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In recent years, there has been increased public and research attention directed towards the international “epidemic of loneliness” among older adults, as well as in the broader general population. Overall prevalence varies somewhat by method of assessment and country or region of sampling, but the bulk of studies suggest a general prevalence of approximately 20%–25%. The relationship of aging to the risk and nature of loneliness is complex, with inconsistent findings across studies, and may be affected by a number of specific factors, such as age-related loss of spouse/partners, changes in one’s broader social network, other environmental changes, as well as a range of positive and negative psychological factors. In older and younger adults, loneliness is not only an aversive experience, it has a deleterious impact on cognitive and physical health, and is associated with a substantial increase in all-cause mortality (Cacioppo et al., 2015). Of the multiple adverse effects of loneliness on health and well-being, one of those most relevant to the maintenance of independent functioning among older adults is the increased risk of cognitive dysfunction and dementia (Cacioppo et al., 2015). Elucidation of the mechanisms underlying these associations is needed to develop better prevention and intervention strategies. One relevant component in that effort is clarifying the nature, evolution, and effects of objective social isolation in combination with loneliness. Prior research has shown that social isolation and loneliness each affect cognitive functioning, health, and mortality, but the two constructs are not synonymous. “Social isolation” refers to deficits in a person’s objective social network and support. In contrast, loneliness represents a subjective internal state resulting from a selfperceived discrepancy between one’s actual social relationships versus one’s desired social relationships. Social isolation can lead to loneliness, and persistent loneliness can exacerbate objective social isolation, but the two constructs are only modestly correlated (r∼ 0.25–0.28). The distinction is in itself seemly self-evident as a true introvert may be very isolated but feel no loneliness, while an extrovert may still feel “alone in the crowd.” Although exploratory in nature, the report from Fung et al. (2018) nicely illustrates an approach toward elucidating the potential interactive effects of loneliness and social isolation on cognitive functioning. They employed a cross-sectional design, using in-person interviews with 497 “cognitively healthy” older adults (ages ≥ 60 years) residing in HongKong.Akey aspect of their studywas that social network size was measured in reference to two dimensions: (1) “confiding” versus “non-confiding” network, and (2) “close-ties” (i.e., number of family) versus “non-close” ties (i.e., number of friends). Confiding versus non-confiding network sizes were defined as the numbers of persons whom the respondents felt they could share versus couldnot share their inner feelings. The focus of analyses was on the interaction of overall loneliness (total score on the Chinese version of the de Jong Gierveld Loneliness Scale) with the above dimensions of social network size, as statistical predictors of the concurrent level of cognitive functioning (a composite of delayed recall from a word list, category fluency, and total score on the Chinese version of the Mini-Mental State Examination). After controlling for various potential confounding factors, they found a significant interaction of loneliness and non-confiding network size in the statistical prediction of concurrent cognitive composite scores. In contrast, there were no significant interactions of loneliness and confiding network size, or total network size, as statistical predictors of cognitive functioning. Further post-hoc analyses suggested that the interaction effects of non-confiding network size were present only for the number of close-ties (i.e., number of family members), not for number of friends in the non-confiding network. The exploratory nature of Fung et al.’s study makes definitive conclusions difficult. There is no clear conceptual model that would have led to an a priori hypothesis predicting the above pattern of findings. Thus, the authors are appropriately very cautious in terms of avoiding definitive interpretation of their results. However, the investigators suggest that the findings raise the possibility that interventions focused on expanding social network size may be ineffective in countering the deleterious effects of loneliness. They also noted that “while our results only served to provide a legitimate basis for hypothesis generation, it remains interesting to explore if the unsatisfactory feeling of loneliness would come from International Psychogeriatrics (2019), 31:4, 447–449 © International Psychogeriatric Association 2019