In 2023, the U.S. Surgeon General declared loneliness an epidemic, stating that its consequences extend far beyond “just a bad feeling” (HHS, 2023). While loneliness is typically recognized as an unpleasant emotional response to perceived isolation, it can also have impacts on cognitive, physical, and mental health.
Research shows that even before the COVID-19 pandemic left many people feeling isolated from their social support networks, 61% of Americans reported feeling lonely (Cigna, 2020). This makes loneliness—and closely related experiences of social isolation—a growing public health concern that can be felt across workplaces, schools, and society at large.
For patients seeking healthcare support for feelings of loneliness, primary care providers have a crucial role to play in connecting patients with mental health specialists, encouraging social interaction, and understanding the impact of social context on brain health (Lock et al., 2023). It's all part of a whole-person approach to health that looks beyond symptoms and takes into account social and environmental factors at play in a person's health.
But what exactly does it mean to be lonely? What happens when people are lonely for too long? What are the physical effects of loneliness? This article explores research on the connection between loneliness and brain health and shares how healthcare providers can help patients overcome chronic loneliness.
The Chronic Loneliness Epidemic
The terms “loneliness” and “social isolation” are often used interchangeably, but they differ in some fundamental ways. Loneliness refers to the subjective feeling of being alone or lacking meaningful social connections (Yanguas et al., 2018). Social isolation, however, describes the objective lack of social contact (Veazie et al., 2019).
Loneliness is also not the same as solitude. Some people may enjoy time alone, whether it's for brief or extended periods of time, and therefore don’t suffer the same negative health outcomes as those who feel lonely. Perceived loneliness—the degree to which someone feels that their social needs are not being met—is influenced by various social determinants of health, including socioeconomic status, access to healthcare, and environmental factors (CDC, 2024).
The U.S. and Canada have experienced a substantial rise in loneliness in recent years. In the U.S., rates of loneliness are notably high among young adults, people with lower incomes, and racial and ethnic minorities (Cigna, 2021). These findings are consistent in Canada, with approximately two thirds of 18 to 54-year-olds reporting that they feel a lack of belonging and 76% of unemployed people feeling cut off from their communities (YMCA, 2024).
The effects of social isolation can be significant. Research links chronic loneliness to an increased risk of depression, anxiety, and cognitive decline, including dementia (Guarnera et al., 2023). Loneliness can also trigger inflammatory responses in the body, impacting brain function and potentially accelerating age-related cognitive decline (Finley & Schaefer, 2023).
Healthcare providers play a vital role in addressing this public health crisis. By acknowledging the profound impact of social isolation—and conversely, social connection—on patient outcomes, they can advocate for lifestyle changes that promote social connectedness and reduce feelings of loneliness.
What Loneliness Does to the Brain
Loneliness can have a profound impact on mental, cognitive, and physical health. From anxiety and depression to dementia to cardiovascular disease and stroke, loneliness is associated with increased risks of various health concerns (HHS, 2023). It can benefit both patients and healthcare providers to consider and discuss a patient's experience of loneliness as part of a whole-personal approach to care.
Effects on Mental Health
Loneliness is strongly associated with an increased risk of depression and anxiety (Erzen & Çikrikci, 2018; Wilkialis et al., 2021). Studies have shown that individuals experiencing chronic loneliness exhibit elevated levels of stress hormones, which can disrupt brain function and contribute to the development of mental health disorders (HHS, 2023).
Chronic loneliness can also lead to changes in brain structure and function, particularly in areas associated with emotional regulation and social cognition (Finley & Schaefer, 2023). These brain changes can make individuals more anxious, sensitive to social threats, more likely to negatively interpret social cues, and therefore less likely to seek out social connection—perpetuating a cycle of loneliness and mental health challenges. Additionally, loneliness can disrupt sleep patterns, leading to insomnia and daytime fatigue, which can further exacerbate negative mental health symptoms and cognitive impairment (Qi et al., 2023; Wild et al., 2018).
Effects on Cognitive Health
Just as concerning is the link between loneliness and cognitive decline. Research suggests that chronic loneliness can accelerate brain aging, increase the risk of dementia by roughly 40%, and impair cognitive functions including memory, attention, and executive function (Guarnera et al., 2023; Sutin et al., 2018). Other studies show that loneliness can increase the risk for Alzheimer’s Disease by 14%, vascular dementia by 17%, and cognitive impairment by 12% (NIH, 2025; Luchetti et al., 2024). This may be partially due to the neurobiological effects of chronic stress and inflammation, which can damage brain cells and disrupt neural pathways (Finley & Schaefer, 2023).
Loneliness can also lead to reduced engagement in cognitively stimulating activities, such as learning new skills or engaging in social interactions, which can further accelerate cognitive decline (Cardona, 2023). Studies have shown that loneliness is associated with a reduction in grey matter volume in certain brain regions, including the hippocampus, which plays a crucial role in memory, learning, and spatial navigation (Lammer et al., 2023). This suggests that promoting the development and maintenance of social networks can support a reduced risk of dementia.
Physical Effects of Loneliness
Loneliness has significant physical health consequences too, including an increased risk of cardiovascular disease, weakened immune function, and higher rates of chronic conditions such as diabetes and hypertension (Valtorta et al., 2016; Henriksen et al., 2022; Momtaz et al., 2012).
These physical health issues can also exacerbate cognitive decline and increase the risk of dementia. For instance, cardiovascular disease can lead to reduced blood flow to the brain, depriving brain cells of essential nutrients and oxygen, which can contribute to cognitive impairment and the development of dementia later in life (Cho et al., 2022). Some research has reported that the mortality impact of loneliness is equivalent to that caused by smoking up to 15 cigarettes a day (Holt-Lunstad et al., 2017; HHS, 2023).
Loneliness can also lead to changes in lifestyle behaviors, such as poor diet, lack of exercise, and increased substance use, which can contribute to physical health problems and cognitive decline (Livingston et al., 2024; Nichols et al., 2024). Additionally, loneliness can disrupt the body's stress response system, leading to chronic inflammation, which has been linked to a variety of age-related diseases including cardiovascular disease, cancer, and dementia (Finley & Schaefer, 2023).
Resources for Healthcare Providers
Healthcare providers have a powerful opportunity to effectively address the loneliness epidemic and reduce the negative health outcomes of loneliness. In a whole-person approach to care, healthcare providers evaluate the physical, mental, cognitive, social, economic, and environmental factors that impact each patient's health. These social determinants of health can particularly affect a person’s likelihood of feeling lonely and should be a primary focus when assessing loneliness and planning interventions (Lock et al., 2023).
Providers can begin to gather this information from patients by using a combination of subjective measures, such as questionnaires, screeners, and clinical interviews, as well as objective measures to monitor the impacts of loneliness on brain health.
Identifying Patients At Risk Of Loneliness
Screening for social isolation and loneliness during routine check-ups can help providers build a complete picture of patient well being. Providers can engage patients in conversations about their social connections and support systems by incorporating questions about loneliness into intake forms and annual wellness visits.
For example, healthcare professionals can ask, “How often do you feel lonely or isolated?” or “Do you feel like you have someone to rely on for support?”
Mental health questionnaires, such as the PSS for stress, PHQ-9 for depression, and GAD-7 for anxiety can also be used to screen patients for conditions associated with perceived loneliness and social isolation. Paired with cognitive health assessments, these practices support a whole person approach to health.
Connecting Patients with Community Resources
Lonely individuals may not know where to start to find opportunities for connection, so referring patients to social support groups, community centers, and other resources can help combat loneliness by lowering the barrier to social connection. By providing a comprehensive list of local organizations, social activities, and mental health services, care providers can actively connect patients with appropriate resources and promote community engagement.
Promoting Healthy Social Behaviors
Similarly, encouraging patients to engage in social activities, such as joining clubs, volunteering, or spending time with friends and family, can help mitigate the health risks of loneliness, particularly cognitive decline and dementia (Gardener et al., 2022). Social anxiety is one potential barrier to engaging in healthy social behaviors (Kashdan 2007; Goetter et al., 2020). Providers can address social anxiety by treating this condition directly or referring to appropriate mental health professionals.
Providers can offer support and guidance to patients who experience social anxiety by encouraging gradual exposure to social situations and providing tools for managing symptoms.
For patients with limited opportunities to attend in-person activities due to age, mobility, or location, providers can help by referring patients to classes or resources that provide assistance using technology to connect with others online through virtual social groups or mental health resources.
Addressing Social Inequities
Providers should be aware of factors that can increase the risk of loneliness, such as older age, living alone, recent loss of a loved one, chronic illness, disability, access to transportation and health services, and socioeconomic disadvantage (Smale et al., 2022).
Beyond what's possible in a patient appointment, advocacy and policy are key drivers in addressing the social determinants of health, and working to reduce disparities in access to healthcare and social support (Lock et al., 2023) . Local organizations, for example, work to develop programs and interventions that address the needs of marginalized populations and promote social inclusion for everyone. Educational organizations teach patients and the community about the impact of social isolation and loneliness on health, helping raise awareness about this important public health concern.
Measuring the Brain Health Impacts of Loneliness
Acknowledging the presence and seriousness of loneliness is only one part of the journey to course-correcting this epidemic. While traditional assessments of mental health are invaluable resources, they are only part of the picture of health. That’s because they often rely on subjective measures, such as clinical interviews and self-reported questionnaires like the PHQ-9 for depression, GAD-7 for anxiety, and the PSS for perceived stress.
A patient might have a difficult time expressing their perceived level of loneliness or its impact on conditions such as sleep, mental health, and cognitive performance. If the patient is reliant on a caregiver, there could be misalignment between the caregiver’s perspective and the patient’s own. Additionally, stigma can hinder both a patient’s willingness to disclose the extent of their loneliness and a provider’s ability to recognize the patient’s needs.
By digitizing standardized mental health questionnaires and combining them with objective cognitive assessments, Creyos Health offers a comprehensive platform to assess patients’ mental and cognitive health—including in the context of loneliness and its impacts.
The platform provides healthcare providers with a more comprehensive understanding of a patient's cognitive health and how it may be affected by loneliness and related mental health conditions. By tracking cognitive performance over time in the centralized Creyos Health platform, providers can identify early signs of cognitive decline in lonely people, tailor treatment plans based on individual needs, track the impact of interventions, and adjust treatment strategies as needed.
Addressing Loneliness with Data-Driven Care
Loneliness is a significant public health challenge with serious and long-lasting implications for brain health, including increased risk of depression, anxiety, cognitive decline, and physical wellbeing. By recognizing the critical role of social determinants of health, such as socioeconomic status, access to healthcare, and presence of social support networks, healthcare providers can take an active role in addressing the loneliness epidemic and improving the overall health of their patients.
For clinicians to provide effective patient-centered care, a data-driven approach is ideal. Comprehensive health assessments that include measurement and tracking of mental, cognitive, and physical health can help measure the negative effects of loneliness as a first step toward ending the epidemic.
Updated: March 10, 2025
Reviewed by Sydni Paleczny, Staff Scientist
Sydni earned her MSc in Neurosciences at Western University under Dr. Adrian Owen. Her research explores neuropsychological outcomes after cardiac surgery, with interests in cognitive neuroscience, critical care, and brain health. At Creyos, she supports scientific validity, health technology, and ongoing research.