BACKGROUND:Visual impairment is a potential risk factor for depression and other outcomes in older adults. In population-based studies, vision can be measured using self-report or performance-based visual acuity, but epidemiologic associations often depend on which measure is used. METHODS:In this Research Practice article, we illustrate the use of propensity scores to harmonize analyses of self-reported and performance-based vision in older adults. Using 2021 data from the National Health and Aging Trends Study (NHATS; n = 2447), we measured associations between self-reported visual difficulty, distance visual impairment (logMAR >0.3), and depression. To harmonize self-reported and performance-based measures of vision, we modeled distance visual impairment as a function of self-reported vision and covariates and calculated exposure misclassification overlap weights. External validation was conducted using the Canadian Longitudinal Study on Aging (CLSA) and the Longitudinal Aging Study in India (LASI). RESULTS:Self-reported visual difficulty was associated with depression in NHATS (adjusted OR 2.32, 95% CI: 1.46-3.69), but distance visual impairment was not (OR 1.41, 95% CI: 0.99-2.01). After exposure misclassification overlap weighting, self-reported vision was no longer associated with depression, and results mirrored the association between distance visual impairment and depression (OR 1.49, 95% CI: 0.93-2.36). Similar findings were observed in CLSA and LASI. CONCLUSIONS:Associations between vision and depression in older adults differ according to how vision is measured. In studies that measure self-reported vision but not visual acuity, propensity score methods that leverage known relationships between the two can be used to approximate associations between reduced visual acuity and health outcomes.

Purpose:Retinal vascular changes could serve as an early, easily visible indicator of cerebrovascular health. Prior research on retinal vessel traits and stroke has predominantly focused on diameter, while vessel area and tortuosity remain underinvestigated and have yielded inconsistent results. Our goal was to examine longitudinal associations between retinal vessel traits and incident stroke. Design:Prospective cohort study. Participants:Baseline and 6-year follow-up data from the Canadian Longitudinal Study on Aging Comprehensive Cohort (n = 30 097) were used. Methods:A deep learning algorithm called Quantitative Analysis of Retinal Vessel Topology and Size extracted data from retinal images including arteriolar and venular diameter, area, and tortuosity. Participants were asked if a doctor had previously diagnosed them with stroke. Logistic regression was used to adjust for demographic, lifestyle, and clinical factors. Interactions with sex were also assessed. Main Outcome Measures:Stroke. Results:Having wider arterioles at baseline was associated with lower odds of stroke development over 6 years (odds ratio [OR] = 0.84, 95% confidence interval [CI]: 0.74‑0.95). Having larger venular area was associated with a higher odds of developing stroke (OR = 1.71, 95% CI: 1.11‑2.63), whereas larger arteriolar area showed the inverse association (OR = 0.62, 95% CI: 0.44‑0.86). Statistically significant interactions were found between sex and both arteriolar and venular tortuosity (P < 0.05). Conclusions:This study confirms that retinal vessel area and stroke are associated. Vessel area and arteriolar width are associated with the development of stroke, which may help to develop stroke prediction models in the future. Financial Disclosures:Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

BACKGROUND:Despite associations between atrial fibrillation (AF) and cognitive decline independent of stroke, pathways underlying this relationship remain unclear. Inflammatory markers, such as CRP (C-reactive protein), are associated with blood-brain barrier (BBB) permeability, potentially leading to neuroinflammation and neurodegeneration. We estimated associations of CRP with cognitive impairment and death in aging adults with AF. METHODS:Adults aged ≥45 years with prevalent AF and no cognitive impairment were identified from the REGARDS (Reasons for Geographic and Racial Differences in Stroke) cohort (N=30 239). Plasma CRP was measured at baseline and cognitive status measured annually using the Six-Item Screener. Competing risks Cox proportional hazards regression was used to estimate cause-specific hazard for cognitive impairment (Six-Item Screener score ≤3). Cognitive trajectories were identified using latent class growth models and adjusted binomial logistic regression used to estimate associations between CRP and cognitive trajectories, with interactions by sex. RESULTS:Among 2109 participants, 285 developed cognitive impairment and 786 died over a median 9-year follow-up. A doubling of baseline CRP levels was associated with increased death (hazard ratio [HR], 1.13 [95% CI, 1.08-1.19]) but not incident cognitive impairment (HR, 0.98 [95% CI, 0.91-1.04]). Latent class analyses identified 2 unique cognitive trajectories: 91% had a stable trajectory, while 9% showed progressive decline. Sex-specific models showed a 9% increased odds of progressive cognitive decline in men (odds ratio, 1.09 [95% CI, 1.01-1.17]) but not women (odds ratio, 1.04 [95% CI, 0.97-1.12]). CONCLUSIONS:Higher CRP was associated with cognitive impairment in aging men with AF, highlighting inflammation-mediated blood-brain barrier dysfunction as a potential pathway linking AF to cognitive decline.

High intraocular pressure (IOP) is an important risk factor for glaucoma, which is influenced by genetic and environmental factors. However, the etiology of high IOP remains uncertain. Metabolites are compounds involved in metabolism which provide a link between the internal (genetic) and external environments. O-methylascorbate has been reported to be associated with IOP. In addition, researchers have identified several genetic variants which are associated with metabolite concentrations, including O-methylascorbate and another vitamin C related metabolite, ascorbic acid 2-sulfate. We aimed to understand how O-methylascorbate and ascorbic acid 2-sulfate, or genetic variants associated with these metabolites, modify the associations between dietary environmental variables and IOP. We used data from 8060 participants of the Canadian Longitudinal Study on Aging. Using linear models adjusted for relevant covariates, we tested for interactions between six genetic variants previously found to be associated with O-methylascorbate and ascorbic acid 2-sulfate and four environmental variables related to diet (alcohol consumption frequency, smoking status, fruit consumption, and vegetable consumption). We also tested for interactions between serum concentrations of O-methylascorbate and ascorbic acid 2-sulfate and these environmental factors. We used a False Discovery Rate approach to correct for the 32 interaction tests performed. One interaction was suggestively significant after multiple testing correction (adjusted P-value < 0.1): rs8050812 and alcohol consumption frequency. Understanding how genetic variants and metabolites interact with the environment could shed light on biological pathways controlling IOP and lead to improved prevention and treatment of glaucoma.

PURPOSE. Age-related eye diseases are inconsistently associated with cognitive decline which could be due to effect modification. The purpose of this study was to investigate whether two genetic factors previously found to be associated with cognitive decline, the KIBRA (WWC1) and PDE7A/MTFR1 genes, modify the association between eye disease and cognitive function. METHODS. Data from a Montreal hospital-based cross-sectional study (n = 302) were used for the primary analysis. Candidate single-nucleotide polymorphisms (SNPs) rs17070145 (KIBRA gene) and rs10808746 (PDE7A/MTFR1 gene) were included in linear regression models to test for effect modification of the relationship between eye disease (glaucoma or age-related macular degeneration [AMD]) and cognitive function. Six oral cognitive tests were used. A replication analysis was done using the Quebec data from the Canadian Longitudinal Study on Aging (CLSA) (n = 4238). Effect modifications by expanded genomic regions around the candidate SNPs were tested. RESULTS. Three statistically significant interactions with two cognitive function measures -category verbal fluency and immediate story recall-were found in the Montreal study: glaucoma and AMD with rs17070145 and verbal fluency (P < 0.03) and glaucoma with rs10808746 with immediate story recall (P < 0.05). Similar interactions, although not with the same cognitive measure, were found in the CLSA: AMD with KIBRA and glaucoma with PDE7A/MTFR1. CONCLUSIONS. Our results suggest that the KIBRA and PDE7A/MTFR1 genes may modify the association between eye disease and cognitive function. This knowledge may help to better understand the mechanism by which glaucoma and AMD are related to cognitive function.

Purpose:To determine the factors cross-sectionally and longitudinally associated with retinal vessel diameter, total area, and tortuosity in the Canadian Longitudinal Study on Aging (CLSA). Methods:Of the 30,097 adults between ages 45 and 85 years old in the CLSA Comprehensive Cohort, 26,076 had at least one retinal image gradable by QUARTZ, a deep-learning algorithm that automatically assessed image quality, distinguished between arterioles and venules, and estimated retinal vessel traits over the entire retina. Questions were asked about demographic, lifestyle, and medical factors. Blood pressure, cholesterol, and C-reactive protein were measured. Participants returned for follow-up 3 years later. Multiple linear regression was used to provide adjusted estimates. Results:Current smoking was strongly associated with wider arteriolar and venular diameters and their widening over 3 years (P < 0.05). Current smoking was also associated with a larger arteriolar and venular area and a 3-year increase in venular area (P < 0.05). Obesity was positively associated with venular diameter, total venular area, 3-year change in total venular area, and venular tortuosity (P < 0.05). Diastolic blood pressure was negatively associated with both arteriolar and venular diameter, area, and tortuosity, both cross-sectionally and longitudinally (P < 0.05). Diabetes was associated with wider arteriolar diameters cross-sectionally, and type 1 diabetes was associated with 3-year widening of arteriolar diameters (P < 0.05). Conclusions:This work provides comprehensive information on the factors associated with retinal vessel traits and their change. Factors such as smoking, obesity, blood pressure, and diabetes were longitudinally related to retinal vessel traits, which play a role in the development of eye disease.

BACKGROUND:To cross-sectionally and longitudinally examine whether retinal vessel traits are associated with glaucoma-related outcomes (glaucoma, cup-to-disc ratio [CDR] and intraocular pressure [IOP]) and age-related macular degeneration (AMD). METHODS:Baseline and 3-year follow-up data from the 30 097 participants of the Canadian Longitudinal Study on Aging were used. The follow-up rate was 92%. QUARTZ, a deep learning algorithm, was used to extract data from retinal images including arteriolar and venular diameter, tortuosity and vertical CDR. Glaucoma and AMD were self-reported. IOP was measured. Multiple linear and logistic regression were used to adjust for demographic, lifestyle and clinical factors. RESULTS:Having wider arterioles was associated with a lower odds of glaucoma (OR = 0.36, 95% CI: 0.20, 0.65) at baseline but there was no association using longitudinal data. Instead, glaucoma at baseline was strongly associated with 3-year change in arteriolar diameter (β = -0.21, 95% CI: -0.37, -0.05) indicating that the cross-sectional association may have been due to reverse causality. Using longitudinal data, greater venular tortuosity was associated with a reduced 3-year development of glaucoma (OR = 0.52, 95% CI: 0.31, 0.87) and a 3-year reduction in the CDR (β = -0.006, 95% CI: -0.010, -0.002). Wider venular diameter was associated with a higher odds of AMD at baseline (OR = 2.77, 95% CI: 1.50, 5.15) and a higher odds of the 3-year development of AMD (OR = 4.15, 95% CI: 1.95, 8.82). CONCLUSIONS:Understanding the temporal relationship of changes in the retinal microvasculature and the development of eye disease may lead to better treatment and prevention strategies.

Retinal imaging offers a non-invasive means to assess the circulatory system, with morphological features of retinal vessels serving as biomarkers for systemic disease. QUARTZ (QUantitative Analysis of Retinal vessel Topology and siZe) is a fully automated artificial intelligence-enabled retinal vasculometry system designed to process large-scale retinal image datasets to obtain quantitative measures of vessel morphology for use in epidemiological studies. Previously reliant on traditional image processing and machine learning, QUARTZ has now transitioned to a deep learning pipeline. Currently individually trained versions are tailored to specific datasets. Evaluation using the UK Biobank retinal dataset shows improvements in performance metrics: the F1 score for vessel segmentation increased from 0.7753 to 0.8472, accuracy for the A/V segment-level decision increased from 0.8524 to 0.9022, the detection rate for optic disc localization increased from 0.9760 to 0.9933, and the F1 score for image quality classification increased from 0.8872 to 0.9750. QUARTZ distinguishes itself from other deep learning based retinal vasculometry systems through its efficient use of data, extracting valuable information despite issues such as low levels of illumination. The high performance of QUARTZ is consistent across two other extensive retinal datasets, namely the Canadian Longitudinal Study on Aging (CLSA) and the North East London Diabetic Eye Screening Programme (NEL DESP). Evaluation on subsets was preceded by the automatic processing of entire retinal datasets by QUARTZ, processing over 1.4 million images. These retinal vasculometry outputs will serve as a valuable resource for epidemiological studies.

Purpose:To determine whether self-reported race/ethnicity is associated with intraocular pressure (IOP) and glaucoma and to explore whether any associations are due to social, behavioral, genetic, or health differences. Design:Cross-sectional analysis of population-based data. Methods:We used the Canadian Longitudinal Study on Aging Comprehensive Cohort, which consists of 30,097 adults aged 45-85 years. Race/ethnicity was self-reported. Corneal-compensated intraocular pressure (IOP) was measured in mmHg using the Reichert Ocular Response Analyzer. Participants were asked to report if they have ever had a diagnosis of glaucoma and whether they used eye care in the past year. A glaucoma polygenic risk score (PRS) was calculated. Logistic and linear regression models were used. Results:Black individuals had higher mean IOP levels (beta coefficient (β) = 1.46; 95% confidence interval [CI], 0.62, 2.30) while Chinese, Japanese and Korean (β = -1.00; 95% CI, -1.63, -0.38) and Southeast Asian and Filipino individuals (β = -1.56; 95% CI, -2.68, -0.43) had lower mean IOP levels as compared to White individuals after adjustment for sociodemographic, behavioral, genetic, and health-related variables. Black people were more likely to report glaucoma as compared to White people after adjustment (odds ratio [OR] = 2.43; 95% CI, 1.27, 4.64). Conclusion:Racial and ethnic differences in IOP and glaucoma were identified. Adjusting for sociodemographic, behavioral, genetic, and health-related variables did not fully explain these differences. Longitudinal research is needed to further explore the reasons for these differences and to understand their relevance to disease pathogenesis and progression.

OBJECTIVE:To examine the employment status of those with and without visual impairment and eye disease and to examine the association between visual impairment and eye disease and a reduction in income over a 3-year period. DESIGN:Population-based prospective cohort study. PARTICIPANTS:A total of 12,174 nonretired participants aged 45-64 years old in the Canadian Longitudinal Study on Aging. METHODS:Visual impairment was defined if binocular presenting or pinhole-corrected monocular visual acuity in the better eye was worse than 20/40 at baseline. Self-reported diagnoses of age-related macular degeneration (AMD) and glaucoma were collected. Employment status (employed, not employed due to sickness or disability, or unemployed) was based on questions on labour force participation. Income reduction was defined as household income <$50,000 per year at follow-up when household income was ≥$50,000 at baseline. Multinomial and logistic regressions were used to adjust for demographic and health variables. RESULTS:Visual impairment using binocular presenting visual acuity (odds ratio [OR] = 2.09; 95% CI, 1.21-3.62) and pinhole-corrected visual acuity (OR = 2.99; 95% CI, 1.54-5.83) were associated with a higher odds of not being employed due to sickness or disability after adjustment. AMD (OR = 1.82; 95% CI, 1.11-3.01) and glaucoma (OR = 2.05; 95% CI, 1.28-3.28) at baseline were both associated with reductions in income over a 3-year period after adjustment. CONCLUSION:Individuals with visual impairment experienced lower employment, and those with AMD or glaucoma were more likely to have their incomes decline over 3 years. Policies to improve workplace participation by those with vision loss are needed.

Introduction: Vitamin C is an essential nutrient. Sex differences in serum vitamin C concentrations have been observed but are not fully known. Investigation of levels of metabolites may help shed light on how dietary and other environmental exposures interact with molecular processes. O-methylascorbate and ascorbic acid 2-sulfate are two metabolites in the vitamin C metabolic pathway. Past research has found genetic factors that influence the levels of these two metabolites. Therefore, we investigated possible effect modification by sex of genetic variant-metabolite associations and characterized the biological function of these interactions.Methods: We included individuals of European descent from the Canadian Longitudinal Study on Aging with available genetic and metabolic data (n = 9004). We used linear mixed models to tests for genome-wide associations with O-methylascorbate and ascorbic acid 2-sulfate, with and without a sex interaction. We also investigated the biological function of the important genetic variant-sex interactions found for each metabolite.Results: Two genome-wide statistically significant (p value < 5 × 10−8) interaction effects and several suggestive (p value < 10–5) interaction effects were found. These suggestive interaction effects were mapped to several genes including HSD11B2, associated with sex hormones, and AGRP, associated with hunger drive. The genes mapped to O-methylascorbate were differently expressed in the testis tissues, and the genes mapped to ascorbic acid 2-sulfate were differently expressed in stomach tissues.Discussion: By understanding the genetic factors that impact metabolites associated with vitamin C, we can better understand its function in disease risk and the mechanisms behind sex differences in vitamin C concentrations.

Atrial fibrillation (AF) increases risk of cognitive decline independent of stroke, but mechanisms remain unclear. Elevated levels of peripheral inflammatory markers common in AF are associated with increased blood-brain barrier (BBB) permeability and may contribute to neuroinflammation and degeneration. To examine the role of these markers in dementia risk, we estimated associations of plasma C-reactive protein (CRP), interleukin-6 (IL-6), and fibrinogen with dementia and cognitive decline in aging adults with and without AF. Dementia free adults aged ≥ 65 years were identified from the Cardiovascular Health Cognition Study. Exposures were plasma CRP, IL-6, and fibrinogen at baseline and follow-up and primary outcomes were dementia and cognitive function, measured and adjudicated annually with the Modified Mini-Mental State Examination (3MS). Competing risks Cox proportional hazards regression was used to estimate associations between time-varying exposures and dementia. Latent class growth models were used to identify cognitive trajectories adjusted binomial logistic regression to test associations between these trajectories and baseline markers. All models were stratified by AF status, with interaction terms for sex and apolipoprotein E (APOE) ε4 status. Among 3,375 adults (505 with AF and 2,870 without), 480 developed dementia over a median follow-up of 9.3 years. No associations between inflammatory markers and dementia hazard were observed, but latent class analyses identified two unique cognitive trajectories, with 82% showing a stable trajectory and 18% showing rapidly progressing decline. Among those with AF, elevated CRP and IL-6 increased the odds of cognitive decline by 10% (95% CI 1.05 – 1.15) and 32% (95% CI 1.22 – 1.44), respectively. Sex-specific models indicated that a 1g/L increase in fibrinogen increased the odds of cognitive decline by 57% among females with AF only (95% CI 1.36-1.81). Among those with AF, inflammatory markers were more positively associated with cognitive decline in the presence of the APOE ε4 allele. Elevated IL-6 was associated with cognitive decline in aging adults both with and without AF and elevated CRP and fibrinogen were associated with cognitive decline in those with AF only. Critically, sex and APOE genotype significantly modified these associations. Future work using more sensitive markers of central inflammation is needed.

PURPOSE:To understand the relationship between ambient air pollution and the onset of balance problems. DESIGN:Population-based prospective cohort study. METHODS:Baseline and 3-year follow-up data were used from the Canadian Longitudinal Study on Aging. The Comprehensive Cohort included adults aged 45-85 years old recruited from 11 sites across 7 provinces. Data on air pollution came from the Canadian Urban Environmental Health Research Consortium. Annual mean levels of ozone, fine particulate matter (PM2.5), and sulfur dioxide for each participant's postal code were estimated from satellite data. Balance was measured at both time points using the one-leg balance test with those who could not stand on one leg for at least 60 s defined as failing the balance test. Our outcome was the new development of failing the balance test at follow-up in those who passed the balance test at baseline. Logistic regression was used. RESULTS:Of the 12,158 people who could stand for 60 s on one leg at baseline, 18% were unable to do so 3 years later. In single pollutant models, living in an area with higher ozone levels was associated with the 3-year onset of balance problems (odds ratio (OR) = 1.13 per interquartile range of ozone, 95% CI 1.02, 1.24) after adjustment for demographic, lifestyle, and health variables. In a multipollutant model, the association with ozone increased slightly (OR = 1.16, 95% CI 1.04, 1.30). There were no associations with PM2.5 or sulfur dioxide. CONCLUSION:Our findings provide longitudinal evidence that higher ozone levels are associated with the odds of developing balance problems over a 3-year period. Further work should attempt to confirm our findings and explore the potential mechanism of action.

The coronavirus disease 2019 (COVID-19) pandemic disrupted the practice of medicine, causing stress and uncertainty among ophthalmologists. This cross-sectional, survey-based study of Canadian Ophthalmological Society members (n = 1152) aims to report on Canadian ophthalmologists’ mental health during the COVID-19 pandemic. Four questionnaires were administered between December 2020 and May 2021: the Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), the 7-item Insomnia Severity Index (ISI), and the Impact of Event Scale—Revised (IES-R). From all of the responses, 60/85 answers were deemed complete and were included. The median age was 50–59 years and 53% were women. On PHQ-9, most respondents had no or minimal depressive symptoms (n = 38, 63%), while 12% (n = 7) had moderately severe depressive symptoms and 12% (n = 7) reported impaired daily functioning and/or thoughts of suicide or self-harm. On the GAD-7 scale, 65% (n = 39) had no significant anxiety, while 13% (n = 8) had moderate to severe anxiety. Most respondents did not have clinically significant insomnia (n = 41, 68%). Finally, 16 respondents (27%) had an IES-R score ≥24 suggesting possible post-traumatic stress disorder. No significant differences were found based on demographics. During the COVID-19 pandemic, up to 40% of respondents experienced varying degrees of depression, anxiety, insomnia, and distress from the event. In 12%, there were concerns for impaired daily functioning and/or suicidal thoughts.

SUMMARY:Founder populations with deep genealogical data are well suited for investigating genetic variants contributing to diseases. Here, we present a major update of the genealogical analysis R package GENLIB, centered around a new function which can simulate the transmission of haplotypes from founders to probands along very large and complex user-specified genealogies.AVAILABILITY AND IMPLEMENTATION:The latest update of the GENLIB package (v1.1.9) contains the new gen.simuHaplo() function and is available on the CRAN repository and from https://github.com/R-GENLIB/GENLIB. Examples can be accessed at https://github.com/R-GENLIB/simuhaplo_functions.

Purpose: The purpose of this study was to examine the association of alcohol consumption with intraocular pressure (IOP) and glaucoma and to assess whether any associations are modified by a glaucoma polygenic risk score (PRS). Methods: Cross-sectional analysis of data from the Canadian Longitudinal Study on Aging Comprehensive Cohort, consisting of 30,097 adults ages 45 to 85 years, was done. Data were collected from 2012 to 2015. Alcohol consumption frequency (never, occasional, weekly, and daily) and type (red wine, white wine, beer, liquor, and other) were measured by an interviewer-administered questionnaire. Total alcohol intake (grams/week) was estimated. IOP was measured in mm Hg using the Reichert Ocular Response Analyzer. Participants reported a diagnosis of glaucoma from a doctor. Logistic and linear regression models were used to adjust for demographic, behavioral, and health variables. Results: Daily drinkers had higher IOP compared to those who never drank (β = 0.45, 95% confidence interval (CI) = 0.05, 0.86). An increase in total weekly alcohol intake (per 5 drinks) was also associated with higher IOP (β = 0.20, 95% CI = 0.15, 0.26). The association between total alcohol intake and IOP was stronger in those with a higher genetic risk of glaucoma (P for interaction term = 0.041). There were 1525 people who reported being diagnosed with glaucoma. Alcohol consumption frequency and total alcohol intake were not associated with glaucoma. Conclusions: Alcohol frequency and total alcohol intake were associated with elevated IOP but not with glaucoma. The PRS modified the association between total alcohol intake and IOP. Findings should be confirmed in longitudinal analyses.

The COVID-19 pandemic had significant impacts on the mental and visual health of patients. This cross-sectional, survey-based, multicentric study evaluates the state of mental and visual health among patients with chronic ocular diseases such as glaucoma, neovascular age-related macular degeneration, diabetic retinopathy, or chronic uveitis during the lockdown period of the COVID-19 pandemic. Mental health was assessed using three questionnaires: the Patient Health Questionnaire-9 (PHQ-9), the Impact of Event Scale-Revised (IES-R), and the National Eye Institute Visual Function Questionnaire-25 (VFQ-25). A total of 145 patients completed the questionnaires. The PHQ-9 showed that most respondents (n = 89, 61%) had none or minimal depressive symptoms, while 31 (21%) had mild depressive symptoms, 19 (13%) had moderate depressive symptoms, 5 (3%) had moderately severe depressive symptoms, and 1 (1%) had severe depressive symptoms. Regarding stress surrounding the pandemic, the median IES-R showed mild distress in 16 (11%), moderate distress in 7 (5%), and severe distress in 4 (3%). The COVID-19 pandemic lockdowns had a negative impact on patients' mental health with close to 20% of the patients reporting at least moderately depressive symptoms and 19% reporting at least mildly distressful symptoms.

Research on the genetics of complex traits overwhelmingly focuses on the additive effects of genes. Yet, animal studies have shown that non-additive effects, in particular homozygosity effects, can shape complex traits. Recent investigations in human studies found some significant homozygosity effects. However, most human populations display restricted ranges of homozygosity by descent (HBD), making the identification of homozygosity effects challenging. Founder populations give rise to higher HBD levels. When deep genealogical data are available in a founder population, it is possible to gain information on the time to the most recent common ancestor (MRCA) from whom a chromosomal segment has been transmitted to both parents of an individual and in turn to that individual. This information on the time to MRCA can be combined with the time to MRCA inferred from coalescent models of gene genealogies. HBD can also be estimated from genomic data. The extent to which the genomic HBD measures correspond to the genealogical/coalescent measures has not been documented in founder populations with extensive genealogical data. In this study, we used simulations to relate genomic and genealogical/coalescent HBD measures. We based our simulations on genealogical data from two ongoing studies from the French-Canadian founder population displaying different levels of inbreeding. We simulated single-nucleotide polymorphisms (SNPs) in a 1-Mb genomic segment from a coalescent model in conjunction with the observed genealogical data. We compared genealogical/coalescent HBD to two genomic methods of HBD estimation based on hidden Markov models (HMMs). We found that genomic estimates of HBD correlated well with genealogical/coalescent HBD measures in both study genealogies. We described generation time to coalescence in terms of genomic HBD estimates and found a large variability in generation time captured by genomic HBD when considering each SNP. However, SNPs in longer segments were more likely to capture recent time to coalescence, as expected. Our study suggests that estimating the coalescent gene genealogy from the genomic data to use in conjunction with observed genealogical data could provide valuable information on HBD.