Following COVID, mental health is front and center in the public consciousness.

Traditional and social media are awash with stories about new treatments, alarming increases in the prevalence of mental health problems and deficiencies in the mental health system. Personal accounts of living with mental health problems are being shared as never before.

This increased attention is likely to have many positive effects.

Growing public awareness should help boost mental health literacy, reduce stigma and encourage people to seek appropriate help. The raised profile of mental health should also galvanize efforts to improve the health system.

Despite these hopes, some commentators worry that greater attention to mental health may also have some downsides. Critics have argued that ordinary human experiences are increasingly pathologized by psychiatric classifications, like the DSM-5, resulting in overdiagnosis and over-medication.

Some writers even suggest that raising awareness of mental ill-health might backfire and inadvertently generate more mental health problems. Others claim that people's concepts of mental health are changing in ways that may have damaging consequences.

Our research group explored changes like this as examples of "concept creep," the historical tendency for harm-related concepts to expand their meanings.

For example, we have shown that as "trauma" has been popularized in recent years, it has broadened its meaning to include less severe experiences. Once it referred only to life-threatening events, but in everyday language it increasingly refers to almost any adversity.

Might the same process of concept creep occur for "anxiety" and "depression," two of the most common forms of distress associated with mental ill-health?

Influential writers American sociologist Professor Allan Horwitz and philosopher Professor Jerome Wakefield, propose that this has happened already within mainstream psychiatry, arguing that DSM often misdiagnoses adaptive anxiety and everyday sadness as mental disorders. The paper is published in the journal PLOS ONE.

Concept creep

To test whether "anxiety" and "depression" have crept or diluted in this way, our new study used the natural language processing methods we previously employed to study trauma.

We looked at how the two words' meanings have changed over the past half-century in two massive data sets ("corpora"), expecting to find that they would become less emotionally intense.

One corpus contained abstracts of more than 800,000 psychology articles published from 1970 to 2018. The other contained over half a billion words drawn from diverse everyday American English sources, like TV shows, fiction, newspapers and spoken language, over the same period.

The two corpora allow us to examine whether the meanings of "anxiety" and "depression" have changed in academic discourse and in society at large.

We located every appearance of "anxiety" and "depression" in each corpus and extracted all the words appearing shortly before and after each one. These collocated words represent the semantic company the concept keeps.

Historical changes in these collocates can help clarify how the meanings of "anxiety" and "depression" have evolved.

We evaluated the emotional severity of the collocates using established norms for their emotional meaning. While we thought the severity would decline over the years we found the exact opposite.

In both corpora, words surrounding "anxiety" and "depression" steadily became more emotionally severe, telling us that these words are now seen as more distressing than in previous decades.

Shifting meanings of 'anxiety' and 'depression'

Keen to understand why the meanings of "anxiety" and "depression" intensified rather than diluted, as our concept creep prediction anticipated, we explored which of their collocated words had changed over the decades.

Two trends that help explain our findings emerged.

First, "anxiety" and "depression" increasingly appeared close together. For example, "depression" was not among the top ten collocates of "anxiety" in the general corpus in the 1970s or 1980s, but by the 2000s and 2010s, it became the most common one.

Second, over the past five decades, the two concepts increasingly appeared in the vicinity of illness-related words—like "disorder" and "symptom." It tells us that "depression" and "anxiety" are increasingly understood as clinical phenomena.

Together, these two trends help to explain why "anxiety" and "depression" have come to have more severe connotations both in academic psychology and in everyday language use.

"Anxiety" and "depression" have come to be seen as a pathological couple.

Pathologized rather than normalized

Our findings, based on patterns of word use observed in vast data sets over half a century, suggest that anxiety and depression are more and more viewed through a clinical lens.

Although anxiety and depression can both be transient and functional everyday mood states, they are increasingly cast as disorders.

They have been pathologized rather than normalized.

Does this mean that "anxiety" and "depression" have not undergone concept creep? Not necessarily.

People may now use these words to refer to less severe phenomena than they once did and increasingly adopt a clinical understanding of them when they do.

So the concepts of anxiety and depression may have broadened, intensified and pathologized simultaneously.

The implications of that possibility may be concerning.

People should seek help when they experience clinically significant anxiety or depression. But if they view ordinary anxiety or depression as pathological, it may mean they seek unnecessary treatment and self-diagnose inappropriately.