By Emma Young

Loneliness not only feels bad, experts have characterised it as a disease that increases the risk of a range of physical and psychological disorders. Some national prevalence estimates for loneliness are alarming. Although they can be as low as 4.4 per cent (in Azerbaijan), in other countries (such as Denmark) as many as 20 per cent of adults report being either moderately or severely lonely.

However, there’s no established way of identifying loneliness. Most diagnostic methods treat it as a one-dimensional construct: though it can vary in degrees, someone is either “lonely”, or they’re not. A new approach, outlined in a paper published recently in Social Psychiatry and Psychiatric Epidemiology, suggests that loneliness should in fact be divided into three sub-types, two of which are associated with poor mental health.

Philip Hyland at Trinity College Dublin and colleagues studied a nationally representative sample of 1,839 US adults aged between 18 and 70, all of whom had experienced at least one traumatic event in their lifetime. (This allowed the team to also look for associations between childhood or adult trauma and loneliness.) Most were married or living with a partner.

Participants completed a six-item scale that measured feelings of “social loneliness” (focusing on perceptions of the quantity of one’s social relationships) and “emotional loneliness” (which focused on perceptions of the quality of one’s relationships). They also completed questionnaires assessing levels of childhood and adult trauma, depression and anxiety, and their psychological wellbeing.

Following convention, the 17.1 per cent of participants who scored a certain amount above the average loneliness score for the sample (by more than one standard deviation) were classified as “lonely” – a figure comparable to that found previously in many other countries.

However, the researchers also used a statistical technique to look for qualitative differences between the participants’ loneliness responses, and this revealed four distinct classes.

The first class – which they called “low loneliness” – was characterised by low scores on both types of loneliness, social and emotional. Just over half the participants fell into this category. The second class – “social loneliness” – making up 8.2 per cent of the sample, comprised people low on emotional loneliness, but high on social loneliness. The third class – “emotional loneliness” – made up just over a quarter of the total sample and was characterised by the opposite pattern of high emotional loneliness but low levels of social loneliness. People in the fourth and final “social and emotional loneliness” class, accounting for 12.4 per cent of the sample, scored high for both types of loneliness.

The researchers found a clear gradient of psychological distress across the classes. People in the low loneliness class were, predictably, least distressed, followed by people in the “social loneliness” class, then the “emotional loneliness” class, and finally the “social and emotional loneliness” class. In fact, people in both these last two classes had levels of symptoms of depression, anxiety and negative psychological wellbeing that were reflective of a psychiatric disorder.

In other words, quality of relationships appears more important to mental health than the sheer number of them.“These results indicate that while the experience of social loneliness is associated with slight diminutions in overall mental health, relative to the low loneliness class, the experience of emotional loneliness has a substantially greater, and more negative impact on overall mental health status,” the researchers write. “The combination of social and emotional loneliness is associated with the poorest mental health status,” they note.

People who belonged to the emotional loneliness class were more likely to be female, younger than average for the group, not in a relationship and to have suffered an increased number of childhood traumas. (Every childhood traumatic experience increased the odds of belonging to the emotional loneliness class by 28 per cent.) The same associations were true for the “social and emotional” loneliness class – except they were also characterised by a greater number of adult traumas.

At 39.0 per cent, the total percentage of participants who fell into the two loneliness classes characterised by clinically relevant levels of psychological distress was much higher than the 17.1 per cent loneliness figure obtained using the conventional one-dimensional approach. “This finding indicates that by recognising naturally occurring subtypes of loneliness, the number of people experiencing a form… that is likely to be of clinical relevance is more than double the number identified when loneliness is conceptualised as a unidimensional construct,” the researchers note.

The work suggests that in assessing loneliness, whether in an individual or at a national level, it’s important to recognise there are various subtypes. It also supports findings from some other studies that it’s the quality, not quantity, of your relationships that really matters. As the researchers conclude: “From a societal perspective, and in the interests of reducing the burden of psychological distress, efforts should be made to enhance the quality of social connections as opposed to promoting the virtues of larger social networks.”

—Quality not quantity: loneliness subtypes, psychological trauma, and mental health in the US adult population

Emma Young (@EmmaELYoung) is Staff Writer at BPS Research Digest