Abstract
Background:
Mental illness diagnostic criteria are made based on assumptions. This pilot study aims to assess the public’s perspectives on mental illness diagnoses and these assumptions.
Methods:
An anonymous survey with 30 questions was made available online in 2021. Participants were recruited via social media, and no personal information was collected. Ten questions focused on participants’ perceptions regarding mental illness diagnoses, and 20 questions related to the assumptions of mental illness diagnoses. The participants’ perspectives on these assumptions held by professionals were assessed.
Results:
Among 14 survey participants, 4 correctly answered the relationships of 6 symptom pairs (28.57%). Two participants could not correctly conduct the calculations involved in mood disorder diagnoses (14.29%). Eleven (78.57%) correctly indicated that 2 or more sets of criteria were available for single diagnoses of mental illnesses. Only 1 (7.14%) correctly answered that the associations between symptoms and diagnoses were supported by including symptoms in the diagnostic criteria of the diagnoses. Nine (64.29%) correctly answered that the diagnosis variances were not fully explained by their symptoms. The confidence of participants in the major depressive disorder diagnosis and the willingness to take medications for this diagnosis were the same (mean = 5.50, standard deviation [SD] = 2.31). However, the confidence of participants in the symptom-based diagnosis of non-solid brain tumor was significantly lower (mean = 1.62, SD = 2.33, p < 0.001).
Conclusion:
Our study found that mental illness diagnoses are wrong from the perspectives of the public because our participants did not agree with all the assumptions professionals make about mental illness diagnoses. Only a minority of our participants obtained correct answers to the calculations involved in mental illness diagnoses. In the literature, neither patients nor the public have been engaged in formulating the diagnostic criteria of mental illnesses.
Introduction
Mental illnesses are associated with a large global disease burden (). In 2016, more than one billion people were affected by mental or addictive disorders (). In terms of disability-adjusted life years, mental and addictive disorders account for 7% of the global disease burden in 2016 (). To identify patients, mental illness diagnoses often are made based on symptoms (). The Diagnostic and Statistical Manual of Mental Disorders (DSM) provides lists of symptoms that mental health professionals use to make diagnoses (). However, these mental illness diagnoses are not without some concerns. For example, using the DSM or the International Classification of Diseases (ICD), different diagnosis criteria can coexist for the same diagnoses (–). Consistent principles regrading symptom selection and symptom duration are lacking with respect to formulating diagnostic criteria across diagnoses (). Moreover, an overlap in symptoms across diagnoses is not uncommon (). In addition, the role of trauma may be undervalued in diagnoses (). Thus, some have argued that mental illness diagnoses are scientifically meaningless ().
In addition, symptom-based diagnostic criteria are composite measures subject to problems that undermine their validity (–). The diagnoses of three common mental illnesses, dysthymic disorder, major depressive episodes (for the diagnosis of major depressive disorder or bipolar disorder according to the DSM, 4th edition, text revision [DSM-IV-TR]), and manic episodes (for the diagnosis of bipolar disorder), are, in fact, complicated mathematical equations that use data processing procedures that introduce biases into the diagnoses (). Under most circumstances, the diagnoses of these three illnesses cannot be fully explained by their own input symptoms (). In other words, biases have been introduced to these three diagnoses with few exceptions ().
In addition, several implicit assumptions are embedded in mental illness diagnostic criteria. The prevalence of these three diagnoses are determined by the diagnostic criteria, input symptom prevalence, and symptom correlations (). Although the major or minor criteria for mental illness diagnosis seem to suggest the relative importance of all symptoms, certain input symptoms in the minor criteria are unexpectedly more important than the others ().
Recently, awareness has grown concerning patient perspectives about mental health, particularly mental health care and quality of care (). Nevertheless, we are worried that the perspectives of patients and the public are still lacking with respect to mental illness diagnoses. The DSM 5 diagnoses have been criticized for a lack of recognizing individual experiences (). Moreover, our study did not find any relevant studies that used the public’s perspective to assess the diagnostic criteria of mental illnesses. Thus, the present study aims to assess the DSM diagnostic criteria from the public’s perspective by using an anonymous survey.
Materials and Methods
Beginning in 2021, our pilot study made an anonymous survey available online (take this fun survey below before continuing reading)1. We developed this survey based on recent studies concerning the assumptions made about mental illness diagnostic criteria (). The survey had 30 questions in total. Ten questions focused on participants’ perceptions about, or confidence in mental illness diagnoses. The ratings ranged from 0 to 10. The other 20 questions related to the assumptions professionals make about mental illness diagnostic criteria (). The survey questions about these assumptions, particularly the relationships between symptoms and diagnoses, were derived from the results in a publication (). The survey questions about the equations that represent the diagnostic criteria of three mental illnesses were based on published information (). The equations depict how information about symptoms is used to generate diagnoses (). Based on these equations, participants were invited to do the calculations and obtain diagnoses using the presence and absence of input symptoms. The survey questions concerning the relationships between mental symptoms were based on the DSM-IV-TR criteria. Correct or suggested answers to the 20 questions were obtained from relevant literature.
We posted survey invitations to the public on social media. We provided the purpose of the survey and an introduction to the survey questions on the consent page. Survey participation was completely voluntary, and withdrawal was allowed at any time. We did not ask questions about participants’ demographic characteristics or personal information that could be used to identify individuals, including names, job titles, addresses, and Internet Protocol (IP) addresses. We asked one question about whether they were mental health professionals to assess whether they had in-depth knowledge about mental illness diagnostic criteria, but not to identify them as the individuals.
Data Management and Analysis
We summarized continuous variables as mean values and standard deviations (SDs) and compared medians using the Wilcoxon rank sum test (, ). We summarized categorical variables in percentages. We considered a two-tailed p value less than 0.05 as statistically significant. We conducted data management and statistical analyses with R (v4.0.3) () and RStudio (v 1.4.1106) ().
Ethics Review
This study was reviewed and approved by the Veritas Independent Review Board (2021-2804-7063-7). We conducted our survey in accordance with the Declaration of Helsinki. Only adults were allowed to participate as specified in the informed consent form2. All participants provided consent for research use.
Results
Among 14 survey participants, 11 answered all the questions (79%). None of the respondents were mental health professionals, and all knew that mental illness diagnoses often were made based on symptoms (100%).
Perception of the Role of Symptoms
We assessed participants’ perceptions about the role of mental symptoms using several questions (see Table 1). First, we asked them whether the roles of six pairs of symptoms were the same or otherwise. All participants answered these six questions (100%), and four correctly answered all of them (29%).
TABLE 1
| Symptom pairs | Correct or suggested answers | Incorrect answers |
| Q5: “sleep too much” and “insomnia” | (1) Same role | (2) Opposite |
| N | 9 | 5 |
| % | 64.29% | 35.71% |
| Solution: “sleep too much” and “insomnia” are two symptoms that constitute a criterion in the minor criteria for the diagnosis of major depressive | ||
| episodes and dysthymic disorder | ||
| Q6: “decreased need for sleep” and “insomnia” | (1) Different roles | (2) Same role |
| N | 7 | 7 |
| % | 50% | 50% |
| Solution: “decreased need for sleep” is a symptom in the minor criteria for the diagnosis of manic episodes; “insomnia” is a symptom in the minor | ||
| criteria for the diagnosis of major depressive episodes and dysthymic disorder | ||
| Q7: “depressed mood” and “diminished interest or pleasure” | (1) Different roles | (2) Same role |
| N | 7 | 7 |
| % | 50% | 50% |
| Solution: “depressed mood” is a symptom in the major criteria and “diminished interest or pleasure” is a symptom in the minor criteria for the | ||
| diagnosisof major depressive episodes | ||
| Q8: “unintentional weight loss” and “unintentional weight gain” | (1) Same role | (2) Different roles |
| N | 9 | 5 |
| % | 64.29% | 35.71% |
| Solution: “unintentional weight loss” and “unintentional weight gain” are two symptoms that constitute a criterion in the minor criteria for the | ||
| diagnosis of major depressive episodes | ||
| Q9: “poor appetite” and “overeating” | (1) Same role | (2) Different roles |
| N | 9 | 5 |
| % | 64.29% | 35.71% |
| Solutions: “poor appetite” and “overeating” are two symptoms that constitute a criterion in the minor criteria for the diagnosis of dysthymic disorder | ||
| Q10: “poor concentration” and “distractibility” | (1) Different roles | (2) Same role |
| N | 7 | 7 |
| % | 50% | 50% |
| Solution: “poor concentration” is a symptom in the minor criteria for the diagnosis of dysthymic disorder; “distractibility” is a symptom in the minor | ||
| criteria for the diagnosis of manic episodes | ||
| Q5–Q10 | All correct | Incorrect, at least once |
| N | 4 | 10 |
| % | 28.57% | 71.43% |
Participants’ perception about the assumed relationships between mental symptoms.
Diagnostic criteria of major depressive episodes, dysthymic disorder, and manic episodes based on the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision ().
Calculations Involved in the Diagnosis
We asked participants to do the calculations involved in the diagnosis of the three conditions. Two participants replied with incorrect answers for all the three calculations (14.29%, Table 2). Five participants (35.71%) considered these calculations closely related to the mental illness diagnoses. Two participants did not answer which equations represented mental illness diagnoses (14.29%). Five (35.71%) correctly indicated the three diagnoses represented by the equations.
TABLE 2
| Calculations for the diagnosis | Correct answers | Incorrect answers | ||
| (Q11) Calculation for the diagnosis of major depressive episodes: 1 × 0 × (1 + 1 + 1 + 0 + 1 + 0- 3) + (1- 1 × 0) × (1 × 0) × (1 + 1 + 1 + 0 + 1 + 0 + 1–4) | (1) Answer is 0 | (2) Answer is 1 | ||
| N | 12 | 2 | ||
| % | 85.71% | 14.29% | ||
| (Q12) Calculation for the diagnosis of dysthymic disorder: 1 × 0 | (1) Answer is 0 | (2) Answer is 1 | ||
| N | 12 | 2 | ||
| % | 85.71% | 14.29% | ||
| (Q13) Calculation for the diagnosis of manic episodes: (1- 1 × 0) × (1 + 0) × 1 × (1 + 0 + 0 + 0 + 0 + 1 + 1-3) + (1 – (1 – 1 × 0) x (1 + 0)) × 1 × (1 + 0 + 0 + 0 + 0 + 1 + 1–3) | (1) Answer is 0 | (2) Answer is 1 | ||
| N | 12 | 2 | ||
| % | 85.71% | 14.29% | ||
| Q11– Q13 | All correct | Incorrect, at least once | ||
| N | 12 | 2 | ||
| % | 85.71% | 14.29% | ||
| (Q14) Calculations closely related to diagnoses | (1) Closely related | (2) Not related | ||
| N | 5 | 9 | ||
| % | 35.71% | 64.29% | ||
| (Q15) The diagnosis represented by the equation: A_ma1 × A_ma2 × (A_mi3 + A_mi4 + A_mi5 + A_mi6 + A_mi7 + A_mi8 + A_mi9 + A_bias1) + (1- A_ma1 × A_ma2) × (me_ma1 × A_ma2) × (A_ mi3 + A_mi4 + A_mi5 + A_mi6 + A_mi7 + A_mi8 + A_mi9 + A_bias2) | (1) Major Depressive Episodes | (2) Dysthymic Disorder | (3_) Manic episodes | NA |
| N | 6 | 5 | 1 | 2 |
| % | 42.86% | 35.71% | 7.14% | 14.29% |
| (Q16) The diagnosis represented by the equation: A_ma × A_mi | (1) Dysthymic Disorder | (2) Major Depressive Episodes | (3) Manic Episodes | NA |
| N | 7 | 4 | 1 | 2 |
| % | 50% | 28.57% | 7.14% | 14.29% |
| (Q17) The diagnosis represented by the equation: (1- A_ma1 × A_ma2) × (A_ma1 + A_ma2) × A_ma3 × (A_mi1 + A_ mi2 + A_mi3 + A_mi4 + A_mi5 + A_mi6 + A_mi7 + A_bias1) + (1 – (1 – A_ma1 × A_ma2)(A_ma1 + A_ma2)) × A_ma3 × (A_mi1 + A_ mi2 + A_mi3 + A_mi4 + A_mi5 + A_mi6 + A_mi7 + A_bias2) | 1. Manic Episodes | 2. Dysthymic Disorder | 3. Major Depressive Episodes | NA |
| N | 5 | 3 | 4 | 2 |
| % | 35.71% | 21.43% | 28.57% | 14.29% |
| Q15–Q17 | All correct | Incorrect, at least once | NA | |
| N | 5 | 7 | 2 | |
| % | 35.71% | 50% | 14.29% | |
Calculations involved in the diagnosis of major depressive episodes, dysthymic disorder, and manic episodes.
NA, no answer.
Equations published elsewhere ().
Assumptions About Mental Illness Diagnoses
We asked participants about the assumptions underlying mental illness diagnoses (Table 3). Eleven (78.57%) correctly indicated that two or more sets of criteria were available for single diagnoses of mental illnesses. Only 1 (7.14%) correctly answered that the association between symptoms and diagnoses was supported by making sure that the diagnostic criteria of the diagnosis included these symptoms. Four (28.57%) wrongly indicated that this causal relationship needed to be proved by examining the strengths of association between the diagnosis and the symptoms. Eight (57.14%) wrongly indicated that the causal inference should be made by looking for pathological or biological evidence. Nine (64.29%) correctly answered that the diagnosis variances could not be fully explained by its symptoms. Thirteen (92.86%) correctly indicated that mental symptoms are more common than diagnoses, assuming similar symptom prevalence and correlations. Only one participant (7.14%) correctly answered all four questions concerning assumptions about mental illness diagnoses.
TABLE 3
| Assumptions of mental illness diagnoses | Correct answers | Incorrect answers | ||
| (Q18) Single set of diagnostic criteria for mental illnesses | (1) No, 2 or more sets of criteria for a single diagnosis. | (2) Of course, 1 set for an illness. | ||
| N | 11 | 3 | ||
| % | 78.57% | 21.43% | ||
| Solution: at least 3 sets of diagnostic criteria coexist: the Diagnostic and Statistical Manual of Mental Disorders (DSM), the International Statistical | ||||
| Classification of Diseases (ICD), and the Research Domain Criteria (RDoC, an approach by the National Institute of Mental Health) (, 70). | ||||
| (Q19) Causation of symptoms by illnesses | (1) Make sure the diagnostic criteria of the diagnosis include these symptoms | (2) Exam the strengths of association between the diagnosis and these symptoms | (3) Look for pathological or biological evidence to understand the relationship between the diagnosis and the symptoms | NA |
| N | 1 | 4 | 8 | 1 |
| % | 7.14% | 28.57% | 57.14% | 7.14% |
| Solution: symptoms are important measures to identify disorders and the evidence to support the causation between diagnoses and symptoms | ||||
| may be insufficient. (, ). | ||||
| (Q20) Diagnoses fully explained by symptoms | (1) NOT fully explained by symptoms | (2) Fully explained by symptoms | NA | |
| N | 9 | 4 | 1 | |
| % | 64.29% | 28.57% | 7.14% | |
| Solution: the diagnoses of major depressive episodes, dysthymic disorder, and manic episodes cannot be fully explained by their symptoms, assuming | ||||
| symptoms occurring with similar prevalence and similar correlations.()One exception is the diagnosis of dysthymic disorder that can be fully explained | ||||
| by its symptoms when the symptoms are randomly assigned to 70% of the population (). | ||||
| (Q21) Mental symptoms more common than diagnoses | (1) Yes. | (2) No. | NA | |
| N | 13 | 0 | 1 | |
| % | 92.86% | 0% | 7.14% | |
| Solution: the diagnoses of major depressive episodes, dysthymic disorder, and manic episodes occur less often than their input symptoms, assuming | ||||
| similar symptom prevalence and correlations.() | ||||
| Q18–Q21 | All correct | Incorrect, at least once | ||
| N | 1 | 13 | ||
| % | 7.14% | 92.86% | ||
Assumptions about mental illness diagnoses.
NA, no answer.
Symptoms Explaining Most of the Diagnosis Variances
The symptoms that explained most of the variances of the diagnoses were assessed by using R-squared in a published study () and participant ratings in our survey. The R-squared for the symptoms explaining the diagnosis variances was obtained from simulations assuming symptom prevalence as 0.3 and symptom correlations as 0.1 (). In Figures 1–3, the DSM-IV-TR criteria are listed and the text sizes of the symptoms are proportional to R-squared and participants’ ratings (proportions of participants selecting these symptoms). The R-squared and participants’ ratings for the symptoms explaining most of the variances of the diagnosis of major depressive episodes do not match in Figure 1. The symptom, “loss of interest or pleasure in daily activities,” in the major criteria was not considered as explaining most of the variances of the diagnosis by any participants (0%), but the R-squared was estimated to be 24.22%, which was higher than other symptoms. When we asked participants to choose whether “depressed mood” or “loss of interest or pleasure” explained more variances of the diagnoses of major depressive episodes, assuming a similar symptom prevalence, eight (57.14%) correctly answered “it depends.”
FIGURE 1
FIGURE 2

The symptoms that best explain the diagnosis of dysthymic disorder based on R-squared and participants’ ratings. DSM-IV-TR, Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision. Participants’ ratings, the proportions of all participants selecting the symptoms. *Percentages are the R-squared statistics representing the proportions of the variances of the diagnosis of dysthymic disorder explained by the symptoms, assuming symptom prevalence as 0.3 and symptom correlations as 0.1 (
FIGURE 3

The symptoms that best explain the diagnosis of manic episodes based on R-squared and participants’ ratings. DSM-IV-TR, Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision. Participants’ ratings, the proportions of all participants selecting the symptoms. *Percentages are the R-squared statistics representing the proportions of the variances of the diagnosis of manic episodes explained by the symptoms, assuming symptom prevalence as 0.3 and symptom correlations as 0.1 (
In Figure 2, the R-squared and participants’ ratings for the symptoms explaining most of the variances of the diagnosis of dysthymic disorder do not match, particularly for the symptoms in the minor criteria. In Table 4, when asked to choose the major or minor criteria that explained most of the variances of the diagnosis of dysthymic disorder, eight (57.14%) correctly chose the major criteria as explaining most of the variances of the diagnosis.
TABLE 4
| Symptoms better explaining diagnosis | Correct answers | Incorrect answers | |
| (Q23) “Depressed mood” or “loss of interest or pleasure” better explaining the diagnosis of major depressive episodes* | (1) It depends | (2) One of them | NA |
| N | 8 | 4 | 2 |
| % | 57.14% | 28.57% | 14.29% |
| (Q25) The major or minor criteria better explaining the diagnosis of dysthymic disorder* | (1) Major criteria | (2) Minor criteria | NA |
| N | 8 | 4 | 2 |
| % | 57.14% | 28.57% | 14.29% |
| (Q27) “Elevated,” “expansive,” or “irritable mood” better explaining the diagnosis of manic episodes* | (1) Only 1 of the 3 | (2) Equally | NA |
| N | 5 | 7 | 2 |
| % | 35.71% | 50% | 14.29% |
| Q23, Q25, and Q27 | All correct | Incorrect, at least once | NA |
| N | 2 | 10 | 2 |
| % | 14.29% | 71.43% | 14.29% |
Participants’ perception of the symptoms that better explain the diagnoses, assuming a similar symptom prevalence.
*Assuming the input symptoms occurring with similar prevalence and correlations (
In Figure 3, the R-squared and participants’ ratings for the symptoms explaining most of the variances of the diagnosis of manic episodes do not match, particularly for “irritable mood” in the major criteria and the symptoms in the minor criteria. In Table 4, when asked to choose which one of the three symptoms in the major criteria explained most of the variances of the diagnosis of manic episodes, five (35.71%) correctly chose only one of them as explaining more of the variances of the diagnosis, and seven (50%) incorrectly chose that these three symptoms equally explained the variances of the diagnosis.
Overall, only two participants (14.29%) correctly chose the symptoms that explained most of the variances of the three diagnoses.
Confidence in the Diagnosis
Participants rated their confidence in the diagnoses and the willingness to take medications to treat the associated symptoms using a scale from 0, not confident at all or not willing at all, to 10, very confident or very willing without conditions (Table 5). We invited participants to rate their confidence in two symptom-based diagnoses, major depressive disorder and non-solid brain tumor. According to an estimate, the medications to control symptoms are assumed to be effective for 40–60% of the patients, while placebo worked for 20–40% of patients (
TABLE 5
| Confidence on the diagnosis (0–10, from not confidence at all to very confident) | Statistics | |||||
| (Q3) Confidence on the diagnosis of major depressive disorder based on symptoms# | N | Mean | SD | Median | Min | Max |
| 14 | 5.50 | 2.31 | 5.5 | 1 | 9 | |
| (Q4) Willingness to take medication for symptoms* | N | Mean | SD | Median | Min | Max |
| 14 | 5.50 | 2.31 | 5.5 | 1 | 9 | |
| (Q28) Confidence on the diagnosis of non-solid brain tumor based on symptoms# | N | Mean | SD | Median | Min | Max |
| 13 | 1.62 | 2.33 | 1 | 0 | 7 | |
| (Q29) Willingness to take medication for symptoms* | N | Mean | SD | Median | Min | Max |
| 13 | 3.38 | 3.52 | 2 | 0 | 9 | |
| (Q30) Confidence on the diagnosis of mental illnesses in the end of the survey∧ | N | Mean | SD | Median | Min | Max |
| 13 | 3.92 | 2.72 | 5 | 0 | 8 | |
Confidence in symptom-based diagnoses and the willingness to take medications for symptom control.
#p < 0.001, based on the Wilcoxon rank sum test.
*p = 0.1, based on the Wilcoxon rank sum test. The medications were assumed to have the same efficacy to treat symptoms of the diagnoses: 40–60% effectiveness for patients, while placebo worked for 20% to 40% of the patients (
∧p = 0.16, compared with the confidence in the diagnosis of major depressive disorder based on symptoms (Q3) using the Wilcoxon rank sum test. SD, standard deviation.
Overall, no participants correctly answered all the 20 questions related to the assumptions about mental illness diagnoses.
Discussion
For more than a decade, mental illness diagnoses have been called wrong for several reasons, including the lack of validity (
Symptom Reporting Assumptions
For symptom-based diagnoses, the basic assumptions are that symptoms are reported accurately, interpreted in the same manner by both patients and clinicians, and documented precisely for making diagnoses. These assumptions do not seem to hold well. For example, symptoms are not accurately reported by patients with anxiety (
Symptom interpretation by clinicians is important, since it can influence treatment choices (
In the present study, the public did not interpret symptoms the same way as professionals. Less than 30% of the participants agreed with the professionally assumed relationships in six pairs of symptoms for the diagnosis of three mood disorders. One prominent example was that half of our survey participants considered “poor concentration” the same as “distractibility,” even though these two symptoms are used for exactly opposite diagnoses—dysthymic disorder and manic episodes—respectively.
Moreover, patient-reported symptoms may not be well documented by clinicians, even for well-defined symptoms, such as chest pain, dyspnea, and cough (
Relationships Between Symptoms
The relationships between symptoms (i.e., statistical correlations) are an important assumptions that not only determines the prevalence of a diagnosis, but also have important effects on the overlap and correlations among diagnoses (
More interestingly, the symptom pairs of different degrees of correlations have been used to construct single criteria items. For example, “insomnia” and “sleeping too much” are a pair of symptoms that do not occur together as often as “fatigue” and “loss of energy,” and these two pairs of symptoms are considered similarly important to the diagnosis of dysthymic disorder (
One neglected assumption concerning the relationships among symptoms is to put more weight on the symptoms that constitute single items of the major or minor criteria than on the symptoms that form pairs. For example, the symptom pair, “insomnia” or “sleeping too much,” is regarded as important for a diagnosis of major depressive episodes and dysthymic disorder as single symptoms, such as “recurrent thoughts of death.” Thus, having symptoms of “insomnia” and “sleeping too much” at the same time has the same diagnostic value as having “recurrent thoughts of death.” In such circumstances, any two symptoms used to form items of the major or minor criteria are given less weights.
Lastly, little information is available on the rationale for the weighting schemes imposed on the items (symptom pairs or single symptoms) of the major or minor criteria. In the minor criteria for the diagnosis of major depressive episodes, dysthymic disorder, and manic episodes, different items are given the same weights. This is a strong assumption for outcome prediction. When symptoms are used to predict outcomes in regression models, their regression coefficients are likely to vary in different magnitudes. In contrast, when symptoms are summed together as a diagnosis for outcome prediction, the regression coefficients of the input symptoms can in fact be represented by the coefficient of the diagnosis (
Composite Diagnostic Criteria Are Equations
Until recently, mental illness diagnoses were not recognized as composite diagnostic criteria that work as complicated equations that integrate information from input symptoms (
Although the diagnostic criteria can be transformed precisely into equations (
Other Assumptions
It is widely accepted by clinicians that more than one set of diagnostic criteria can apply to single mental illnesses, particularly when using the DSM and the ICD systems (
Although the causes of mental illnesses have been well discussed (
In addition to causal relationships, symptom-based diagnoses may not be explained fully by their symptoms due to the complicated diagnostic criteria that often distort the relationships between symptoms and diagnoses (
One related assumption of the diagnostic criteria is the implicit limitations on diagnosis prevalence. For example, in the minor criteria for the diagnosis of three mood disorders, the requirement of having multiple symptoms at the same time can lead to diagnoses less prevalent than their input symptoms (
Composite diagnostic criteria implicitly assume that patients with the same diagnoses are subject to similar treatment, since a common underlying cause has been identified (
Perception of Symptoms
The symptoms of the DSM diagnostic criteria are presented in an order that may suggest their importance. For example, the symptoms are grouped in the major and minor criteria for three mood disorders (
The design of diagnostic criteria puts more weights on certain symptoms that are not necessarily those in the major criteria or those that our survey participants considered more important (
Confidence in the Diagnosis
Few studies are available on individuals’ confidence in the diagnoses of mental illnesses, compared to the many studies on attitudes toward mental illness and care-seeking behavior (
Public and Patient Disengagement
Patient and public engagement has become an essential part of the evaluation of health technologies, since patients’ perspectives provide information that may help to improve the technologies under evaluation, and some of the patient-reported outcomes are not less important than those assessed by clinicians (
Moreover, the American Psychiatric Association (APA), the publisher of the DSM, has been proud of its explicit exclusion of non-health care professionals from participating in the DSM-5 Working Groups that formulate the diagnostic criteria for mental illnesses (
Composite Diagnostic Criteria Are Problematic
Composite diagnostic criteria that aggregate information from multiple symptoms or signs have been used widely in various medical diagnoses, including frailty (
These problems are more controllable if the composite diagnostic criteria are executed precisely and used with sufficient reliability amongst clinicians. However, the APA officially encourages clinicians to examine patients’ social, psychological, and biological factors and to use these factors for case formulation (67). In other words, diagnoses should consider implicit factors not mentioned in the DSM criteria. In reality, the reliability of case formulation varies across settings and awaits improvement (68). The reliability of case formulation does not seem good enough (69). In addition to the biases embedded in the DSM criteria (
In conclusion, if symptom-based diagnostic criteria are valid, reliable, and accurate enough, why are they not used to diagnose all medical conditions? Recent evidence shows that the problematic assumptions of the diagnostic criteria of mental illnesses may have been overlooked by mental health professionals (
Limitations
The conclusion that mental illness diagnoses are right or wrong is a judgment or an opinion, rather than a testable hypothesis. In the present study, we considered how the public interprets the diagnoses of mental illnesses and their confidence in symptom-based diagnoses using an online survey that involved technical terms in mental illnesses. This perspective is very different from that of mental health professionals who design, frame, and use mental illness diagnoses. Before the implementation of our study, we aimed to include professionals in our survey and have a question they could answer to self-identify whether they were mental health professionals. However, the recruitment was challenging and we lacked the resources to incentivize professionals to participate. Some mental health care professionals may think the public’s perspective fails to prove mental illness diagnoses wrong. We agree that this critique has its own basis and is an opinion based on mental health care professionals’ perspectives. This pilot study is a first attempt, with a limited sample size, to show professionals that their current diagnostic approach may be regarded wrong by the public. We will continue examining mental illness diagnoses using professionals’, patients’, and the public’s perspectives.
Moreover, the diagnostic criteria have been shifting from DSM-IV-TR to DSM-5 (
Conclusion
The diagnostic criteria of mental illnesses are based on various assumptions, many of which lack the evidence to support them, and which do not match the expectations of the public. For example, the assumed relationships between symptoms in six symptom pairs were not agreed by all our participants. Symptoms for the diagnosis of opposite mood disorders could be considered the same by public members. Symptom pairs of different degrees of correlations have been used to construct single items for diagnoses. Symptoms used to construct items for diagnosis have been implicitly given less weights than the symptoms used as single items. In the recent literature, diagnoses of mental illnesses have been recognized as composite diagnostic criteria that are complicated equations that integrate information from input symptoms.
In our study, a minority of our participants correctly linked the equations to the diagnoses they represented. Moreover, not all participants could correctly do the equation calculations. Not all participants agreed that there could be more than one set of diagnostic criteria for a single mental illness. Less than 8% approved using diagnostic criteria for causal inference. More than 25% thought diagnoses should be explained fully by their symptoms, although simulations proved otherwise. The symptoms used to diagnose mental illnesses are ordered based on their assumed importance. However, our participants considered some symptoms in the major criteria as not important at all for the diagnosis of mood disorders.
In our survey, confidence in the mental illness diagnoses and medications seems to be influenced by our participant’ understanding of how mental illnesses are diagnosed and whether the diagnosis is suggestive of biological roots. Participants were significantly less confident in a symptom-based diagnosis called “non-solid brain tumor,” compared with “major depressive disorder.”
The formulation of diagnostic criteria for mental illnesses lacks patient and public engagement. Recent evidence shows that the composite diagnostic criteria that the DSM uses to design mental illness diagnoses introduce biases into the diagnoses, link distinct populations to the same diagnosis, and may be associated with early terminations of trials. It is unclear when the DSM will begin to accept patients’ and the public’s perspectives, and understand the biases embedded in its composite diagnostic criteria.
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Statements
Data availability statement
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.
Ethics statement
The studies involving human participants were reviewed and approved by Veritas Independent Review Board (2021-2804-7063-7). Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements.
Author contributions
Y-SC conceptualized and designed this study, managed, and analyzed data and drafted the manuscript. C-JW assisted in data management and computation. Y-CL, H-TH, Y-PC, H-CW, S-YH, and W-CC participated in the design of this study. All the authors reviewed and approved the manuscript.
Conflict of interest
Y-SC is employed by the Canadian Agency for Drugs and Technologies in Health. Y-SC conducted this study as an independent researcher out of academic curiosity without any material support. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Footnotes
1.^https://docs.google.com/forms/d/e/1FAIpQLSdlulKwH5EigpuA9DKXc_KNrVPAnlErj9ioFMuqm5yZH7qTWQ/viewform?usp=sf_link or https://forms.gle/pT8W6zAY9kxgd8k59
2.^https://docs.google.com/forms/d/e/1FAIpQLSdlulKwH5EigpuA9DKXc_KNrVPAnlErj9ioFMuqm5yZH7qTWQ/viewform?usp=sf_link
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Summary
Keywords
mental illness, Diagnostic and Statistical Manual of Mental Disorders (DSM), International Classification of Diseases (ICD), assumption, confidence
Citation
Chao Y-S, Wu C-J, Lai Y-C, Hsu H-T, Cheng Y-P, Wu H-C, Huang S-Y and Chen W-C (2022) Why Mental Illness Diagnoses Are Wrong: A Pilot Study on the Perspectives of the Public. Front. Psychiatry 13:860487. doi: 10.3389/fpsyt.2022.860487
Received
23 January 2022
Accepted
14 March 2022
Published
29 April 2022
Volume
13 - 2022
Edited by
Roy Abraham Kallivayalil, Pushpagiri Medical College, India
Reviewed by
Elsheba Mathew, Pushpagiri Institute of Medical Sciences and Research Centre, India; Sudhir Bhave, N.K.P. Salve Institute of Medical Sciences and Research Centre, India
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Copyright
© 2022 Chao, Wu, Lai, Hsu, Cheng, Wu, Huang and Chen.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Yi-Sheng Chao, chaoyisheng@post.harvard.eduWei-Chih Chen, wiji.chen@gmail.com
This article was submitted to Public Mental Health, a section of the journal Frontiers in Psychiatry
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