Both AD and dyslipidemias are global public health problems

Both AD and dyslipidemias are global public health problems, and an increase in their incidence over the next decades is expected. Among many triggering elements, the increase in life expectancy is one of the main risk factors associated with the increase in the incidence of AD. Meanwhile, dyslipidemias have several triggering factors, such as genetic background and diet patterns. AD prognosis can be worsened when the disease in associated with dyslipidemias and inflammation, being this last one initiated by both pathological conditions. Although little is known about the molecular mechanisms of this association, increased inflammatory response, release of cytokines, and cholesterol and LDL levels are features of AD (albeit many mechanisms have been proposed and reported in this review; Fig. 1). Therefore, more studies are needed to clarify the molecular mechanisms underlying the association between dyslipidemia and inflammation during AD. A deeper understanding of these mechanisms might enable the development of new therapeutic approaches.
Acknowledgments We thank Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) – Brazil and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) – Brazil for the financial support. ACPdO and HJR acknowledge CNPq for the Research Productivity Fellowships. We thank Dr. Magda da Silva Santos, from the Department of Psychiatry, University of California San Francisco, for revising the manuscript.
Alzheimer’s disease (AD) is a progressive and irreversible induced pluripotent stem cell disorder that is characterized by a gradual degradation of cognitive functions over many years that includes a long preclinical phase . Because brain atrophy as measured with magnetic resonance imaging (MRI) correlates with neuron loss , longitudinal in vivo neuroimaging has become invaluable for studying trajectories of pathophysiological change in AD. Repeated volumetric measurements of brain volumes in the same individuals have shown accelerated rates of atrophy in patients with AD compared with healthy control subjects, even in preclinical stages . Volume measurements are, however, only a crude simplification of the complex anatomical change that occurs in aging and AD and often ignore the fact that atrophy is not uniform across a brain structure, e.g., the hippocampus , , . In contrast, shape descriptors are sensitive to such changes as they retain more geometrical information . Indeed, a recent study revealed that subtle preclinical changes in the shape asymmetry of subcortical brain structures could predict the conversion from mild cognitive impairment (MCI) to dementia more accurately than volumetric asymmetry . These asymmetries are undirectional, i.e., they do not have a consistent hemispheric effect and therefore refer to the magnitude of asymmetry independent of direction. While structural asymmetries could serve as imaging biomarkers for the early presymptomatic classification and prediction of AD, possible biological mechanisms that underlie asymmetric manifestation of AD pathology are unclear. Here, we investigate the genetic influence on shape asymmetry in AD in an imaging quantitative trait loci (QTL) analysis including healthy control subjects and MCI stable, MCI progressor, and AD patients. While previous genome-wide association studies (GWASs) have revealed single nucleotide polymorphisms (SNPs) that are related to AD diagnosis, the mechanism through which they affect the disease remains largely unknown. Relating these same SNPs to imaging markers helps our understanding of how common genetic variants alter specific structures and pathways in the living human brain . Because previous research is inconsistent with respect to heritability of brain structural asymmetry , , , we model both main effects of SNP as well as interactions between diagnosis groups and SNP on brain asymmetry. Whereas main effects speak to heritability per se, a significant interaction would reveal genetic influences on brain shape asymmetry that are magnified in AD patients and therefore can be interpreted to reflect the development of disease .