Profiling obesity phenotypes and trajectories in older adults of the Quebec NuAge cohort on nutrition and successful aging: A cluster analysis.

Obesity in older adults results from several interacting factors. Consequently, interventions have shown mitigated effects. We determined (a) the different subgroups of older adults with obesity based on clusters of associated comorbidities and (b) the trajectory of these clusters to assess their stability over 3 years and factors contributing to transitions. Obese men (n = 193; body mass index [BMI] = 33.15 ± 2.69 kg/m2 ) and women (n = 220; BMI = 33.71 ± 3.71 kg/m2 ) aged between 68 and 82 years were studied. Outcome variables were body composition, strength, physical capacity (PC), nutrition, psychological and physical health and social participation. Cluster analyses, stratified by sex, were used to identify obesity profiles at baseline and follow-up. Three profiles were identified, based on general health (GH), psychological health (PH) and PC: Cluster 1: healthy obese (GH+, PH+, PC+); Cluster 2: obese with low PC (GH+/-, PH+/-, PC-); Cluster 3: unhealthy obese (GH-, PH-, PC-). After 3 years, 61.2% and 70.2% of men and women remained in their initial cluster, compared to 20.4% and 13.7% who transitioned towards a worse health cluster and 18.3% and 16.0% who transitioned towards a more favourable cluster, partly explained by changes in physical health for men and physical health and PH for women. The results of this study show that targeting physical function in men and physical health and PH functions in women could prevent further health decline in older adults with obesity. Further studies are needed to investigate the role of these clusters in the prediction of cardiometabolic complications and mortality.

Letter to the Editor: RE: Costa et al. (''Nutritional Risk is Associated with Chronic Musculoskeletal Pain in Community-Dwelling Older Persons: The PAINEL Study'').

We read Costa and colleagues' report1 in 2016 in the Journal of Nutrition in Gerontology and Geriatrics with great interest. In this article, the authors reported a statistically significant association between chronic musculoskeletal pain and nutritional risk after controlling for age, gender, body mass index (BMI), depression (GDS, geriatric depression scale), and diabetes in a Brazilian community-dwelling older adult's population (the PAINEL study, see Table 2 in Costa et al. 1 . However, in their study, Costa and colleagues used the DETERMINE 2 Questionnaire, a questionnaire in which 3 out of the 10 questions are directly or indirectly related to pain (i.e., presence of an illness, tooth or mouth problems, and physical disability). The purpose of this letter is to discuss the potential drawbacks of including pain-related questions in nutrition risk screening tool when these tools are used to investigate the relationship between pain and nutritional risk.

Association Between Anticholinergic Drug Use and Health-Related Quality of Life in Community-Dwelling Older Adults.

BACKGROUND: The use of drugs with anticholinergic properties (AC drugs) has been associated with decreased functioning and impaired cognition in older adults. Studies assessing the association between AC-drug use and health-related quality of life (HRQoL) show conflicting results. OBJECTIVE: The aim was to evaluate the association between AC-drug use and HRQoL in community-dwelling older adults. METHODS: The NuAge cohort study enrolled 1793 men and women aged 68-82 years. The participants were free of disabilities in activities of daily living, not cognitively impaired at recruitment and followed annually for 3 years (December 2003-May 2005). AC-drug exposure was assessed using the Anticholinergic Cognitive Burden Scale (ACBS). HRQoL was assessed using the physical (PCS) and mental (MCS) component summaries of the 36-item Short Form Survey (SF-36) questionnaire. The association between AC drug and HRQoL was determined by a mixed model analysis using four annual time points. RESULTS: At recruitment the mean age was 74.4 ± 4.2 years, 52% were female and 33% of participants were prescribed at least one AC drug. The mean PCS and MCS (/100) scores were 49.0 ± 8.2 and 54.9 ± 8.1, respectively. In the mixed model analysis, an increase of 1 on the ACBS was associated with a decrease of -0.50 (95% CI -0.68 to -0.31) in the PCS and an increase of 0.19 (95% CI 0.01-0.37) in the MCS. CONCLUSIONS: In a cohort of generally healthy community-dwelling older adults, AC-drug exposure was associated with a statistically significant decrease in the PCS and increase in the MCS throughout the entire follow-up period. However, the effects on the PCS and MCS were small and likely not clinically relevant.

A new approach for detecting and analyzing cutaneous reflexes during locomotion.

During human walking, due to their small amplitude, individual cutaneous reflex responses are difficult to detect in surface EMG recordings. In this study, we present a new algorithm to automatically detect individual cutaneous reflex responses and to extract their corresponding onset latency, amplitude, duration, and sign. To discriminate reflex responses from the intrinsic variability of the background EMG, each stimulated cycle is compared with 10 adjacent nonstimulated cycles, looking for consistent differences. In the first 200 ms after stimulation, reflex responses are detected when ≥ 9/10 of these differences are either positive or negative. This approach does not require amplitude thresholds or fixed time windows for reflex detection. To reduce false detections, a postprocessing step selects 50 nonstimulated cycles randomly, processes them through the algorithm as stimulated cycles, and establishes a minimal reflex duration criterion that it then used to validate the detected responses. Validated responses from an entire test session are then reported on a colormap (reflex activity map) from which specific responses can be identified and quantified. The new method was validated in ten participants, three cutaneous nerves, and two protocols (phase modulation and recruitment curves). Compared with the classical method, the new algorithm showed better performance in terms of detection accuracy, specificity, and reliability. Although tested here to evaluate cutaneous reflexes during human walking, the simplicity of this method is such that it could easily be used with other reflexes, signals, and preparations.

Estimating conductances of dual-recorded neurons within a network of coupled cells.

Simultaneous pre- and postsynaptic cell recordings are used to calculate gap junction conductance based on an equivalent electrical circuit of an electrically coupled pair of cells. This calculation is imprecise when recording from a cell pair that is coupled to neighboring cells providing indirect conductance paths between the recorded cells. Despite this imprecision, junctional conductance has been calculated for coupled cell networks during the past 40 years since a more accurate method was lacking. The present study simulated a three-dimensional network of electrically coupled heterogeneous neurons and used mathematical modeling to reduce the complexity to the simplest equations that could more accurately estimate the electrical properties of dual-recorded cells in the network. Analyses of the simulations showed that knowledge of the number of unrecorded cells directly linked to the recorded cells and of the voltage responses of these recorded cells were largely sufficient to accurately predict the direct junctional resistance linking the recorded cells as well as the input resistance of the recorded cells that would exist in the absence of junctional coupling. All model parameters could be obtained from real dual-intracellular penetrations which allow electrophysiological recordings and intracellular staining.