The relationship of weight change trajectory with medial temporal lobe atrophy in patients with mild Alzheimer's disease: results from a cohort study

Weight Loss Is a Strong Predictor of Memory Disorder Independent of Genetic Influences

BACKGROUND

Past studies identified a link between weight loss and dementia, but lacked consistent conclusions. We sought to establish this link by examining the weight change profiles before and after dementia diagnosis.

METHODS

Using data from the Health and Retirement Study (1996-2020), we examined 13,123 participants. We conducted a nested case-control analysis to assess differences in biennial weight change profile while controlling for BMI, longevity polygenic risk scores, and APOE gene variants.

RESULTS

Participants with a memory disorder lost weight (-0.63%) biennially, whereas those without a diagnosis did not (+0.013%, p-value < 0.0001). Our case-control study shows a significant difference (p-value < 0.01) in pre-dementia % weight changes between the cases (-0.29%) and controls (0.19%), but not in post-dementia weight changes. The weight loss group have the highest risk (OR = 2.01; p-value < 0.0001) of developing a memory disorder compared to the stable weight and weight gain groups. The observations hold true after adjusting for BMI, longevity polygenic risk scores, and APOE variant in a multivariable model.

CONCLUSIONS

We observe that weight loss in dementia is a physiological process independent of genetic factors associated with BMI and longevity. Pre-dementia weight loss may be an important prognostic criterion to assess a person's risk of developing a memory disorder.

Sex differences in dementia with Lewy bodies: an imaging study of neurotransmission pathways

PURPOSE

Dementia with Lewy bodies (DLB) is characterized by a wide clinical and biological heterogeneity, with sex differences reported in both clinical and pathologically confirmed DLB cohorts. No research evidence is available on sex differences regarding molecular neurotransmission. This study aimed to assess whether sex can influence neurotransmitter systems in patients with probable DLB (pDLB).

METHODS

We included 123 pDLB patients (male/female: 77/46) and 78 control subjects (male/female: 34/44) for comparison, who underwent 123I-FP-CIT SPECT imaging. We assessed sex differences in the dopaminergic activity of the nigrostriatal and mesolimbic systems using regional-based and voxel-wise analyses of 123I-FP-CIT binding. We tested whether sex-specific binding alterations would also pertain to the serotoninergic and noradrenergic systems by applying spatial correlation analyses. We applied molecular connectivity analyses to assess potential sex differences in the dopaminergic pathways.

RESULTS

We found comparable 123I-FP-CIT binding decreases in the striatum for pDLB males and females compared to controls. However, pDLB females showed lower binding in the extrastriatal projections of the nigrostriatal and mesolimbic dopaminergic systems compared to pDLB males. According to the spatial correlation analysis, sex-specific molecular alterations were also associated with serotonergic and noradrenergic systems. Nigrostriatal and mesolimbic systems' connectivity was impaired in both groups, with males showing local alterations and females presenting long-distance disconnections between subcortical and cortical regions.

CONCLUSIONS

Sex-specific differences in 123I-FP-CIT binding were found in our cohort, namely, a trend for lower 123I-FP-CIT binding in females, significant in the presence of a pDLB diagnosis. pDLB females showed also different patterns of connectivity compared to males, mostly involving extrastriatal regions. The results suggest the presence of a sex-related regional vulnerability to alpha-synuclein pathology, possibly complicated also by the higher prevalence of Alzheimer's disease co-pathology in females, as previously reported in pDLB populations.

Crosstalk between obesity, diabetes, and alzheimer's disease: Introducing quercetin as an effective triple herbal medicine

Obesity and diabetes are the most common metabolic disorders, which are strongly related to Alzheimer's disease (AD) in aging. Diabetes and obesity can lead to the accumulation of amyloid plaques, neurofibrillary tangles (NFTs), and other symptoms of AD through several pathways, including insulin resistance, hyperglycemia, hyperinsulinemia, chronic inflammation, oxidative stress, adipokines dysregulation, and vascular impairment. Currently, the use of polyphenols has been expanded in animal models and in-vitro studies because of their comparatively negligible adverse effects. Among them, quercetin (QT) is one of the most abundant polyphenolic flavonoids, which is present in fruits and vegetables and displays many biological, health-promoting effects in a wide range of diseases. The low bioavailability and poor solubility of QT have also led researchers to make various QT-involved nanoparticles (NPs) to overcome these limitations. In this paper, we review significant molecular mechanisms induced by diabetes and obesity that increase AD pathogenesis. Then, we summarize in vitro, in vivo, and clinical evidence regarding the anti-Alzheimer, anti-diabetic and anti-obesity effects of QT. Finally, QT in pure and combination form using NPs has been suggested as a promising therapeutic agent for future studies.

Lifestyle intervention to prevent Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disease that leads to significant morbidities in elderly. The major pathological hallmark of AD is beta-amyloid plaques (Aβ) and intracellular neurofibrillary tangles (NFTs) deposition in hippocampus of the brain. These abnormal protein deposition damages neuronal cells resulting in neurodegeneration and cognitive decline. As a result of limited treatment options available for this disease, there is huge economic burden for patients and social health care system. Thus, alternative approaches (lifestyle intervention) to prevent this disease are extremely important. In this systemic review, we summarized epidemiological evidence of lifestyle intervention and the mechanisms involved in delaying and/or preventing AD. Lifestyle interventions include education, social engagement and cognitive stimulation, smoking, exercise, depression and psychological stress, cerebrovascular disease (CVD), hypertension (HTN), dyslipidaemia, diabetes mellitus (DM), obesity and diet. The methods are based on a literature review of available sources found on the research topic in four acknowledged databases: Web of Science, Scopus, Medline and PubMed. Results of the identified original studies revealed that lifestyle interventions have significant effects and our conclusion is that combination of early lifestyle interventions can decrease the risk of developing AD.

The Role of Irisin in Alzheimer's Disease

Alzheimer’s disease (AD) is characterized by progressive memory dysfunction, oxidative stress, and presence of senile plaques formed by amyloid beta (Aβ) accumulation in the brain. AD is one of the most important causes of morbidity and mortality worldwide. AD has a variety of risk factors, including environmental factors, metabolic dysfunction, and genetic background. Recent research has highlighted the relationship between AD and systemic metabolic changes such as glucose and lipid imbalance and insulin resistance. Irisin, a myokine closely linked to exercise, has been associated with glucose metabolism, insulin sensitivity, and fat browning. Recent studies have suggested that irisin is involved in the process in central nervous system (CNS) such as neurogenesis and has reported the effects of irisin on AD as one of the neurodegenerative disease. Here, we review the roles of irisin with respect to AD and suggest that irisin highlight therapeutic important roles in AD. Thus, we propose that irisin could be a potential future target for ameliorating AD pathology and preventing AD onset.

Subcortical nuclei in Alzheimer's disease: a volumetric and diffusion kurtosis imaging study

Background Previous studies revealed that subcortical nuclei were harmed in the process of Alzheimer's disease (AD). Purpose To investigate the volumetric and diffusion kurtosis imaging (DKI) parameter changes of subcortical nuclei in AD and their relationship with cognitive function. Materials and Methods A total of 17 mild AD patients, 15 moderate to severe AD patients, and 16 controls underwent neuropsychological tests and magnetic resonance imaging (MRI) scans. Volume, mean kurtosis (MK), mean diffusivity (MD), and fractional anisotropy (FA) were measured in hippocampus, thalamus, caudate, putamen, pallidum, and amygdala. MRI parameters were compared. Correlation analysis was performed between subcortical nuclei volume, DKI parameters, and MMSE score. Results Significant volume reduction was seen in the left hippocampus in mild AD, and the bilateral hippocampus, thalamus, putamen, left caudate, and right amygdala in moderate to severe AD ( P < 0.05). Increased MD values were observed in the left hippocampus, left amygdala, and right caudate in mild AD, and the bilateral hippocampus and right amygdala in moderate to severe AD ( P < 0.05). Decreased MK values were observed only in the bilateral hippocampus in moderate to severe AD ( P < 0.05). No group significances were found in FA value. MMSE score was positively correlated with the volume of the bilateral hippocampus, thalamus, and putamen, and MK value of the left hippocampus ( P < 0.05). A negative correlation was found with the MD value of the bilateral hippocampus and left amygdala ( P < 0.05). Conclusion Mild AD mainly has microscopic subcortical changes revealed by increased MD value, and moderate to severe AD mainly has macroscopic subcortical changes revealed by volume reduction. MK is more sensitive in severe AD than mild AD.

Obesity as a risk factor for Alzheimer's disease: weighing the evidence

Alzheimer's disease (AD) is the sixth leading cause of death in the USA today; therefore, it is imperative that public health initiatives and clinical strategies are developed to prevent and effectively treat AD. Despite the enormous impact that AD has on individuals, families, society, and the health care system, there are no biomarkers to clearly identify those at risk for AD, public health prevention strategies in place, or treatments to address the underlying pathology or stop the progression of AD. There is ample scientific as well as empirical evidence that obesity and its metabolic and vascular comorbidities are related to AD and likely in the causative pathway. Obesity prevention and treatment could prove to be an efficacious and safe approach to preventing AD, a serious and daunting epidemic disease. In this review, we present the current pathophysiological and clinical evidence linking obesity and obesity-related comorbidities (eg, insulin resistance, hyperglycaemia, and type 2 diabetes) with AD. Additionally, we discuss which population to target and when to consider treatment for AD. Finally, we summarize the current evidence regarding the efficacy of anti-obesity and anti-diabetic pharmacotherapeutic agents for the treatment of AD.