Dengue and dementia risk: A nationwide longitudinal study

Dengue versus COVID-19: comparing the incidence of cardiovascular, neuropsychiatric and autoimmune complications

BACKGROUND

While persistence of chronic symptoms following dengue infection has been documented in small prospective cohorts, population-based studies are limited. The post-acute risk of new-incident multi-systemic complications following dengue infection was contrasted against that following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in a multi-ethnic adult Asian population.

METHODS

National testing and healthcare claims that databases in Singapore were utilized to build a retrospective population-based adult cohort with laboratory-confirmed infection during overlapping waves of SARS-CoV-2 and dengue transmission (1 July 2021 to 31 October 2022). Risks of new-incident cardiovascular/neuropsychiatric/autoimmune complications 31-300 days of post-dengue infection, contrasted with SARS-CoV-2 infection, were estimated using Cox regression with overlap weights. Risks were reported in terms of adjusted hazard ratio (aHR) and excess burden per 1000 persons.

RESULTS

11 707 dengue-infected individuals and 1 248 326 contemporaneous coronavirus disease 2019 (COVID-19) cases were included; the majority had mild initial infection not requiring hospitalization. Amongst dengue-infected individuals, there was 21% [aHR = 1.21 (1.06-1.38)] increased risk of any sequelae, with 55% [aHR = 1.55 (1.27-1.89)] increased risk of cardiovascular sequelae. Specifically, increased risk of dysrhythmias [aHR = 1.79(1.35-2.37)], ischemic heart disease [aHR = 1.45(1.12-1.89)], other cardiac disorders [aHR = 2.21(1.54-3.16)] and thrombotic disorders [aHR = 2.55(1.50-4.35)] was noted. Elevated risk of individual neuropsychiatric sequelae, including cerebrovascular disorders [aHR = 1.49(1.09-2.13)], cognition/memory disorders [aHR = 2.13(1.55-2.93)], extrapyramidal/movement disorders [aHR = 1.98(1.33-2.94)] and anxiety disorders [aHR = 1.61(1.01-2.56)], was observed in dengue-infected individuals compared to COVID-19 cases. Elevated risks of post-acute sequelae in dengue survivors were observed when contrasted against COVID-19 survivors infected during Delta/Omicron predominance, as well as across vaccination strata.

CONCLUSION

Increased risk of post-acute cardiovascular/neuropsychiatric complications was observed in dengue survivors, when contrasted against COVID-19 survivors infected during Delta/Omicron predominance.

RESEARCH IN CONTEXT

Re-examination of the risk of dementia after dengue virus infection: A population-based cohort study

Dengue infection can affect the central nervous system and cause various neurological complications. Previous studies also suggest dengue was associated with a significantly increased long-term risk of dementia. A population-based cohort study was conducted using national health databases in Taiwan and included 37,928 laboratory-confirmed dengue patients aged ≥ 45 years between 2002 and 2015, along with 151,712 matched nondengue individuals. Subdistribution hazard regression models showed a slightly increased risk of Alzheimer's disease, and unspecified dementia, non-vascular dementia, and overall dementia in dengue patients than the nondengue group, adjusted for age, sex, area of residence, urbanization level, income, comorbidities, and all-cause clinical visits within one year before the index date. After considering multiple comparisons using Bonferroni correction, only overall dementia and non-vascular dementia remained statistically significant (adjusted SHR 1.13, 95% CI 1.05-1.21, p = 0.0009; E-value 1.51, 95% CI 1.28-NA). Sensitivity analyses in which dementia cases occurring in the first three or five years after the index dates were excluded revealed no association between dengue and dementia. In conclusion, this study found dengue patients had a slightly increased risk of non-vascular dementia and total dementia than those without dengue. However, the small corresponding E-values and sensitivity analyses suggest the association between dengue and dementia may not be causal.

Cognitive dysfunction in post-COVID-19 condition: Mechanisms, management, and rehabilitation

The long-term effects of COVID-19 on cognitive function have become an area of increasing concern. This paper provides an overview of characteristics, risk factors, possible mechanisms, and management strategies for cognitive dysfunction in post-COVID-19 condition (PCC). Prolonged cognitive dysfunction is one of the most common impairments in PCC, affecting between 17% and 28% of the individuals more than 12 weeks after the infection and persisting in some cases for several years. Cognitive dysfunctions can be manifested as a wide range of symptoms including memory impairment, attention deficit, executive dysfunction, and reduced processing speed. Risk factors for developing PCC, with or without cognitive impairments, include advanced age, preexisting medical conditions, and the severity of acute illness. The underlying mechanisms remain unclear, but proposed contributors include neuroinflammation, hypoxia, vascular damage, and latent virus reactivation not excluding the possibility of direct viral invasion of the central nervous system, illustrating complex viral pathology. As the individual variation of the cognitive impairments is large, a neuropsychological examination and a person-centered multidimensional approach are required. According to the World Health Organization, limited evidence on COVID-19-related cognitive impairments necessitates implementing rehabilitation interventions from established practices of similar conditions. Psychoeducation and compensatory skills training are recommended. Assistive products and environmental modifications adapted to individual needs might be helpful. In specific attention- and working memory dysfunctions, cognitive training-carefully monitored for intensity-might be effective for people who do not suffer from post-exertional malaise. Further research is crucial for evidence-based interventions specific to COVID-19-related cognitive impairments.

Alzheimer's disease as a viral disease: Revisiting the infectious hypothesis

Alzheimer's disease (AD) represents the most frequent type of dementia in elderly people. Two major forms of the disease exist: sporadic - the causes of which have not yet been fully understood - and familial - inherited within families from generation to generation, with a clear autosomal dominant transmission of mutations in Presenilin 1 (PSEN1), 2 (PSEN2) or Amyloid Precursors Protein (APP) genes. The main hallmark of AD consists of extracellular deposits of amyloid-beta (Aβ) peptide and intracellular deposits of the hyperphosphorylated form of the tau protein. An ever-growing body of research supports the viral infectious hypothesis of sporadic forms of AD. In particular, it has been shown that several herpes viruses (i.e., HHV-1, HHV-2, HHV-3 or varicella zoster virus, HHV-4 or Epstein Barr virus, HHV-5 or cytomegalovirus, HHV-6A and B, HHV-7), flaviviruses (i.e., Zika virus, Dengue fever virus, Japanese encephalitis virus) as well as Human Immunodeficiency Virus (HIV), hepatitis viruses (HAV, HBV, HCV, HDV, HEV), SARS-CoV2, Ljungan virus (LV), Influenza A virus and Borna disease virus, could increase the risk of AD. Here, we summarized and discussed these results. Based on these findings, significant issues for future studies are also put forward.

The association of herpes zoster and influenza vaccinations with the risk of developing dementia: a population-based cohort study within the UK Clinical Practice Research Datalink

BACKGROUND

Dementia affects ability to remember, think, or make decisions that interfere with doing everyday activities. There is no cure, therefore any prevention or delay of the onset is of importance. This study aims to investigate the association between zoster and influenza vaccinations and the risk of developing dementia.

METHODS

We conducted a retrospective population-based cohort study using electronic health records from 1469 general practices contributing to the Clinical Practice Research Datalink (CPRD) Aurum database with linked hospital episode statistics (HES) and Office for National Statistics (ONS) mortality records. We built two 'matched cohorts': zoster vaccine (854,745 exposed individuals) matched with 8.8 million comparators without a history of zoster vaccination, and influenza vaccine (742,487 exposed individuals) matched with 7.12 million comparators without a history of vaccination as another comparator group. The cohorts were then followed to assess the association of exposure (vaccine) with outcome (dementia diagnosis).

RESULTS

Zoster vaccination was associated with a lower risk of dementia diagnosis (adjusted hazard ratio (HR) 0.78 with 95% CI: 0.77-0.79), Alzheimer's diagnosis (adjusted HR 0.91 with 95% CI: 0.89-0.92 and other types of dementia (adjusted HR 0.71 with 95% CI: 0.69-0.72). Influenza vaccination also was associated with a slightly reduced hazard of dementia risk (adjusted HR 0.96 with 95% CI: 0.94-0.97).

CONCLUSION

Both zoster vaccine for prevention of shingles / herpes zoster and influenza vaccine to prevent influenza were associated with diminished risk of dementia, with the zoster association appearing more pronounced.

Antidepressant drugs use and epilepsy risk: A nationwide nested case-control study

BACKGROUND

To investigate the association between exposure to antidepressants (ADs) and the risk of epilepsy among patients exposed to ADs.

METHOD

We conducted a case-control study using Taiwan's National Health Insurance Research Database between 1998 and 2013. A total of 863 patients with epilepsy and 3,452 controls were included. The dose of ADs was categorized according to the cumulative defined daily dose (cDDD). The risk of epilepsy was assessed using conditional logistic regression analysis.

RESULTS

Compared with cDDD < 90, ADs exposure with cDDD > 365 (odds ratio [OR]: 1.37, 95% confidence interval [CI]:1.12-1.68) was associated with an increased risk of epilepsy, but not for those with cDDD 90-365 (OR: 1.07,95% CI: 0.87-1.30) after adjustment for several comorbidities and indications of ADs use. Other identified risk factors include cerebrovascular disease, traumatic brain injury, and central nervous system infection. Subgroup analysis of individual ADs showed that escitalopram (OR: 1.93, 95% CI: 1.12-3.31), venlafaxine (OR: 1.62, 95% CI: 1.13-2.31), mirtazapine (OR: 1.56, 95% CI: 1.00-2.43), paroxetine (OR: 1.44, 95% CI: 1.08-1.94), and fluoxetine (OR: 1.25, 95% CI: 1.01-1.56) had a significantly higher risk of epilepsy. Sertraline, fluvoxamine, citalopram, duloxetine, milnacipran, and bupropion did not show any proconvulsant effects.

CONCLUSIONS

The study found an increased risk of epilepsy among patients who were exposed to any ADs, particularly longer-term users. Given the nature of observational studies with residual bias, interpretation should be cautious.