THE COMBINED EFFECTS OF SOCIAL ISOLATION AND LONELINESS ON PSYCHOLOGICAL WELL-BEING DURING THE COVID-19 PANDEMIC

Abstract Social isolation and loneliness are related but distinct constructs. A number of studies have examined these two constructs separately; however, the combined and interactive effects of social isolation and loneliness on health outcomes have rarely been studied. Using the most recent data of the Health and Retirement Study (HRS 2020) collected during the pandemic, this study aimed to explore the latent classes of social isolation and loneliness among adults aged 60 and older (N=3,486) and to examine the associated psychological well-being. Social isolation was measured by five indicators, including living alone, no membership in any organizations, and less than once a month contact with children, relatives, and friends. Loneliness was measured by the 3-item UCLA scale. Four classes were identified by the Latent Class Analysis (LCA): neither isolated nor lonely (class 1, 35%), living alone and lonely (class 2, 25%), no social participation and lonely (class 3, 18%), and highly isolated and lonely (class 4, 23%). The results of multivariate regression indicated that compared to respondents who were neither isolated nor lonely, those who were in the class of living alone and lonely and the class of highly isolated and lonely had more depressive symptoms, stress, anxiety, worry, loneliness during the pandemic. The latent class of no social participation and lonely was associated with more depressive symptoms and covid-related stress. This study emphasizes the importance of specialized intervention strategies targeting the unique needs of older adults with different experiences of social isolation and loneliness.

Background: The lockdown due to COVID-19 has influenced individuals' lives in many aspects. Yet, the impact of reopening under an ongoing pandemic is understudied. This study aims to investigate the impact of reopening policy on older Asian Americans' depressive symptoms and whether the impact varies by their sociodemographic characteristics.Method: We used interview data collected from 519 Chinese and Korean aged 60 and older in New York City between 5/23/2021 to 7/30/2021. Interrupted time series model was used to test whether there are significant level and slope changes in depressive symptoms (PHQ-9 scale) before and after the reopening on 7/1/2021 in NYC. We then ran the models in stratified sample by gender, education, income, self-reported health, and social connectedness through living arrangements, use of technology, and social interactions.
Results: Older Asians' depression increased immediately following the reopening (ß=1.52, p< 0.05), and then slowly decreased then after (ß=-0.12, p< 0.001). A decrease in depression following reopening was significantly associated with the male gender, good health, higher income, living alone, having received or provided social support, daily texting, and no engagement in the discussions related to COVID-19 in social media. Discussions: While reopening may have long-term benefits on mental health, older Asians were anxious about their safety at the beginning of reopening under an ongoing pandemic. Older adults with worse health, lower SES, and limited social connectedness struggled to adjust to "back-to-normal" life. We discussed research, policy, and practice implications to support these disadvantaged older adults after reopening.

THE COMBINED EFFECTS OF SOCIAL ISOLATION AND LONELINESS ON PSYCHOLOGICAL WELL-BEING DURING THE COVID-19 PANDEMIC
Ke Li, and Fengyan Tang, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Social isolation and loneliness are related but distinct constructs. A number of studies have examined these two constructs separately; however, the combined and interactive effects of social isolation and loneliness on health outcomes have rarely been studied. Using the most recent data of the Health and Retirement Study (HRS 2020) collected during the pandemic, this study aimed to explore the latent classes of social isolation and loneliness among adults aged 60 and older (N=3,486) and to examine the associated psychological well-being. Social isolation was measured by five indicators, including living alone, no membership in any organizations, and less than once a month contact with children, relatives, and friends. Loneliness was measured by the 3-item UCLA scale. Four classes were identified by the Latent Class Analysis (LCA): neither isolated nor lonely (class 1, 35%), living alone and lonely (class 2, 25%), no social participation and lonely (class 3, 18%), and highly isolated and lonely (class 4, 23%). The results of multivariate regression indicated that compared to respondents who were neither isolated nor lonely, those who were in the class of living alone and lonely and the class of highly isolated and lonely had more depressive symptoms, stress, anxiety, worry, loneliness during the pandemic. The latent class of no social participation and lonely was associated with more depressive symptoms and covid-related stress. This study emphasizes the importance of specialized intervention strategies targeting the unique needs of older adults with different experiences of social isolation and loneliness.

AGING-RELATED ADIPOSE REMODELING AND DYSFUNCTION
Chair: Qiong (Annabel) Wang Aging is associated with insulin resistance, cardiovascular dysfunction, and many other chronic metabolic disorders, significantly shortening healthspan and lifespan. Fat (adipose) tissue, as the major site for energy storage, maintains whole-body energy homeostasis and insulin sensitivity. Adipose tissue has extraordinary plasticity, and it was not until recently that fat tissue remodeling during aging is considered to play an essential role in aging-associated metabolic disorders. Benefiting from recent technology advances, especially the single-cell technology and comprehensive genetic mouse models, we are beginning to unmask how adipose tissue remodels during aging cellularly and molecularly. This symposium features internationally-renowned aging research scientists whose work focuses on how aging remodels adipose tissues and how adipose tissue is vital for healthy aging and longevity. We will hear from Philipp Scherer from The University of Texas Southwestern Medical Center, who will present his research on the impact of adipocyte-derived factors on Healthspan and Lifespan; Hei Sook SUL from the University of California Berkeley will discuss "Aging dependent changes in adipose precursors"; Annabel Wang from the City of Hope will introduce her recent discovery of a new type of adipocyte progenitor cell that promotes aging-related visceral adiposity; and lastly, Gina Wade from the University of Wisconsin-Madison who will talk about "Regulation of aging energy expenditure by plasma lipid signaling". Attendees will learn about the latest breakthroughs in adipose tissue aging, and the role of adipose tissue in maintaining and restoring metabolic health in aged individuals.

A UNIQUE ADIPOCYTE PROGENITOR POPULATION PROMOTES AGE-RELATED ADIPOSITY Qiong (Annabel) Wang, City of Hope, City of Hope, California, United States
The average fat mass in adults increases dramatically with age, and older people often suffer from visceral obesity and related adverse metabolic disorders. Unfortunately, how aging leads to fat accumulation is poorly understood. It is known that fat cell (adipocyte) turnover is very low in young mice, similar to that in young humans. Here, we find that mice mimic age-related fat expansion in humans. In vivo lineage tracing shows that massive adipogenesis (the generation of new adipocytes), especially in the visceral fat, is triggered during aging. Thus, in contrast to most types of adult stem cells that exhibit a reduced ability to proliferate and differentiate, the adipogenic potential of adipocyte progenitor cells (APCs) is unlocked by aging. In vivo transplantation and 3D imaging of transplants show that APCs in aged mice cell-autonomously gain high adipogenic capacity. Single-cell RNA sequencing analyses reveal that aging globally remodels APCs. Herein, we identify a novel committed preadipocyte population that is age-specific (CP-A), existing both in mice and humans, with a global activation of proliferation and adipogenesis pathways. CP-A cells display high proliferation and adipogenesis activity, both in vivo and in vitro. LIFR serves as a functional maker of CP-A, which promotes CP-A proliferation. Together, these findings define a new fundamental mechanism involved in fat tissue aging and offer prospects for preventing and treating age-related metabolic disorders.

ADIPOCYTE-DERIVED FACTORS: IMPACT ON HEALTHSPAN AND LIFESPAN Philipp Scherer, The University of Texas Southwestern Medical Center, Dallas, Dallas, Texas, United States
Adipocytes secrete numerous lipid and protein factors with profound effects on systemic energy homeostasis. One such adipokine that we first identified in the early 1990's, adiponectin, has garnered significant attention as a potent mediator of insulin sensitivity and cell survival. FGF21 is another factor that is secreted by a number of cell types (including adipocytes), which has a beneficial effect on metabolism. Our group generated a novel mouse model that overexpresses, in an inducible fashion, physiological levels of FGF21 from adipocytes in the adult mouse. While comparable levels of constitutive overexpression of FGF21 from the liver do not have an impact on aging, adipocyte-derived FGF21 exerts a profound beneficial impact on health-and lifespan. This demonstrates that selective manipulation of adipose tissue per se has the potential to significantly reduce mortality and extend lifespan. The adipocyte-specific FGF21 transgenic animals have increased energy expenditure, weigh considerably less and exhibit an improvement in all systemic metabolic parameters examined to date. The mice further display unique immunemetabolic profiles of their adipose tissue depots, which defy the conventional changes associated with aging. Importantly, all these phenotypic alterations are achieved without a significant impact on adipose tissue beiging/browning. Moreover, at least some beneficial aspects of FGF21 appear to be mediated through a lowering of leptin, which leads to central leptin sensitization. Combined, these efforts shed additional light on the physiological effects of FGF21.

AGING-DEPENDENT CHANGES IN ADIPOSE PRECURSORS Hei Sook Sul, and Frances Lin, University of California, Berkeley, Berkeley, California, United States
Adipose tissue mass and adiposity change throughout the lifespan. During aging, while visceral adipose tissue (VAT) tends to increase, peripheral subcutaneous adipose tissue (SAT) decreases significantly. Unlike VAT, which is linked to metabolic diseases, including type 2 diabetes, SAT has beneficial effects. However, the molecular details behind the aging-associated loss of SAT remain unclear. Here, by comparing scRNA-seq of total stromal vascular cells of SAT from young and aging mice, we identify an aging-dependent regulatory cell (ARC) population that emerges only in SAT of aged mice and humans. ARCs express adipose progenitor markers but lack adipogenic capacity; they secrete high levels