Distribution of psychological distress is stable in recent decades and follows an exponential pattern in the US population

Shinichiro Tomitaka,Kazuki Ide,Yutaka Ono,Yohei Kawasaki,Toshi A Furukawa,Maiko Akutagawa

doi:10.1038/s41598-019-47322-1

Abstract

The prevalence of psychological distress is fairly stable in industrialised countries in recent decades, but the reasons for this stability remain unknown. To investigate the mechanisms underlying stability of psychological distress in the general population of the United States, we analysed the mathematical patterns of the distribution of psychological distress in recent decades. The present study utilised the Kessler psychological distress scale (K6) data from the 1997‒2017 United States National Health Interview Survey. We used overlap coefficients and graphical analysis to investigate the stability and mathematical patterns of the K6 distribution. Overlap coefficients and graphical analysis demonstrated that the distribution of K6 total scores was stable in the United States over the past two decades. Furthermore, the distributions of K6 total scores exhibited an exponential pattern, with the exception of the lower end of the distribution. These findings suggest that the lack of change in the prevalence of psychological distress over several decades is due to the stability of psychological distress distribution itself. Furthermore, the stability of the distribution of psychological distress over time may be linked to the exponential pattern of psychological distress distribution.

Highlights

Psychological distress is characterised by depressive and anxiety symptoms, and is an indication of common psychiatric conditions such as depression and anxiety disorders[1]
A population-based study conducted in Taiwan using the 12-item Chinese Health Questionnaire (CHQ), which is a self-administered screening instrument widely used to identify non-psychotic mental disorders in Chinese populations[13], showed a two-fold increase in the prevalence of common mental disorders between 1990 and 201014
Distress due to social distress has been masked by a concurrent increase in treatment[9]. Another explanation is that reductions in prevalence due to treatment have been masked by an increase in reporting of symptoms due to greater public awareness of common mental disorders[15]

Summary

Introduction

Psychological distress is characterised by depressive and anxiety symptoms, and is an indication of common psychiatric conditions such as depression and anxiety disorders[1]. The majority of studies in the US, Australia, UK, and Japan, which mostly used the K6, have reported little to no change in the prevalence of psychological distress and depression in the general population in recent decades[7,8,9,10,11,12]. Distress due to social distress has been masked by a concurrent increase in treatment[9] Another explanation is that reductions in prevalence due to treatment have been masked by an increase in reporting of symptoms due to greater public awareness of common mental disorders[15]. It is necessary to consider why the prevalence of psychological distress is stable in recent decades

Methods

Results

Conclusion