Recognising loneliness in people with substance use disorders

The recent pandemic revealed a close link between feeling lonely and increased substance use which, in turn, can damage relationships and create a cycle of loneliness. In this blog Jonathan Crabtree, Postgraduate researcher at King's IoPPN and NIHR Maudsley BRC's CEDI lead, Dr Mariana Pinto da Costa, a Senior Lecturer at King's IoPPN and a Consultant Psychiatrist at South London and Maudsley NHS Foundation Trust, explore the link between loneliness and substance use disorders using real-world clinical data.

Why loneliness matters

We all need connection. Friends, family, colleagues, neighbours – these relationships protect us from stress, help us bounce back from challenges, and make life more meaningful. But loneliness is not the same thing as being alone. It’s the gap between the relationships we have and the ones we would like to have. That gap can take a serious toll, and it is increasingly recognised as a public health concern, linked to depression, heart disease, and even earlier mortality.

Substance use disorders - which involve the uncontrolled use of substances such as alcohol or cannabis despite their harmful effects - can have a deep impact on health. They affect individuals, families, and communities, and are among the most stigmatised health conditions. In England, the number of adults receiving treatment for substance misuse increased by 7% last year, the biggest increase since 2009. Almost three-quarters of people in addiction services also need mental health support.

The COVID-19 pandemic shone a spotlight on the link between feeling lonely and increased substance use – and how substance use, in turn, can damage relationships, creating a cycle of loneliness. Our recent research set out to understand more about this link.

Looking at real-world data

To understand more about how loneliness relates to mental health and healthcare outcomes for people with substance use disorders, we analysed de-identified electronic health records (EHR) data from South London and Maudsley NHS Foundation Trust, accessed via the Clinical Record Interactive Search (CRIS) platform.

Our study included 1,870 patients diagnosed with a substance use disorder between 2016 and 2023. We used natural language processing, a technique to scan clinical notes for mentions of the words “lonely” and “loneliness”. This approach allowed us to capture real-life accounts recorded during routine care and insights that go beyond standard questionnaires.

We then examined whether loneliness was linked to:

• Time to first crisis episode
• Time to emergency presentation
• Duration of mental healthcare use
• Number of contacts with clinical services
• All-cause mortality

By adjusting for a range of demographic and clinical factors, we could focus on the potential role of loneliness itself and we found that more than one in four patients with a substance use disorder (27.3%) had a recorded mention of loneliness in their clinical notes. This group was significantly more likely to experience crisis episodes, emergency presentations, more days receiving mental healthcare, and a higher number of face-to-face clinical contacts with clinical services. These differences remained even after accounting for other factors that could influence these outcomes.

We also found that people with recorded loneliness were more likely to have a co-occurring mental health condition - sometimes called a “dual diagnosis” - and a higher risk of a range of mental health symptoms.

When we looked at specific groups - alcohol, cannabis and opioids use disorders - loneliness was linked to poorer outcomes in all three, such as increased risk of crisis episodes, emergency presentations, days of mental healthcare receipt and number of contacts with clinical services. The impact was greatest for people with opioid use disorders, who had the highest risk of crisis episodes, emergency presentations, contacts with clinical services and mental health symptoms.

Addressing loneliness

Our findings show that loneliness is a significant risk factor for increased mental health symptoms and poorer healthcare outcomes in people with substance use disorders. This highlights the importance of routinely asking about, and recording, patients’ feelings of loneliness which can often be overlooked in discussions in healthcare services.

Our study also shows that loneliness has a real and measurable impact on health outcomes. Services can act on this insight, by recognising and addressing social and community support as part of routine care to meet the needs of this vulnerable patient group.

Addressing loneliness could help break the cycle between feeling lonely and poor health, ultimately supporting better recovery.

To improve recovery outcomes for people with substance use disorders, we need to look beyond treating substance use itself. Our hope is that these findings will help reduce stigma while deepening understanding of the fundamental human need for connection, which is vital for treatment and recovery.

 
The relationship between loneliness and adverse clinical health in substance use disorders: a retrospective cohort study from south London, (Jonathan Pierce Crabtree, Gayan Perera, Robert Stewart, Mariana Pinto da Costa) was published in Journal of Psychiatric Research, Volume 190, 2025, Pages 364-371.