Investigating the association between cancer and the risk of dementia: Results from the Memento cohort

Exploring the association between cancer and cognitive impairment in the Australian Imaging Biomarkers and Lifestyle (AIBL) study

An inverse association between cancer and Alzheimer's disease (AD) has been demonstrated; however, the association between cancer and mild cognitive impairment (MCI), and the association between cancer and cognitive decline are yet to be clarified. The AIBL dataset was used to address these knowledge gaps. The crude and adjusted odds ratios for MCI/AD and cognitive decline were compared between participants with/without cancer (referred to as C+ and C- participants). A 37% reduction in odds for AD was observed in C+ participants compared to C- participants after adjusting for all confounders. The overall risk for MCI and AD in C+ participants was reduced by 27% and 31%, respectively. The odds of cognitive decline from MCI to AD was reduced by 59% in C+ participants after adjusting for all confounders. The risk of cognitive decline from MCI to AD was halved in C+ participants. The estimated mean change in Clinical Dementia Rating-Sum of boxes (CDR-SOB) score per year was 0.23 units/year higher in C- participants than in C+ participants. Overall, an inverse association between cancer and MCI/AD was observed in AIBL, which is in line with previous reports. Importantly, an inverse association between cancer and cognitive decline has also been identified.

Oligomer-Aβ42 suppress glioma progression via potentiating phagocytosis of microglia

AIMS

Glioma is characterized by an immunosuppressed environment and a poor prognosis. The accumulation of Amyloid β (Aβ) leads to an active environment during the early stages of Alzheimer's disease (AD). Aβ is also present in glioma tissues; however, the biological and translational implications of Aβ in glioma are elusive.

METHODS

Immunohistochemical (IHC) staining, Kaplan-Meier (KM) survival analysis and Cox regression analysis on a cohort of 79 patients from our institution were performed to investigate the association between Aβ and the malignancy of glioma. Subsequently, the potential of oligomer-Aβ42 (OAβ42) to inhibit glioma growth was investigated in vivo and in vitro. Immunofluorescence staining and phagocytosis assays were performed to evaluate the activation of microglia. Finally, RNA-seq was utilized to identify the predominant signaling involved in this process and in vitro studies were performed to validate them.

RESULTS

A positive correlation between Aβ and a favorable prognosis was observed in glioma. Furthermore, OAβ42 suppressed glioma growth by enhancing the phagocytic activity of microglia. Insulin-like growth factor 1 (IGF-1) secreted by OAβ42-activated microglia was essential in the engulfment process.

CONCLUSION

Our study proved an anti-glioma effect of Aβ, and microglia could serve as a cellular target for treating glioma with OAβ42.

Association of Cancer History with Lifetime Risk of Dementia and Alzheimer's Disease

Background

The literature presents conflicting results regarding the potential protective effect of prevalent cancer on the development of dementia and Alzheimer's disease (AD).

Objective

Association between cancer and subsequent risk of dementia and/or AD was reported previously, but survival bias has been of concern. Here, we aimed to calculate the lifetime risk of dementia and AD and evaluate the association of cancer history with these two conditions.

Methods

In this retrospective analysis, we included 292,654 participants aged 60+ y during the follow-up and free of dementia at baseline, within the UK Biobank cohort. Lifetime risks of dementia and AD were estimated in individuals with and without cancer history, and different durations of cancer exposure and cancer types.

Results

During a median of 12.5 follow-up years, 5,044 new dementia and 2,141 AD cases were reported. Lifetime risks of dementia and AD were lower in cancer survivors compared to those without cancer, and this effect was more pronounced in participants with cancer history exposure≥5 years. Similar relationship was observed in individual cancer types, except for breast cancer.

Conclusions

Results suggested an inverse association between cancer history and lifetime risk of dementia and AD, which may be modified by different cancer types and cancer exposure time.

Association between multimorbidity status and incident dementia: a prospective cohort study of 245,483 participants

Multimorbidity (the presence of two or more long-term conditions [LTCs]) was suggested to exacerbate the neuronal injuries. The impact of multimorbidity on dementia has not been fully elucidated. We aimed to investigate the association between multimorbidity and dementia risk. We used the prospective data from 245,483 UK Biobank participants during a 9-year follow-up. Multimorbidity status was evaluated based on the LTC counts and multimorbidity patterns. Cox regression models adjusted for potential confounders were used to examine the associations of multimorbidity status with all-cause dementia (ACD), Alzheimer's disease (AD) and vascular dementia (VD). Participants with multimorbidity at baseline had higher risks of ACD and VD, and the risks were elevated with the increase of LTC counts (ACD: hazard ratios [HR] = 1.15, 95% confidence intervals [CI] = 1.01-1.31 with 2 LTCs; HR = 1.18, CI = 1.01-1.39 with 3 LTCs; HR = 1.65, CI = 1.44-1.88 with ≥4 LTCs; VD: HR = 1. 66, CI = 1.24-2.21 with 2 LTCs; HR = 2.10, CI = 1.53-2.88 with 3 LTCs; HR = 3.17, CI = 2.43-4.13 with ≥4 LTCs). Participants with ≥4 LTCs also had a higher risk of AD (HR = 1.34, CI = 1.08-1.66]. Participants with the cardio-cerebrovascular/respiratory/metabolic/musculoskeletal/depressive multimorbidity were 1.46, 1.28, and 2.50 times more likely to develop ACD (HR = 1.46, 95% CI = 1.28-1.67), AD (HR = 1.28, CI = 1.04-1.58), and VD (HR = 2.50, CI = 1.90-3.27), respectively. Those with tumor/genitourinary/digestive disorders had a 11% higher hazard of ACD (HR = 1.11, CI = 1.00-1.24) and a 73% elevated risk of VD (HR = 1.73, CI = 1.37-2.18). The prevention of LTC accumulation and the identification of specific multimorbidity patterns might be beneficial to the prevention of dementia and its subtypes, AD as well as VD.

Investigating the association between cancer and dementia risk: a longitudinal cohort study

BACKGROUND

Previous studies found that cancer survivors had a reduced risk of dementia compared with the general population. However, these findings were uncertain because of survivor bias and a lack of stratification by cancer types. This current cohort study used data from the UK Biobank to explore these associations.

METHODS

Multivariable Cox regression analyses were used to examine the association of cancer status and the risk of dementia with its subtypes after adjusting for age and sex. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated as a measure of relative risk by comparing observed dementia incidence among cancer patients.

RESULTS

We included 263,151 participants in the observational analysis. During a median follow-up of 9.18 years, dementia was diagnosed in 472 individuals with cancer and 3685 individuals without cancer, respectively. Cancer patients had lower risks of dementia (hazard ratio: 0.89, confidence interval: 0.81-0.98) and its subtypes (Alzheimer's disease [AD]: 0.85 [0.74-0.98]; vascular dementia [VD]: 0.81 [0.66-0.99]) in the Cox regression adjusted for age and sex. Individuals with cancers in the male genital system had substantially reduced risks of dementia (0.66 [0.46-0.93]) and AD (0.53 [0.29-0.97]) than those with cancers in other systems. Moreover, non-melanoma skin cancer and prostate cancer were associated with a reduced risk of dementia (0.79 [0.62-0.99]; 0.69 [0.49-0.97]), but not with AD or VD (P>0.05).

CONCLUSIONS

The current study supported a negative association between cancer and dementia risk, and encourages further exploration of the mechanistic basis of this inverse relationship to improve understanding.

Cancer diagnosis is associated with a lower burden of dementia and less Alzheimer's-type neuropathology

Cancer and Alzheimer's disease are common diseases in ageing populations. Previous research has reported a lower incidence of Alzheimer's disease-type (amnestic) dementia among individuals with a diagnosis of cancer. Both cancer and amnestic dementia are prevalent and potentially lethal clinical syndromes. The current study was conducted to investigate the association of cancer diagnosis with neuropathological and cognitive features of dementia. Data were analysed from longitudinally evaluated participants in a community-based cohort study of brain ageing who came to autopsy at the University of Kentucky Alzheimer's Disease Research Center. These data were linked to the Kentucky Cancer Registry, a population-based state cancer surveillance system, to obtain cancer-related data. We examined the relationship between cancer diagnosis, clinical dementia diagnosis, Mini-Mental State Examination scores and neuropathological features using inverse probability weighting to address bias due to confounding and missing data. To address bias due to inclusion of participants with dementia at cohort baseline, we repeated all analyses restricted to the participants who were cognitively normal at baseline. Included participants (n = 785) had a mean ± standard deviation age of death of 83.8 ± 8.6 years; 60.1% were female. Cancer diagnosis was determined in 190 (24.2%) participants, and a diagnosis of mild cognitive impairment or dementia was determined in 539 (68.7%). APOE ɛ4 allele dosage was lower among participants with cancer diagnosis compared to cancer-free participants overall (P = 0.0072); however, this association was not observed among those who were cognitively normal at baseline. Participants with cancer diagnosis had lower odds of mild cognitive impairment or dementia, and higher cognitive test scores (e.g. Mini-Mental State Examination scores evaluated 6 and ≤2 years ante-mortem, P < 0.001 for both comparisons). Cancer diagnosis also associated with lower odds of higher Braak neurofibrillary tangle stages (III/IV) or (V/VI), moderate/frequent neuritic plaques, moderate/frequent diffuse plaques and moderate/severe cerebral amyloid angiopathy (all P < 0.05). By contrast, TDP-43, α-synuclein and cerebrovascular pathologies were not associated with cancer diagnosis. Cancer diagnosis was associated with a lower burden of Alzheimer's disease pathology and less cognitive impairment. These findings from a community-based cohort with neuropathological confirmation of substrates support the hypothesis that there is an inverse relationship between cancer and Alzheimer's disease.

Risk of Dementia in Cancer Survivors: A Meta-Analysis of Population-Based Cohort Studies

Background: A negative association between cancer and Alzheimer’s disease (AD) was revealed. Objective: We aimed to further explore the dementia risk among cancer survivors and then among cancer survivors who received cancer treatment in subsequent subgroup analyses. Methods: Databases of PubMed, Embase, and Cochrane Library were systematically searched from inception to April 1, 2021, following PRISMA and MOOSE guidelines. Relative risks (RR) of dementia were pooled by a random-effects model stratifying the data by potential confounding factors to explore the heterogeneity. This study is registered with PROSPERO, number CRD42021250654. Results: A total of 36 studies were included in this meta-analysis, of which 16 studies were about the risk of dementia in cancer survivors, and 20 studies were about the risk of dementia in survivors who accepted cancer treatment. The pooled RR reached 0.89 ([95% CI = 0.82–0.97], I2 = 97.9%) for dementia and 0.89 ([0.83–0.95], I2 = 92.6%) for AD in cancer survivors compared with non-cancer controls. Notably, both dementia risk and AD risk significantly decreased in survivors of colon, leukemia, small intestine, and thyroid cancers (RR ranged from 0.64 to 0.92). Furthermore, prostate cancer patients treated with androgen deprivation therapy exhibited a significantly increased risk of dementia (RR:1.18 [1.09–1.27], I2 = 89.5%) and AD (RR:1.17 [1.08–1.25], I2 = 81.3%), with evidence of between-study heterogeneity. Conclusion: Currently, available evidence suggests that the risk of dementia among cancer survivors is decreased. However, large-scale prospective cohort studies are warranted to further prove the association.

Cardiac Troponin, Cognitive Function, and Dementia: A Systematic Review

Elevated cardiac troponin, a biomarker of myocardial injury, has been found in individuals with brain damage and lower cognitive function. We conducted a systematic review to examine the association of troponin with cognitive function, incidence of dementia and dementia-related outcomes. PubMed, Web of Science and EMBASE were searched from inception to August 2022. Inclusion criteria were: (i) population-based cohort studies; (ii) troponin measured as determinant; and (iii) cognitive function in any metric or diagnosis of any type of dementia or dementia-related measures as outcomes. Fourteen studies were identified and included, with a combined total of 38,286 participants. Of these studies, four examined dementia-related outcomes, eight studies examined cognitive function, and two studies examined both dementia-related outcomes and cognitive function. Studies report higher troponin to be associated with higher prevalence of cognitive impairment (n=1), incident dementia (n=1), increased risk of dementia hospitalization (specifically due to vascular dementia) (n=1), but not with incident Alzheimer's Disease (n=2). Majority of studies on cognitive function found elevated troponin also associated with worse global cognitive function (n=3), attention (n=2), reaction time (n=1) and visuomotor speed (n=1), both cross-sectionally and prospectively. Evidence regarding the association between higher troponin and memory, executive function, processing speed, language and visuospatial function was mixed. This was the first systematic review on the association between troponin, cognitive function, and dementia. Higher troponin is associated with subclinical cerebrovascular damage and might act as a risk-marker of cognitive vulnerability.

Investigating the association between cancer and the risk of dementia: Results from the Memento cohort

Introduction

Studies on the association of cancer and risk of dementia are inconclusive due to result heterogeneity and concerns of survivor bias and unmeasured confounding.

Methods

This study uses data from the Memento cohort, a French multicenter cohort following persons with either mild or isolated cognitive complaints for a median of 5 years. Illness‐death models (IDMs) were used to estimate transition‐specific hazard ratios (HRs) and 95% confidence intervals (CIs) for incident cancer in relation to dementia from time since study entry.

Results

The analytical sample (N = 2258) excluded 65 individuals without follow‐up information. At the end of follow‐up, 286 individuals were diagnosed with dementia, 166 with incident cancer, and 95 died. Incident cancer was associated with a reduced risk of dementia (HR = 0.58, 95% CI = 0.35‐0.97), with a corresponding E‐value of 2.84 (lower CI = 1.21).

Discussion

This study supports a protective relationship between incident cancer and dementia, encouraging further investigations to understand potential underlying mechanisms.