Feeling lonelier than usual is linked to increased drinking and drug use, according to detailed pandemic diaries

During the pandemic, on days that adults felt particularly lonely or when lockdown restrictions were more limiting, they used more drugs (other than cannabis), a new study suggests. When people's loneliness was severe, they were also more likely to drink alcohol.

The findings come from the first large-scale pandemic study in which participants kept daily diaries of their mood and substance use, and may help inform more effective treatments for people with substance use disorders (SUD). The COVID-19 pandemic was accompanied by increases in loneliness and in substance use. For the study in Alcoholism: Clinical & Experimental Research, investigators explored associations between these phenomena over 30 days.

Restricted social contact during the pandemic has already been linked to intensified isolation and stress, as well as rising anxiety, depression, drinking, cannabis use, and fatal drug overdoses. The relationship between loneliness and substance use is not well understood, however. Past research findings have been mixed, reflecting in part differences in how shifts in loneliness are construed—for example, as an individual's fluctuating levels of loneliness ("within-person"), or that individual's loneliness compared to others' ("between-person").

The researchers worked with 2,650 US adults recruited between October 2020 and May 2021. Their average age was 39, two in three were women, and 40% were BIPOC. Participants completed baseline surveys that covered demographic information, psychological and behavioral health, and more.

They were asked to fill out a daily diary for 30 days on their mood, activities, health, substance use, and social interactions (answering, for example, "How lonely were you today?"). The researchers also measured the level of COVID-19 restrictions in place at the time. They used statistical analysis to examine links between substance use and individuals' fluctuating loneliness relative both to their own mood and to others'.

The associations between participants' loneliness and substance use varied. People who tended to feel lonelier than other participants were more likely to use non-cannabis drugs daily. This was attributed largely to depression, which frequently co-occurs with loneliness. On days when participants felt lonelier than usual, however, and when lockdown restrictions were more severe, they were also more likely to use drugs other than cannabis—independent of depression.

Loneliness affected their alcohol consumption, too. People drank more on days when they were either "much lonelier than usual" or "much less lonely than usual;" most of the variance in participants' daily number of alcoholic drinks (59%) was related to fluctuations in their own loneliness ("within-person"). People who tended to feel lonelier than other participants were more likely to use cannabis—but when they felt lonelier than usual, they were less likely to use it. (This may reflect the middle/older age of this sample; in other studies, young adults' loneliness has been linked to frequent cannabis use).

The findings confirm that social restrictions place people at heightened risk for substance use, and that severe loneliness is a risk factor for increased drinking. The researchers warn that people with SUD whose loneliness increases during treatment and recovery likely face a higher risk of substance use. "Just in time" digital interventions, for example via smartphone, may help mitigate this effect. Additional research is needed to know whether the study findings apply to the broader population.