Prevalence of Mild to Moderate Mental Illness, Correlates of Treatment Patterns, and Perceived Unmet Need among U.S. Adults: Results from the National Survey on Drug Use and Health, 2021

1. INTRODUCTION

Mental health issues affect millions of adults nationwide [1]. Nearly half of adults will meet criteria for one or more diagnosable mental disorders over the course of a lifetime [2]. Despite the availability of evidence-based treatments, less than half of those with any mental illness (AMI) report receiving treatment in the past year [1]. Treatment gaps exist due to many barriers to accessibility and delivery of care. Coupled with a nationwide shortage of mental health providers to meet the need of those with mental health issues [3, 4], adults cite cost, limited time to seek and receive care, not knowing where to go to receive services, and not having transportation to travel when they are able to make an appointment, stigma, and not believing treatment is necessary as barriers to care receipt [1]. In addition to the increased prevalence and demand for mental health services during the COVID-19 pandemic [5], other barriers to access were created by the fear of transmission [6], as healthcare, including mental health services, shifted toward increased virtual delivery [7].

Since the advent of the pandemic, the prevalence as well as the appropriateness and effectiveness of the virtual delivery of mental health services, including for those with mental health concerns accompanied by more severe forms of impairment, have been demonstrated [8-10]. It is undeniably important to study serious mental illness (SMI) as a separate category of individuals with unique characteristics and associated treatment needs, given levels of impairment and disparities experienced [11]. Indeed, the Substance Abuse and Mental Health Services Administration (SAMHSA) sponsors a nationally representative, annual survey, the National Survey of Drug Use and Health (NSDUH), to estimate the past-year prevalence of United States (U.S.) adults living with SMI, in part to assist with planning for services at the state level [12]. The algorithms created for use with NSDUH data also allow for the estimation of AMI. Although SAMHSA annually releases detailed tables reporting the past-year prevalence of individuals with AMI but not SMI (i.e., mild to moderate mental illness; MMMI), as well as the prevalence of MMMI and its treatment landscape (including the perceived unmet need for mental health services), these reports have not, to the authors’ knowledge, been distributed in the peer-reviewed literature, setting the stage for the current study. Since this study is exploratory, no specific hypotheses were tested.

Although studies have reported a net benefit of treatment for those with MMMI [13], a finer-grained understanding of this population, its characteristics, and its needs will help optimize treatment equity and capacity. This is especially true given the recent proliferation of virtual services, such as telehealth and digital mental health interventions (DMHIs), since the pandemic, which could potentially benefit those with MMMI and allow in-person services to be reserved for those with higher acuity needs. In addition, the prevalence correlates specific to MMMI have not been reported, precluding clarity about groups of adults suffering disparities. Identifying adults with increased risk of MMMI and groups less likely to get treatment and more likely to perceive an unmet need for care is an important first step towards improving mental health equity.

2. METHODS

3. RESULTS

4. DISCUSSION

Results from this study indicate that nearly 44 million community-dwelling U.S. adults were classified as having an MMMI in 2021, representing about 1 in 6 adults living in the household population captured by NSDUH survey methods. This is in addition to the 14 million classified as having SMI [22]. To the authors’ knowledge, this is the first report in the peer-reviewed literature of the national prevalence of MMMI. Despite the proliferation of new modalities for delivering mental health treatment, such as synchronous or asynchronous telehealth, only about 2 in 5 adults with MMMI reported receiving past-year mental health treatment in 2021. Notably, among those with MMMI who did receive care, over 3 in 5 received it virtually.

The year 2021 was at the height of the COVID-19 pandemic, which may have influenced the choice of treatment setting. Nonetheless, 2022 NSDUH data released after this study’s analyses indicated that a comparable proportion of those with MMMI who received treatment also did so virtually [1]. The trend toward increased use of virtual services for mental health treatment since the pandemic is likely to endure, and the future treatment landscape will probably include a mix of telehealth modalities (e.g., treatment or counseling via phone, email, or videoconference) and mobile technologies, such as DMHIs. However, receipt of treatment does not necessarily indicate the adequacy of the services received. Therefore, additional studies are needed to investigate the nature of the treatment, particularly the types of virtual services being utilized.

Although some questioned the helpfulness of treating those with milder levels of mental illness severity, heightened risk for later negative clinical outcomes among even milder cases has been recognized [13]. Importantly, about 1 in 5 of those with MMMI, representing over 8 million adults, indicated a perceived unmet need for such services. This proportion was higher among those who had received past-year care than among those who had not (23.6% vs. 17.3%). These findings are in line with prior work demonstrating that perceived unmet need likely drives care-seeking [23] and that those receiving treatment may still perceive that their overall needs are not being met by current standards of care [24]. The most prevalent barriers noted among those with MMMI who perceived an unmet need, mainly cost, time, and inability to know where to go for care, suggest a possible role for newer care modalities such as easily accessible, low-cost DMHIs that can be used on demand at any time.

The sociodemographic correlates of mental health-related factors identified by adjusted analyses in this study highlight important disparities that still exist. Younger adults aged 18–25 years, females, those identifying as non-Hispanic or Latino with more than one race, part-time or unemployed individuals, those living below 100% of the poverty line, those with Medicaid insurance, those in less than excellent health, and individuals not identifying as heterosexual had higher prevalence estimates of MMMI than their respective reference categories. Interestingly, college graduates had higher past-year prevalence estimates compared with adults with lower levels of education. Although recent evidence points to attendees of higher education institutions having higher rates of mental disorders than their counterparts not attending school, some research has determined that these differences did not persist into later adulthood [25, 26]. Other studies have reported contradictory findings; however, factors such as having more stressful jobs are a potential reason for higher distress among more educated subgroups (see World Health Organization, n.d. for more information [27]).

Among those with MMMI, males had a lower prevalence of past-year mental health service receipt compared to females, which is important given the apparent rising prevalence in this population [1]. However, females with MMMI were more likely than males to report a perceived unmet need for treatment. One possible reason for this disparity could be stigma, which some have explored as contributing to differing treatment receipt rates between males and females [28, 29]. Other sociodemographic groups, such as adults identifying as Hispanic, displayed a similar pattern: they were less likely to receive care but also less likely to perceive an unmet need for it, potentially for similar reasons [30]. Conversely, adults with MMMI identifying as bisexual were more likely to receive past-year care but also more likely to perceive an unmet need, compared to adults identifying as heterosexual. Recent studies on the distinctive needs of sexual minorities suggest unique experiences of mental health issues, treatment receipt, and perceived unmet care [31].

Other important population groups with MMMI, such as non-Hispanic Black, non-Hispanic Asian individuals, and those with no insurance, had lower prevalence of past-year treatment, while groups like younger adults aged 18–25 years had higher unmet need among those not receiving past-year care. These findings replicate prior epidemiological research demonstrating care disparities that adversely affect traditionally underserved groups [24, 32].

Barriers to mental health care reported by at least 1 in 5 adults with MMMI who perceived an unmet need for mental health services include cost, time, not knowing where to go, and believing they could handle issues on their own. The deepening mental health crisis in the U.S [33]. underscores the urgent need for new ways to access and receive mental health care by those in need. Innovations in policy, public health, and technology will likely all be necessary to address this crisis. Regarding the latter, carefully curated DMHIs have been developed with demonstrated benefits that appear to outweigh tested harms [34, 35]. Continued innovation of these solutions may help reduce the nation’s mental health burden.

5. LIMITATIONS

The findings from this study should be considered in light of several important limitations resulting from the use of secondary data collected as part of a cross-sectional national surveillance effort, which does not permit exploration of causal relationships [36]. First, the sample included only adults living in households or noninstitutionalized group settings, excluding populations with some of the highest mental health needs, such as homeless individuals, long-term hospitalized patients, active-duty military personnel, and incarcerated adults [37]. Thus, these findings do not represent the complete picture of the U.S. mental health landscape, but only that experienced by community-dwelling adults. Second, mental illness categorization relied on a statistical model developed using 2008–2012 data rather than direct clinical interviews. Nonetheless, these models were carefully calibrated against interviewer-assessed DSM-IV criteria-based mental disorders [38] and continue to serve as the method used by states to quantify mental health block grant allocations issued annually in the U.S [12].

In the absence of nationally representative psychiatric epidemiological data to enable quantification of MMMI since the National Comorbidity Survey-Replication was conducted several decades ago [13], these data are widely used to quantify the mental health needs of the U.S. adolescents and adults. It, therefore, is unknown how the update to DSM-5 could affect these estimates [39]. Furthermore, SAMHSA refers to virtual mental health services in the NSDUH as essentially synonymous with telehealth to “include treatment/counseling for mental health, emotions, or behavior over the phone, by email, or through video calling” [21]. This definition makes it unclear how survey respondents should consider technologies such as DMHIs which may not require a direct line of communication between user and healthcare professional. Finally, this study relied on self-reported data, which potentially introduced social desirability and recall biases. In 2021, however, the NSDUH offered multimodal participation via web and, if preferred, in-person interviews [12].

In the absence of nationally representative psychiatric epidemiological data to enable quantification of MMMI since the National Comorbidity Survey-Replication was conducted several decades ago [13], these data are widely used to quantify the mental health needs of U.S. adolescents and adults. It, therefore, is unknown how the update to DSM-5 could affect these estimates [39]. Furthermore, SAMHSA refers to virtual mental health services in the NSDUH as essentially synonymous with telehealth, including “treatment/counseling for mental health, emotions, or behavior over the phone, by email, or through video calling” [21]. This definition makes it unclear how survey respondents should consider technologies, such as DMHIs, which may not require a direct line of communication between the user and healthcare professional. Finally, this study relied on self-reported data, which potentially introduced social desirability and recall biases. In 2021, however, the NSDUH offered multimodal participation via web and, if preferred, in-person interviews [12].

CONCLUSION

This study is likely the first of its kind to report nationally representative estimates and correlates of MMMI in the U.S. community-dwelling adult population. In 2021, MMMI affected over 46.7 million American adults, with only 41.3% receiving mental health treatment over the course of the year. In addition to the majority using prescription medications, the receipt of virtual services was reported by over 3 in 5 of those who received past-year treatment, which was greater than the proportion using non-virtual outpatient services. A total of 8.4 million adults reported an unmet need for services, with the most frequently cited barriers being cost, time, not knowing where to go for services, and thinking they could handle the issues on their own. Significant associations with MMMI, the receipt of treatment, and/or having a perceived unmet need for care were found across varying sexes, race/ethnicities, education levels, sexual orientation categories, and insurance status, suggesting that continued efforts to decrease these inequities are needed. Findings suggest the need for additional low-cost, easily accessible, on-demand mental health services to better meet the needs of adults with MMMI.

REFERENCES