlling for important sociodemographic and health confounders, such as alcohol use, this study identifies distinct associations between smoking and brain structure, highlighting potential mechanisms of risk for common neurological sequelae (e.g., dementia).
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Mukherjee J, Lao PJ, Betthauser TJ, Samra GK, Pan ML, Patel IH, Liang C, Metherate R, Christian BT. Human brain imaging of nicotinic acetylcholine α4β2* receptors using [ 18 F]Nifene: Selectivity, functional activity, toxicity, aging effects, gender effects, and extrathalamic pathways. J Comp Neurol 2017; 526:80-95. [PMID: 28875553 DOI: 10.1002/cne.24320] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/22/2017] [Accepted: 08/23/2017] [Indexed: 02/06/2023]
Abstract
Nicotinic acetylcholinergic receptors (nAChR's) have been implicated in several brain disorders, including addiction, Parkinson's disease, Alzheimer's disease and schizophrenia. Here we report in vitro selectivity and functional properties, toxicity in rats, in vivo evaluation in humans, and comparison across species of [18 F]Nifene, a fast acting PET imaging agent for α4β2* nAChRs. Nifene had subnanomolar affinities for hα2β2 (0.34 nM), hα3β2 (0.80 nM) and hα4β2 (0.83 nM) nAChR but weaker (27-219 nM) for hβ4 nAChR subtypes and 169 nM for hα7 nAChR. In functional assays, Nifene (100 μM) exhibited 14% agonist and >50% antagonist characteristics. In 14-day acute toxicity in rats, the maximum tolerated dose (MTD) and the no observed adverse effect level (NOAEL) were estimated to exceed 40 μg/kg/day (278 μg/m2 /day). In human PET studies, [18 F]Nifene (185 MBq; <0.10 μg) was well tolerated with no adverse effects. Distribution volume ratios (DVR) of [18 F]Nifene in white matter thalamic radiations were ∼1.6 (anterior) and ∼1.5 (superior longitudinal fasciculus). Habenula known to contain α3β2 nAChR exhibited low levels of [18 F]Nifene binding while the red nucleus with α2β2 nAChR had DVR ∼1.6-1.7. Females had higher [18 F]Nifene binding in all brain regions, with thalamus showing >15% than males. No significant aging effect was observed in [18 F]Nifene binding over 5 decades. In all species (mice, rats, monkeys, and humans) thalamus showed highest [18 F]Nifene binding with reference region ratios >2 compared to extrathalamic regions. Our findings suggest that [18 F]Nifene PET may be used to study α4β2* nAChRs in various CNS disorders and for translational research.
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Affiliation(s)
- Jogeshwar Mukherjee
- Preclinical Imaging, Department of Radiological Sciences, University of California, Irvine, California
| | - Patrick J Lao
- Department of Medical Physics and Waisman Center, University of Wisconsin, Madison, Wisconsin
| | - Tobey J Betthauser
- Department of Medical Physics and Waisman Center, University of Wisconsin, Madison, Wisconsin
| | - Gurleen K Samra
- Preclinical Imaging, Department of Radiological Sciences, University of California, Irvine, California
| | - Min-Liang Pan
- Preclinical Imaging, Department of Radiological Sciences, University of California, Irvine, California
| | - Ishani H Patel
- Preclinical Imaging, Department of Radiological Sciences, University of California, Irvine, California
| | | | - Raju Metherate
- Department of Neurobiology and Behavior, University of California, Irvine, California
| | - Bradley T Christian
- Department of Medical Physics and Waisman Center, University of Wisconsin, Madison, Wisconsin
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