Peripheral Leukocytosis Predicts Cognitive Decline but Not Behavioral Disturbances: A Nationwide Study of Alzheimer's and Parkinson's Disease Patients

Role of inflammation in the socioeconomic inequalities of neurocognitive disorders

BACKGROUND

Socioeconomic position has been shown to be associated with inflammation. However, little is known about the role of inflammation in socioeconomic inequalities in relation to neurocognitive disorders in later life and the potential underlying inflammatory mechanisms. This study has used longitudinal data to investigate the mediation effects of inflammation in the relationship between socioeconomic position and neurocognitive disorders in older adults.

METHODS

Using data from the English Longitudinal Study of Ageing (ELSA, n = 4,815), we ascertained neurocognitive disorders using a recognised consensus criterion and included the following categories: (1) No Cognitive Impairment (NOCI) (2) Cognitive Impairment No Dementia (CIND) and (3) Dementia. We examined whether socioeconomic position (education, occupation, and wealth) measured in 2008/09 was associated with neurocognitive disorders measured in 2018/19. Mediation analyses were carried out to investigate the role of inflammatory markers [C-Reactive Protein (CRP), plasma fibrinogen and white blood cells (WBC)] in the association between socioeconomic inequalities and subsequent neurocognitive disorders. Sensitivity analyses were conducted to assess the mediating role of lifestyle behaviours and body mass index (BMI).

RESULTS

Higher education, occupation and wealth were longitudinally associated with a lower likelihood of cognitive impairment and dementia. WBC mediated the association between latent socioeconomic position and CIND [β = -0.037 (CI: -0.06 to -0.01)], but not the association with dementia. Indirect effects were attenuated but remained significant when other mediators, such as lifestyle behaviours and BMI were considered. In a separate analysis accounting for main confounders, CRP and fibrinogen mediated the association between education and CIND, all three inflammatory biomarkers mediated the association of occupation and CIND, while WBC mediated the association between wealth and CIND.

CONCLUSION

These findings emphasise that socioeconomic inequalities in mid and later life could contribute to the prevalence of neurocognitive disorders in later life. Our results provide some evidence for the biological embedding of WBC in the association between socioeconomic inequalities and cognitive impairment via elevated inflammation. Future studies should explore other plausible biological mechanisms.

Cysteine Donor-Based Brain-Targeting Prodrug: Opportunities and Challenges

Overcoming blood-brain barrier (BBB) to improve brain bioavailability of therapeutic drug remains an ongoing concern. Prodrug is one of the most reliable approaches for delivering agents with low-level BBB permeability into the brain. The well-known antioxidant capacities of cysteine (Cys) and its vital role in glutathione (GSH) synthesis indicate that Cys-based prodrug could potentiate therapeutic drugs against oxidative stress-related neurodegenerative disorders. Moreover, prodrug with Cys moiety could be recognized by the excitatory amino acid transporter 3 (EAAT3) that is highly expressed at the BBB and transports drug into the brain. In this review, we summarized the strategies of crossing BBB, properties of EAAT3 and its natural substrates, Cys and its donors, and Cys donor-based brain-targeting prodrugs by referring to recent investigations. Moreover, the challenges that we are faced with and future research orientations were also addressed and proposed. It is hoped that present review will provide evidence for the pursuit of novel Cys donor-based brain-targeting prodrug.

Novel Insights into the Role of Probiotics in Respiratory Infections, Allergies, Cancer, and Neurological Abnormalities

In recent years, probiotics have attracted public attention and transformed the social perception of microorganisms, convening a beneficial role/state on human health. With aging, the immune system, body physiology, and intestinal microbiota tend to change unfavorably, resulting in many chronic conditions. The immune-mediated disorders can be linked to intestinal dysbiosis, consequently leading to immune dysfunctions and a cluster of conditions such as asthma, autoimmune diseases, eczema, and various allergies. Probiotic bacteria such as Lactobacillus and Bifidobacterium species are considered probiotic species that have a great immunomodulatory and anti-allergic effect. Moreover, recent scientific and clinical data illustrate that probiotics can regulate the immune system, exert anti-viral and anti-tumoral activity, and shields the host against oxidative stress. Additionally, microbiota programming by probiotic bacteria can reduce and prevent the symptoms of respiratory infections and ameliorate the neurological status in humans. This review describes the most recent clinical findings, including safe probiotic therapies aiming to medicate respiratory infections, allergies, cancer, and neurological disorders due to their physiological interconnection. Subsequently, we will describe the major biological mechanism by which probiotic bacteriotherapy expresses its anti-viral, anti-allergic, anticancer, and neuro-stimulatory effects.