Beyond the Obvious: Smoking and Respiratory Infection Implications on Alzheimer's Disease

Abstract

Background: Tobacco smoke is not only a leading cause for chronic obstructive pulmonary disease, cardiovascular disorders, lung and oral cancers but also causes neurological disorders such as Alzheimer's disease. Tobacco smoke consists of more than 4500 toxic chemicals, which form free radicals and can cross blood brain barrier resulting in oxidative stress, an extracellular amyloid plaque from the aggregation of amyloid β (Aβ) peptide deposition in the brain. Further, respiratory infections such as Chlamydia pneumoniae, respiratory syncytial virus have also been involved in the induction and development of the disease. Methods: The necessary information collated on this review has been gathered from various literature published from 1995 to 2019. Findings: The review article sheds light on the role of smoking and respiratory infections in causing oxidative stress and neuroinflammation resulting in Alzheimer's disease (AD). This review will be of interest to scientists and researchers from biological and medical science disciplines including microbiology, pharmaceutical sciences and the translational researchers, etc. Conclusion: The increasing understanding of the relationship between chronic lung disease and neurological disease are two-fold. First, this would help to identify the risk factors and possible therapeutic interventions to reduce the development and progression of both diseases. Second, this would help to reduce the probable risk of development of AD in the population prone to chronic lung diseases.

Association of Chronic Obstructive Pulmonary Disease with Risk of Psychiatric Disorders: A Two-Sample Mendelian Randomization Study

“… 38 Smoking may emerge as a pivotal modifiable risk factor in the pathogenesis of Alzheimer’s disease. 39 Among older adults, successful quitters exhibited a significantly slower rate of cognitive decline than those who continued smoking during the subsequent 2-year period. 40 Based on the above findings, it can be inferred that quitting smoking following COPD diagnosis may confer a protective effect against the development of Alzheimer’s disease in previous smokers.…”

Immunopathology of herpes simplex virus‐associated neuroinflammation: Unveiling the mysteries

“…66 In the realm of innate immune responses to DNA, including that from HSV-1, the involvement of the transcription factor IRF8 within monocytes is crucial. [66][67][68] Nevertheless, HSV-1 has developed tactics to elude the innate immune response. It accomplishes this by neutralising host antiviral factors and targeting various cellular DNA sensor-mediated signalling pathway stages.…”

“…Essential for resisting mucosal HSV‐1 infection via an intravaginal route is the simultaneous recognition of TLR2/9, demonstrating the significance of this dual recognition 66 . In the realm of innate immune responses to DNA, including that from HSV‐1, the involvement of the transcription factor IRF8 within monocytes is crucial 66–68 …”

The Cause of Alzheimer’s Disease: The Theory of Multipathology Convergence to Chronic Neuronal Stress

“…Furthermore, cadmium was found to be elevated in the blood of Korean women exposed to secondhand smoke during their daily activities [ 185 ], implying that passive exposure to tobacco smoke is sufficient to increase blood levels of some toxic metal ions. The toxic effects of tobacco product usage stimulates hypoxia, liver detoxification processes, oxidative stress, and vascular damage [ 186 ], all of which can induce chronic neuronal stress in the CNS and perhaps increase the risk of developing AD [ 187 ]. Very importantly, epidemiological studies have linked the concomitant heavy consumption of alcohol and smoking with an increased risk of developing chronic liver diseases [ 188 ].…”