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

Risk of Dementia in Different Types of Cancer Survivors: A Nationwide Cohort Study

OBJECTIVES

The association between specific types of malignancies and the subsequent risk of dementia remains unknown.

DESIGN

A retrospective population-based cohort study based on data from Taiwan National Health Insurance Research Database.

SETTING AND PARTICIPANTS

We recruited 32,250 patients who survived malignancies and 322,500 controls between 1998 and 2011 and followed them up until the end of 2013.

MEASUREMENTS

Diagnoses of dementia (including Alzheimer's disease (AD), vascular dementia (VaD), and unspecified dementia) was made during the follow-up period. Cox regression analyses were performed after adjusting for potential confounders. A sensitivity analysis was conducted to exclude patients with prodromal dementia.

RESULTS

Cancer survivors were more likely to develop AD (hazard ratio [HR]: 1.68, 95% confidence interval [CI]: 1.38-2.06), unspecified dementia (HR: 1.19, 95% CI: 1.07-1.32), and any dementia (HR: 1.26, 95% CI: 1.16-1.37) compared with controls after adjusting for potential confounders. Importantly, cancers of the digestive and genitourinary organs seem to be associated with AD, unspecified dementia, and any dementia, whereas only malignant neoplasms of the brain are more likely to develop into VaD. Sensitivity analyses after exclusion of the first three or five years of observation and after exclusion of case enrollment before 2009 or 2007 showed consistent findings.

CONCLUSION

Cancer survivors are at higher risk of subsequent dementia. Different types of cancer survivors may contribute to variable risks of specific dementias. Further studies are necessary to investigate the underlying mechanisms in cancer survivors and patients with dementia.

Unraveling the bidirectional link between cancer and dementia and the impact of cancer therapies on dementia risk: A systematic review and meta-analysis

Observational studies on the cancer-dementia relationship have yielded controversial results. This study systematically reviews the evidence to clarify this association. We searched Embase, Global Health, Ovid Medline, and APA PsycInfo. Colorectal and lung cancers showed the greatest risk reduction for all-cause dementia (ACD) and Alzheimer's disease (AD), respectively, while melanoma and colorectal cancers had the largest reduction in vascular dementia (VaD). Prostate cancer survivors on androgen deprivation therapy (ADT) had a higher risk of ACD/AD, while breast cancer patients on tamoxifen had a lower AD risk. Chemotherapy was linked to a reduced AD risk. ACD patients saw a 30% risk reduction for bladder, colorectal, and lung cancers, while AD patients had a ≈ 35% reduction for bladder and lung cancers. Our study urges clinicians to monitor cognitive function in cancer patients, especially those on ADT, tamoxifen, or chemotherapy and highlights the need for research into cancer-dementia mechanisms. HIGHLIGHTS: Cancer survivors have an 8% to 14% lower risk of dementia, while those with dementia have a 25% lower cancer risk. Colorectal and non-melanoma skin cancers were associated with reduced risks of all-cause dementia (ACD; 16%/9%), Alzheimer's disease (AD; 13%/5%), and vascular dementia (VaD; 24%/9%). Lung cancer reduced AD risk by 17%, and melanoma reduced VaD risk by 27%. ACD and AD patients had lower risks of lung (30%/36%), bladder (32%/34%), breast (26%/20%), and colorectal (31%/28%) cancers. Tamoxifen and chemotherapy reduced AD risk, while androgen deprivation therapy increased ACD risk.

Dementia Incidence in Survivors of Multiple Myeloma: A National Case-Control Study Conducted in Korea (The CAREMM-2106 Study)

BACKGROUND

Dementia, a growing global health issue, affects older adults and specific groups like long-term cancer survivors. The link between cancer survival and dementia is debated. Multiple myeloma (MM), a common blood cancer in older adults, is often linked with cognitive issues. This study investigated dementia incidence in long-term MM survivors using Korean national data.

METHODS

A retrospective case-control study used data from the Korea National Health Insurance Service (KNHIS), covering about 50 million Koreans. Patients diagnosed with MM between 2009 and 2020 formed the case cohort, while the control cohort included matched individuals without MM using propensity-score matching. Analyzing baseline characteristics, comorbidities, and socioeconomic status, the primary outcome was dementia incidence identified via ICD-10 codes. Statistical methods included Kaplan-Meier plots, cause-specific and Fine-Gray subdistribution hazard models, and a 3-year landmark analysis for immortal time bias.

RESULTS

The study included 33,864 patients, with 16,932 in each cohort. The overall cumulative dementia incidence was lower in the MM cohort compared to controls. However, in the first 3 years, MM patients had a higher dementia risk (HR: 1.711, 95% CI, 1.562-1.874) than controls. After 3 years, the risk significantly decreased (HR: 0.625, 95% CI, 0.560-0.696). Age-specific analysis showed a consistent pattern, particularly among MM patients aged 70-79, where dementia risk increased post-3 years.

CONCLUSION

This study reveals a lower long-term dementia risk in MM survivors compared to non-MM individuals. Further prospective studies are needed to confirm these findings and explore the underlying mechanisms.

Is incident cancer in later life associated with lower incidence of dementia?

Cancer has been associated with lower risk of dementia, although methodological issues raise concerns about the validity of this association. We recruited 31,080 men aged 65-85 years who were free of cancer and dementia, and followed them for up to 22 years. We used health record linkage to identify incident cases of cancer and dementia, and split time span to investigate this association. 18,693 (60.1%) and 6897 (22.2%) participants developed cancer and dementia during follow-up. The hazard ratio (HR) of dementia associated with cancer was 1.13 (95% CI = 1.07, 1.20) and dropped to 0.85 (95% CI = 0.80, 0.91) when 449 participants who developed dementia within 2 years were excluded. The diagnosis of cancer seems to facilitate the early detection of dementia cases. Older participants who survive cancer for 2 or more years have lower risk of receiving the diagnosis of dementia over time. The factors that mediate this association remain unclear.

The inverse association between cancer history and incident cognitive impairment: Addressing attrition bias

INTRODUCTION

Cancer is inversely associated with cognitive impairment. Whether this is due to statistical handling of attrition (death and censoring) is unknown.

METHODS

We quantified associations between cancer history and incident cognitive impairment among Health, Aging, and Body Composition Study participants without baseline cognitive impairment or stroke (n = 2604) using multiple competing-risks models and their corresponding estimands: cause-specific, subdistribution, and marginal hazards, plus composite-outcome (cognitive impairment or all-cause mortality) hazards. All-cause mortality was also modeled.

RESULTS

After covariate adjustment (demographics, apolipoprotein E ε4, lifestyle, health conditions), cause-specific and marginal hazard ratios (HRs) were similar to each other (≈ 0.84; P values < 0.05). The subdistribution HR was 0.764 (95% confidence interval [CI] = 0.645-0.906), and composite-outcome Cox model HR was 1.149 (95% CI = 1.016-1.299). Cancer history was positively associated with all-cause mortality (HR = 1.813; 95% CI = 1.525-2.156).

DISCUSSION

Cause-specific, subdistribution, and marginal hazards models produced inverse associations between cancer and cognitive impairment. Competing risk models answer slightly different questions, and estimand choice influenced findings here.

HIGHLIGHTS

Cancer history is inversely associated with incident cognitive impairment. Findings were robust to handling of competing risks of death. All models also addressed possible informative censoring bias. Cancer history was associated with 16% lower hazard of cognitive impairment. Cancer history was associated with 81% higher all-cause mortality hazard.

A study of long-term supraphysiologic-dose anabolic-androgenic steroid use on cognitive function in middle-aged men

Background: Long-term use of supraphysiologic doses of anabolic-androgenic steroids (AAS) has been associated with impaired visuospatial memory in young men but little is known about its cognitive effects in middle-aged men.Objectives: We compared cognition in middle-aged men with histories of long-term AAS use and age-matched non-users.Methods: We administered cognitive tests from the CANTAB battery to 76 weightlifters aged 37-60 years (mean [SD] 48.5 [6.5] years), of whom 51 reported at least 2 years of cumulative AAS use and 25 reported no AAS exposure.Results: We found no significant AAS user versus non-user group differences on visuospatial, verbal memory, emotional recognition, or executive function tasks (corrected p's ≥ .00089; effect sizes ≤ .5).Conclusions: Our null visuospatial task findings contrast with our prior younger cohort study (mean age 37.1 [7.1] years), in which we found impaired visuospatial task performance in people who use AAS, and with other reports of cognitive impairments in younger men use AAS. Men who use AAS may develop early visuospatial memory deficits that stabilize by middle age while middle-aged non-users' performance may "catch up" due to normal age-related visuospatial declines. Similar effects could contribute to our null findings on other tasks. Between-study cohort substance use differences or environmental factor differences that modify cognition, such as study geographical location and time of year, also could contribute to our discordant findings. Since young adult male AAS users experience increased mortality from unnatural causes, improving our understanding of AAS cognitive effects in this age group is important.

Dementia incidence varied by anticancer drugs and molecular targeted therapy in a population-based cohort study

Anticancer drugs may affect the incidence of dementia by modulating the common pathophysiology between cancer and dementia. However, there is a paucity of research that focused on anticancer drugs with different mechanisms of action and their associations with subtypes of dementia. Therefore, we aimed to investigate the incidence of dementia according to various groups of anticancer drugs. From the Korea National Health Insurance Service database, our retrospective population-based cohort study enrolled 116,506 cancer patients aged 65 years and older who received anticancer drugs between January 1, 2008 and December 31, 2018. The hazard ratio was determined using Cox proportional hazards regression models, comparing each group of anticancer drugs to all other anticancer drugs, after adjusting for covariates. Antimetabolites (HR = 0.91; 95% CI 0.84-0.97) and molecular targeted therapies (HR = 0.60; 95% CI 0.49-0.74) were associated with a decreased incidence of dementia of the Alzheimer type (DAT), but not with vascular dementia. Among molecular targeted therapies, epidermal growth factor receptor inhibitors (HR = 0.60; 95% CI 0.46-0.79) and multikinase inhibitors (HR = 0.49; 95% CI 0.27-0.89) were associated with a low incidence of DAT only. Our findings highlight the potential for targeted repurposing of anticancer drugs to prevent dementia.

Dispensing of antineoplastic medications and their impact on the dispensing of anti-dementia drugs for adults aged ≥60 years: A cohort study

History of cancer has been associated with decreased risk of dementia, but it is unclear if this is due to the use of antineoplastic medications. Participants were 442,795 adults aged ≥60 years, of whom 235,841 (53.26 %) were women. Those dispensed antineoplastic medications during 2012-2013 had lower odds of being dispensed an anti-dementia drug between 2015 and 2021 (age/sex-adjusted OR = 0.60, 95%CI = 0.55-0.66). The dispensing of antineoplastic medications was associated with an adjusted hazard ratio of 0.72 (95%CI = 0.65-0.80) of subsequent dispensing of an anti-dementia drug. Understanding the mechanisms that support this association may contribute to the introduction of novel approaches to dementia prevention.

The association between BCG treatment in patients with bladder cancer and subsequent risk of developing Alzheimer and other dementia.-A Swedish nationwide cohort study from 1997 to 2019

BACKGROUND

Alzheimer's disease (AD) affects 50 million people worldwide. The immune system plays a major role in the pathogenesis of AD. Several retrospective analyses have reported a decreased risk of AD and other dementias in bladder cancer patients treated with immunotherapy in the form of Bacillus Calmette-Guerin (BCG) bladder instillations. We tested this hypothesis in a Swedish population-based prospective cohort of patients with non-muscle invasive bladder cancer (NMIBC).

METHODS AND FINDINGS

We utilized the BladderBaSe 2.0 database, which contains tumor-specific, health-related, and socio-demographic information for patients diagnosed with NMIBC between 1997 and 2019. The database also includes a matched comparison cohort sampled from the general population, consisting of individuals free from urinary tract cancer at the time of the index case's diagnosis. Five controls were randomly selected for each index case without replacement on the date of the index case's diagnosis. Our inclusion criteria identified participants diagnosed with NMIBC who had received BCG as primary treatment, along with their corresponding comparison cohort. We excluded those diagnosed with dementia before or within 6 months of NMIBC diagnosis. To compare the NMIBC cohort with their matched comparison cohort, we used a stratified Cox model, treating each case with its controls as a stratum. We identified 38,934 patients in the NMIBC cohort, with 6,496 receiving BCG after primary diagnosis (cases). AD/dementia was diagnosed during follow-up in 6.1% of cases and 7.4% of controls. Cases had a slightly lower risk of dementia than controls, with a hazard ratio (HR) of 0.88 (95% confidence interval [CI] 0.780-0.991), and a HR of 0.89 (CI 0.703-1.119) for AD. Subgroup analysis for dementia showed that age over 75 years had an HR of 0.73 (CI 0.616-0.863), and female gender had an HR of 0.73 (CI 0.552-0.971). The associations were similar for AD specifically, but not statistically significant. Similar to previous studies, we analyzed bladder cancer patients treated with and without BCG therapy. Multivariate Cox analysis indicated that those treated with BCG had a lower risk of dementia (HR 0.81, 95% CI 0.71-0.92), and an HR of 0.98 (95% CI 0.75-1.27) for AD specifically. High age was a significant risk modifier; the HR was 3.8 (CI 3.44-4.11) for dementia and 3.1 (CI 2.59-3.73) for AD. Even patients not receiving BCG had a significantly lower risk for AD than controls (HR 0.86, CI 0.77-0.96).

CONCLUSIONS

This study observed a marginally decreased risk of developing AD/dementia associated with earlier intravesical BCG treatment in NMIBC patients. This small benefit was most pronounced in those with high age and female gender. The disparity from previous highly positive studies underscores the importance of using an appropriate control cohort.

The Spectrum of Alzheimer-Type Pathology in Cognitively Normal Individuals

BACKGROUND

The strongest risk factor for the development of Alzheimer's disease (AD) is age. The progression of Braak stage and Thal phase with age has been demonstrated. However, prior studies did not include cognitive status.

OBJECTIVE

We set out to define normative values for Alzheimer-type pathologic changes in individuals without cognitive decline, and then define levels that would qualify them to be resistant to or resilient against these changes.

METHODS

Utilizing neuropathology data obtained from the National Alzheimer's Coordinating Center (NACC), we demonstrate the age-related progression of Alzheimer-type pathologic changes in cognitively normal individuals (CDR = 0, n = 542). With plots generated from these data, we establish standard lines that may be utilized to measure the extent to which an individual's Alzheimer-type pathology varies from the estimated normal range of pathology.

RESULTS

Although Braak stage and Thal phase progressively increase with age in cognitively normal individuals, the Consortium to Establish a Registry for Alzheimer's Disease neuritic plaque score and Alzheimer's disease neuropathologic change remain at low levels.

CONCLUSION

These findings suggest that an increasing burden of neuritic plaques is a strong predictor of cognitive decline, whereas, neurofibrillary degeneration and amyloid-β (diffuse) plaque deposition, both to some degree, are normal pathologic changes of aging that occur in almost all individuals regardless of cognitive status. Furthermore, we have defined the amount of neuropathologic change in cognitively normal individuals that would qualify them to be "resilient" against the pathology (significantly above the normative values for age, but still cognitively normal) or "resistant" to the development of pathology (significantly below the normative values for age).