Centre de recherche sur le vieillissement

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder characterized by extracellular amyloid β (Aβ) and intraneuronal tau protein aggregations. One risk factor for developing AD is the APOE gene coding for the apolipoprotein E protein (apoE). Humans have three versions of APOE gene: ε2, ε3, and ε4 allele. Carrying the ε4 allele is an AD risk factor while carrying the ε2 allele is protective. ApoE is a component of lipoprotein particles in the plasma at the periphery, as well as in the cerebrospinal fluid (CSF) and in the interstitial fluid (ISF) of brain parenchyma in the central nervous system (CNS). ApoE is a major lipid transporter that plays a pivotal role in the development, maintenance, and repair of the CNS, and that regulates multiple important signaling pathways. This review will focus on the critical role of apoE in AD pathogenesis and some of the currently apoE-based therapeutics developed in the treatment of AD.

It is well known that the immune response decreases during aging, leading to a higher susceptibility to infections, cancers and autoimmune disorders. Most widely studied have been alterations in the adaptive immune response. Recently, the role of the innate immune response as a first-line defence against bacterial invasion and as a modulator of the adaptive immune response has become more widely recognized. One of the most important cell components of the innate response is neutrophils and it is therefore important to elucidate their function during aging. With aging there is an alteration of the receptor-driven functions of human neutrophils, such as superoxide anion production, chemotaxis and apoptosis. One of the alterations underlying these functional changes is a decrease in signalling elicited by specific receptors. Alterations were also found in the neutrophil membrane lipid rafts. These alterations in neutrophil functions and signal transduction that occur during aging might contribute to the significant increase in infections in old age.

A recent review suggested that self-compassion promotes use of adaptive rather than maladaptive coping. Less is known about how self-compassion is linked to stress and coping in the context of a chronic stressor. Across two primarily female chronic illness samples, inflammatory bowel disease (N = 155) and arthritis (N = 164), a model linking self-compassion to lower stress through coping styles and coping efficacy was tested. Path analyses revealed significant indirect effects for adaptive coping styles (active, positive reframing, and acceptance), and negatively for maladaptive coping styles (behavioral disengagement and self-blame) in both samples. Findings suggest that the relative balance of adaptive and maladaptive coping strategies used by self-compassionate people is associated with better coping outcomes in the context of chronic illness.

STUDY OBJECTIVES: To examine in cognitively intact older men and women the associations between subjective sleep quality and 1-yr incident cognitive impairment. DESIGN: Prospective cohort study. SETTING: General community. PARTICIPANTS: 1,664 cognitively intact individuals age 65 to 96 years. MEASUREMENTS AND RESULTS: Sleep quality at baseline was measured using the Pittsburgh Sleep Quality Index (PSQI). Cognitive functioning was assessed at baseline and 12 months later using the Mini-Mental State Examination (MMSE). Incident general cognitive impairment was defined according to a follow-up MMSE score below the 15(th) percentile according to normative data and of at least 2 points below baseline. General cognitive impairments were also separated into amnestic and nonamnestic subtypes according to MMSE delayed recall performance. Associations between sleep quality indicators at baseline and incident cognitive impairment were assessed by odds ratio (OR) adjusted for age, education, baseline MMSE score, psychotropic drug use, anxiety, depressive episodes, cardiovascular conditions, and chronic diseases. Results revealed that global PSQI score was significantly linked with incident cognitive impairment (OR 1.17, 95% confidence interval (CI) 1.05-1.30) in men, but not in women. In women, sleep disturbance score (OR 2.62, 95% CI 1.41-4.86) and long sleep duration (≥ 9 hr; OR 3.70, 95% CI 1.49-9.17) were associated with nonamnestic and amnestic incident cognitive impairment, respectively. In men, short sleep duration (≤ 5 hr; OR 4.95, 95% CI 1.72-14.27) and habitual sleep efficiency score (OR 1.94, 95% CI 1.42-2.66) were associated with amnestic and general incident cognitive impairment, respectively. CONCLUSIONS: Sleep quality in older adults should receive particular attention by clinicians because poor sleep quality can be an early sign of cognitive decline.

OBJECTIVE: Given that aging is associated with higher risk of cognitive decline and dementia, improving early detection of cognitive impairment has become a research and clinical priority. The Montreal Cognitive Assessment (MoCA) is a screening instrument used to assess different aspects of cognition. Despite its widespread use, norms adjusted to the sociodemographics of Quebec-French people are not yet available. Such norms are however important because performance on neuropsychological tests varies according to sociodemographic variables including age, sex, and education. As such, the present study aimed to establish normative data for the MoCA in middle-aged and elderly Quebec-French population. METHOD: For that purpose, 1,019 community-dwelling older adults aged between 41 and 98 were recruited. Participants from 12 recruiting sites completed the MoCA. Regression-based normative data were produced and cross-validated with a validation sample (n = 200). RESULTS: Regression analyses indicated that older age, lower education level, and male sex were associated with poorer MoCA scores. The best predictive model included age (p < .001), education (p < .001), sex (p < .001), and a quadratic term for education (education X education; p < .001). This model explained a significant amount of variance of the MoCA score (p < .001, R2 = 0.26). A regression equation to calculate Z scores is presented. CONCLUSIONS: This study provides normative data for the MoCA test in the middle-aged and elderly French-Quebec people. These data will facilitate more accurate detection and follow-up of the risk of cognitive impairment in this population, taking into account culture, age, education, and sex.

This cross-sectional study proposes two relative strength indexes in order to evaluate the risks of lower mobility in healthy older adults: 1) handgrip strength on body mass index and 2) quadriceps strength on body weight. Nine hundred and four men and women aged between 67-84 years old were tested for body composition, muscle strength and mobility function. Individuals in the lowest and middle tertiles of relative handgrip strength were respectively 2.2 (1.3-3.7) and 4.4 (2.6-7.6) more likely to have a lower mobility score. As for relative quadriceps strength, odd ratios for lowest and middle tertiles were respectively 2.8 (1.6-4.9) and 6.9 (3.9-12.1). Relative strength indexes, either using handgrip strength or quadriceps strength, are convenient to use in large scale studies and clinical practice.

Many prospective studies have shown that a diet enriched in omega-3 polyunsaturated fatty acids (n-3 PUFAs) can improve cognitive function during normal aging and prevent the development of neurocognitive diseases. However, researchers have not elucidated how n-3 PUFAs are transferred from the blood to the brain or how they relate to cognitive scores. Transport into and out of the central nervous system depends on two main sets of barriers: the blood-brain barrier (BBB) between peripheral blood and brain tissue and the blood-cerebrospinal fluid (CSF) barrier (BCSFB) between the blood and the CSF. In this review, the current knowledge of how lipids cross these barriers to reach the CNS is presented and discussed. Implications of these processes in health and disease, particularly during aging and neurodegenerative diseases, are also addressed. An assessment provided here is that the current knowledge of how lipids cross these barriers in humans is limited, which hence potentially restrains our capacity to intervene in and prevent neurodegenerative diseases.

BACKGROUND: Poor food intake is common in acute care patients and can exacerbate or develop into malnutrition, influencing both recovery and outcome. Yet, research on barriers and how they can be alleviated is lacking. The present study aimed to (i) describe the prevalence of food intake barriers in diverse hospitals and (ii) determine whether patient, care or hospital characteristics are associated with the experience of these barriers. METHODS: Patients (n = 890; 87%) completed a validated questionnaire on barriers to food intake, including perceptions of food quality, just before their discharge from a medical or surgical unit in each of 18 hospitals across Canada. Scores were created for barrier domains. Associations between these barriers and selected patient characteristics collected at admission or throughout the hospital stay and site characteristics were determined using bivariate analyses. RESULTS: Common barriers were being interrupted at meals (41.8%), not being given food when a meal was missed (69.2%), not wanting ordered food (58%), loss of appetite (63.9%) and feeling too sick (42.7%) or tired (41.1%) to eat. Younger patients were more likely (P < 0.0001) to report being disturbed at meals (44.6%) than older patients (33.9%) and missing a meal for tests (39.0% versus 31.0%, P < 0.05). Patients who were malnourished, women, those with more comorbidity, and those who ate <50% of the meal reported several barriers across domains. CONCLUSIONS: The present study confirms that barriers to food intake are common in acute care hospitals. This analysis also identifies that specific patient subgroups are more likely to experience food intake barriers. Because self-reported low food intake in hospital was associated with several barriers, it is relevant to consider assessing, intervening and monitoring barriers to food intake during the hospital stay.

BACKGROUND: To date, the limited degrees of freedom (DOF) of most robotic training devices hinders them from providing functional training following stroke. We developed a 6-DOF exoskeleton ("BONES") that allows movement of the upper limb to assist in rehabilitation. The objectives of this pilot study were to evaluate the impact of training with BONES on function of the affected upper limb, and to assess whether multijoint functional robotic training would translate into greater gains in arm function than single joint robotic training also conducted with BONES. METHODS: Twenty subjects with mild to moderate chronic stroke participated in this crossover study. Each subject experienced multijoint functional training and single joint training three sessions per week, for four weeks, with the order of presentation randomized. The primary outcome measure was the change in Box and Block Test (BBT). The secondary outcome measures were the changes in Fugl-Meyer Arm Motor Scale (FMA), Wolf Motor Function Test (WMFT), Motor Activity Log (MAL), and quantitative measures of strength and speed of reaching. These measures were assessed at baseline, after each training period, and at a 3-month follow-up evaluation session. RESULTS: Training with the robotic exoskeleton resulted in significant improvements in the BBT, FMA, WMFT, MAL, shoulder and elbow strength, and reaching speed (p < 0.05); these improvements were sustained at the 3 month follow-up. When comparing the effect of type of training on the gains obtained, no significant difference was noted between multijoint functional and single joint robotic training programs. However, for the BBT, WMFT and MAL, inequality of carryover effects were noted; subsequent analysis on the change in score between the baseline and first period of training again revealed no difference in the gains obtained between the types of training. CONCLUSIONS: Training with the 6 DOF arm exoskeleton improved motor function after chronic stroke, challenging the idea that robotic therapy is only useful for impairment reduction. The pilot results presented here also suggest that multijoint functional robotic training is not decisively superior to single joint robotic training. This challenges the idea that functionally-oriented games during training is a key element for improving behavioral outcomes. TRIAL REGISTRATION: NCT01050231.

The aim of this study was to investigate the effect of HDL oxidation on PON1 paraoxonase activity. Also, we were interested in investigating the mechanism by which PON1 could be inactivated and the correlation between its enzymatic activity and the antioxidant properties of HDL. Three different oxidation systems were used for the HDL oxidation: (1) oxidation induced by THP1 cells, (2) oxidation induced by copper ions at a concentration 10 microM, and (3) oxidation induced by *OH and O2.- oxygen free radicals produced by gamma-radiolysis. HDL oxidation was followed by the measurement of lipid peroxide formation, and PON1 activity was determined by measuring the rate of paraoxon hydrolysis. Our results show that HDL oxidation is accompanied by a reduction in the PON1 paraoxonase activity. The extent of PON1 inactivation depends both on the extent of HDL oxidation and on the oxidation system used. The rates of HDL oxidation and PON1 inactivation were significantly correlated (r = 0.93, p < 0.0054). Our results show that oxidized HDL loses its protective effect toward LDL oxidation. The antioxidant action of HDL towards LDL oxidation and the degradation of PON1 paraoxonase activity were significantly correlated (r = 0.95, p < 0.04).

BACKGROUND: People suffering from dementia are particularly vulnerable to the gaps between the health and social service systems. Case management is a professional field that seeks to fill in these gaps and remedy this fragmentation. METHODS: We report the results of a systematic literature review of the impact of case management programs on clinical outcomes and the utilization of resources by persons with dementia. We focused on randomized controlled trials (RCTs) and attempted to identify the factors that might contribute to greater program efficacy. Because the evaluation methods in these studies varied, we used the effect size method to estimate the magnitude of the statistically significant effects reported. RESULTS: Our search strategy identified 17 references relating to six RCTs. Four of these six RCTs reported moderately statistically significant effects (effect size, 0.2-0.8) on their primary end point: the clinical outcome in three and resource utilization in one. Two of the RCTs reported weak or no effects (effect size, <0.2) on their primary end point. Because of the wide variety of the end points used, an overall effect size could not be calculated. Parameters that appear to be related to greater case management efficacy are the integration level between the health and social service organizations and the intensity of the case management. CONCLUSIONS: Integration and case management intensity seem to determine the magnitude of the clinical effects in this new professional field. Further studies are needed to clarify the economic impact.

Importance: Electronic cigarettes (e-cigarettes) for smoking cessation remain controversial. Objective: To evaluate e-cigarettes with individual counseling for smoking cessation. Design, Setting, and Participants: A randomized clinical trial enrolled adults motivated to quit smoking from November 2016 to September 2019 at 17 Canadian sites (801 individuals screened; 274 ineligible and 151 declined). Manufacturing delays resulted in early termination (376/486 participants, 77% of target). Outcomes through 24 weeks (March 2020) are reported. Interventions: Randomization to nicotine e-cigarettes (n = 128), nonnicotine e-cigarettes (n = 127), or no e-cigarettes (n = 121) for 12 weeks. All groups received individual counseling. Main Outcomes and Measures: The primary end point was point prevalence abstinence (7-day recall, biochemically validated using expired carbon monoxide) at 12 weeks, changed from 52 weeks following early termination. Participants missing data were assumed to be smoking. The 7 secondary end points, examined at multiple follow-ups, were point prevalence abstinence at other follow-ups, continuous abstinence, daily cigarette consumption change, serious adverse events, adverse events, dropouts due to adverse effects, and treatment adherence. Results: Among 376 randomized participants (mean age, 52 years; 178 women [47%]), 299 (80%) and 278 (74%) self-reported smoking status at 12 and 24 weeks, respectively. Point prevalence abstinence was significantly greater for nicotine e-cigarettes plus counseling vs counseling alone at 12 weeks (21.9% vs 9.1%; risk difference [RD], 12.8 [95% CI, 4.0 to 21.6]) but not 24 weeks (17.2% vs 9.9%; RD, 7.3 [95% CI, -1.2 to 15.7]). Point prevalence abstinence for nonnicotine e-cigarettes plus counseling was not significantly different from counseling alone at 12 weeks (17.3% vs 9.1%; RD, 8.2 [95% CI, -0.1 to 16.6]), but was significantly greater at 24 weeks (20.5% vs 9.9%; RD, 10.6 [95% CI, 1.8 to 19.4]). Adverse events were common (nicotine e-cigarette with counseling: 120 [94%]; nonnicotine e-cigarette with counseling: 118 [93%]; counseling only: 88 [73%]), with the most common being cough (64%) and dry mouth (53%). Conclusions and Relevance: Among adults motivated to quit smoking, nicotine e-cigarettes plus counseling vs counseling alone significantly increased point prevalence abstinence at 12 weeks. However, the difference was no longer significant at 24 weeks, and trial interpretation is limited by early termination and inconsistent findings for nicotine and nonnicotine e-cigarettes, suggesting further research is needed. Trial Registration: ClinicalTrials.gov Identifier: NCT02417467.

In Brief Objective: To investigate the specific impact of resistance training (RT) with or without caloric restriction (CR) on physical capacity in obese older women. Design: Forty-eight postmenopausal obese women, physically independent and between the ages of 55 and 75 years were recruited. The women were randomly assigned to one of four groups (1: RT [n = 12], 2: CR [n = 12], 3: CR + RT [n = 12], or 4: control group [C; n = 12]) for 3 months. CR and CR + RT groups participated in a weekly group session on nutrition, and RT and CR + RT groups took part in a resistance training program. Physical capacity was measured with 11 different performance tests. A global physical capacity score (range, 0-44) was then computed using quartiles of each test. Body composition was measured by dual-energy x-ray absorptiometry. Results: Body weight, total fat mass, percentage of fat mass, and body mass index (kg/m2) significantly decreased in the CR and CR + RT groups (P < 0.01), whereas only the CR group showed a significant decrease in lean body mass (P < 0.05) after the 3-month program. The global physical capacity score significantly improved in the RT group (10.0 ± 8.8%; P < 0.01), compared with the C group after 3 months. Conclusion: Overall, the 3-month RT program alone had a greater effect on physical capacity than CR or CR + RT. Thus, a 3-month RT could help prevent long-term decreases in physical capacity in obese older women. Resistance training had greater effects on physical capacity than caloric restriction alone or in combination with resistance training. Resistance training without weight loss could be a simple and effective approach to prevent long-term decreases in physical capacity in older obese women.

Benefits on cognition from docosahexaenoic acid (DHA, 22 : 6 n-3) intake are absent in humans carrying apolipoprotein E ε4 allele (APOE4), the most important genetic risk factor for Alzheimer's disease (AD). To test the hypothesis that carrying APOE4 impairs DHA distribution, we evaluated plasma and brain fatty acid profiles and uptake of [(14) C]-DHA using in situ cerebral perfusion through the blood-brain barrier in 4- and 13-month-old male and female APOE-targeted replacement mice (APOE2, APOE3, and APOE4), fed with a DHA-depleted diet. Cortical and plasma DHA were 9% lower and 34% higher in APOE4 compared to APOE2 mice, respectively. Brain uptake of [(14) C]-DHA was 24% lower in APOE4 versus APOE2 mice. A significant relationship was established between DHA and apoE concentrations in the cortex of mice (r(2) = 0.21) and AD patients (r(2) = 0.32). Altogether, our results suggest that lower brain uptake of DHA in APOE4 than in APOE2 mice may limit the accumulation of DHA in cerebral tissues. These data provide a mechanistic explanation for the lack of benefit of DHA in APOE4 carriers on cognitive function and the risk of AD. Using human APOE2, 3, and 4 isoform-specific transgenic mice, we found a lower brain uptake of docosahexaenoic acid (DHA) in APOE4 than in APOE2 mice that may limit the biodistribution of DHA in cerebral tissues. These data provide a mechanistic explanation for the lack of benefit of DHA in APOE4 carriers on cognitive function and the risk of Alzheimer's disease (AD).

PURPOSE: Few standardized outcome measures used in the clinical assessment of wheelchair user performance assess or document all the factors that influence mobility. This article presents a conceptual framework that suggests a more all-encompassing view of wheelchair mobility performance assessment. METHOD: After determining, through a survey of the literature, which factors influence wheelchair mobility, a conceptual framework was proposed. Outcome measures of wheelchair mobility were then surveyed. An analysis of these assessment tools allowed factors to be determined that were considered in the clinical assessment of wheelchair mobility performance. A comparison of these led to observations being drawn, which could allow the development of a valid and reliable standardized outcome measure to be used in clinics. RESULTS AND CONCLUSION: Future improvements to the clinical assessment of wheelchair mobility performance should focus on developing an assessment tool considering all categories of factors influencing wheelchair mobility. These categories are the user's profile, the wheelchair, the environment, the daily activities and social roles and the assessment and training received. A controlled-environment outcome measure using a standardized obstacle course with fundamental situations would allow rehabilitation therapists to evaluate clients for the selection of a wheelchair and to document their progress during training. This tool should make it possible to extrapolate the results and thereby apply them to daily activities and social roles.

UNLABELLED: Judicious food choices are of prime importance during aging. OBJECTIVES: This study was conducted to identify individual and collective attributes determining global diet quality (DQ). METHODOLOGY: Participants were 1,793 adults (52% women) from the NuAge study on nutrition and successful aging. Subjects aged 67 to 84 years in relatively good health were recruited from the Québec Medicare Database. Sociodemographic, affective, and cognitive data, health conditions, perceived physical health and functional status, dietary habits and dietary attributes and community resources were obtained using questionnaires. Body weight and height were measured and body mass index (BMI) was calculated. Three non-consecutive 24-hour diet recalls were collected at recruitment. DQ, assessed using the Canadian Healthy Eating Index (C-HEI, /100), was computed on the mean intakes from the diet recalls. Analyses were stratified by gender. Variables significantly related to DQ in bivariate analyses (p<.05) were entered into backward stepwise multiple regression analyses. RESULTS: Among men, the final model showed higher education (β=0.23, p=.01), diet knowledge (β=0.96, p<.0001), number of daily meals (β=1.91, p=.02) and perceived physical health (β=0.06, p=.01) to be positive determinants of DQ, whereas alcohol consumption (β=-2.25, p=.05), wearing dentures (β=-2.31, p=.01) and eating regularly in restaurants (β=-1.65, p=.03) were negative determinants of DQ (adjusted R2 = 13.7%). Among women, higher education (β=0.29, p=.002), diet knowledge (β=0.54, p=.002), number of daily meals (β=3.61, p<.0001), and hunger (β=0.61, p<.0001) were positive determinants of global DQ; greater BMI (β=-0.16, p=.03) and chewing problems (β=-0.48, p=.03) were negative determinants of DQ (adjusted R2 = 7.8%). DISCUSSION: These results point to several key factors influencing global DQ in older adults and also show gender-based differences. More research must be done to better understand how these factors change with aging and exert their impact on diet, particularly since variance in DQ was largely unexplained. As diet knowledge was an independent predictor for both genders, targeted, sustainable interventions are needed to ensure good diet quality as people age.

Wearable sensors such as inertial measurement units (IMUs) have been widely used to measure the quantity of physical activities during daily living in healthy and people with movement disorders through activity classification. These sensors have the potential to provide valuable information to evaluate the quality of the movement during the activities of daily living (ADL), such as walking, sitting down, and standing up, which could help clinicians to monitor rehabilitation and pharmaceutical interventions. However, high accuracy in the detection and segmentation of these activities is necessary for proper evaluation of the quality of the performance within a given segment. This paper presents algorithms to process IMU data, to detect and segment unstructured ADL in people with Parkinson's disease (PD) in simulated free-living environment. The proposed method enabled the detection of 1610 events of ADL performed by nine community dwelling older adults with PD under simulated free-living environment with 90% accuracy (sensitivity = 90.8%, specificity = 97.8%) while segmenting these activities within 350 ms of the "gold-standard" manual segmentation. These results demonstrate the robustness of the proposed method to eventually be used to automatically detect and segment ADL in free-living environment in people with PD. This could potentially lead to a more expeditious evaluation of the quality of the movement and administration of proper corrective care for patients who are under physical rehabilitation and pharmaceutical intervention for movement disorders.

This study assessed test-retest reliability and relative validity of the Short Diet Questionnaire (SDQ) and usability of an online 24 h recall among 232 participants (62 years ± 9.1; 49.6% female) from the Canadian Longitudinal Study on Aging (CLSA). Participants were asked to complete four 24 h dietary recalls (24HRs) using the Automated Self-Administered 24-h Dietary Assessment Tool (ASA24-Canada-2014), two SDQ administrations (prior to recalls one and four), and the System Usability Scale (SUS) for ASA24. For the SDQ administrations, Intraclass Correlation Coefficients ranged from 0.49 to 0.57 for nutrients and 0.35 to 0.72 for food groups. Mean intakes estimated from the SDQ were lower compared than those from the 24HRs. For nutrients, correlation coefficients were highest for fiber, calcium, and vitamin D (45–64 years: 0.59, 0.50, 0.51; >65 years: 0.29, 0.38, 0.49, p < 0.01); Kappas ranged from 0.14 to 0.37 in those 45–64 years and 0.17 to 0.32 in participants >65 years. Among the 70% who completed all recalls independently, the SUS indicated poor usability, though the majority reported feeling confident using ASA24. Overall, the SDQ captures intake with varying test-retest reliability and accuracy by nutrient and age. Further research is needed to inform use of a more comprehensive dietary measure in the CLSA.

Semantic memory tests assess long-term memory for facts, objects, and concepts as well as words and their meaning. Since it holds culturally shared information, the development of normative data adjusted to the cultural and linguistic reality of the target population is of particular importance. The present study aimed to establish normative data for the Pyramids and Palm Trees Test, a commonly used test of semantic memory, in the French-Quebec population. The normative sample consisted of 214 healthy French-speaking adults and elderly persons from various regions of the province of Quebec. The effects of participants' age, gender, and education level on test performance were assessed. Results indicated that participants' level of education and age, but not sex, were found to be significantly associated with performance on this test. Normative data are presented as means and standard deviations. Overall, the present norms are consistent with those of previous studies with Spanish samples.

OBJECTIVE: This paper examined whether or not closer proximity to local services and amenities was associated with maintenance of more frequent walking over time among urban-dwelling seniors over and above individual-level characteristics. METHOD: A sample of 521 adults who were part of the VoisiNuAge study and who resided in a large North American urban area reported on the frequency of walking outside the home over a 3-year period and on their health, sociodemographic characteristics, social support and resources, and perceptions of different features of their residential environment. Information about the distance between their home and 16 services and amenities was obtained from a geographic information system. Seniors were then classified into quartiles of proximity (Q1, Q2, Q3, Q4). RESULTS: Unadjusted and adjusted ordinal growth curve models showed that closer proximity to services and amenities was associated with greater likelihood of frequent walking at all times throughout the 3-year period. DISCUSSION: Findings are consistent with the notion that environments may act as buoys for the maintenance of important health behaviors. Future experimental and quasi-experimental research is required to explore whether or not the environment can play a causal role in influencing patterns of walking over time.