On research distinctions and clinical relevance in psychiatry

In the wake of Diagnostic and Statistical Manual of Mental Disorders 5 (DSM-5), there has been considerable debate over changes to psychiatric classifications. These range from contentious issues like Asperger’s being subsumed under the broader autism spectrum, to less controversial matters such as the removal of schizophrenia sub-diagnoses (e.g. paranoid, undifferentiated), which have been demonstrated to have limited utility. Continuous updates to diagnostic categories over time raise the question of the relevance of research-based classifications to clinical practice in psychiatry, a relationship that appears increasingly tenuous. The impending release of International Classification of Diseases 11 (ICD-11) is poised to further stoke this debate.

The Hippocratic Oath, as it applies to mental health care, speaks of ensuring adequate knowledge and ability in patient treatments. Consequently, it is our opinion that research outputs should be accessible to clinicians, and ultimately serve to improve clinical outcomes. Jaspers speaks of the need to consider the nature of the mental illness experience itself alongside studying the mechanisms underlying psychiatric phenomenology. Clinicians need a good grasp of the former in practice, while researchers would also benefit from incorporating it into the latter. This Jasperian consideration is critical to maintaining the relationship between increasing knowledge through research and improved clinical practice. Some of these issues have recently been raised in this journal (Ostacher, 2014; Stein, 2016), and we write to highlight another dimension in this debate.

A growing divergence

Traditional diagnostic classifications and distinctions such as schizophrenia and bipolar disorder have limitations within current empirical research. This has led to the development of sub-categories and new classifications in the search for greater validity and utility of diagnoses. Validity is generally achieved when a concept is shown to be true and replicable, while utility can be met if a classification can inform treatment decisions, research targets, and describe the likelihood of relapse and functional impairment (Jablensky, 2016). Utility in the research domain does not, however, always translate to clinical utility.

For example, personality disorder diagnosis since DSM-III has been beset with issues of inflated comorbidities and reduced diagnostic specificity. The myriad of symptom profiles in individuals presenting with a personality disorder has led to more criteria to try and capture these, however, there remain individuals who do not meet these new thresholds and so receiving a ‘not otherwise specified’ diagnosis. Such changes to diagnostic boundaries by researchers have led to a reduced use of these benchmarks by clinicians due to unnecessary complexity and questions of usefulness for the clinical setting (Westen et al., 2010).

Ostacher (2014) commented on the growing divergence between diagnostic classifications for research and clinical use, but proposed that more specialised categories were acceptable in research settings, while clinical settings could use broader ones with better practicality. While this notion has veracity in the light of recent DSM-5 changes, it raises the concerning scenario that this divergence may intensify and exacerbate the already problematic discrepancies that Ostacher himself highlighted. The reduced translatability of research findings to clinical practice would further isolate the two areas. Stein (2016) cautioned against a fixation with fine-tuning nosology, noting the value that psychiatric classifications still play in the overall process of research and treatment.

Top–down versus bottom-up approaches

Traditional diagnostic classifications have also been criticised as being too utilitarian and problematic for practice. This is clearly demonstrated by the case of Schneiderian first-rank symptoms (FRS) that, while empirically developed, were given a degree of precedence in schizophrenia diagnosis. FRS were downgraded in importance in DSM-5, and subsequent evidence has supported their lack of diagnostic specificity for schizophrenia (Toh et al., 2016). Similarly, formal thought disorder (FTD) has been empirically shown to be varied in manifestation and mechanisms, but this is not reflected in its DSM description. The problems with diagnostic translation to clinical observations have undoubtedly contributed to the divide and have led to calls for newer approaches beyond just top-down diagnostics.

Cognitive neuropsychiatry (CNP) is one such empirically driven approach that transcends diagnostic classifications to explore potential cognitive explanations for psychiatric symptoms. This symptom-driven approach has greater empirical validity, particularly within schizophrenia where diverse symptom profiles in a single sample are often bemoaned as a research limitation. It also has relevance for understanding symptoms that appear across a range of diagnoses such as delusions in both schizophrenia and bipolar disorder. Clinical work could also benefit from CNP which would facilitate more tailored treatment plans for each patient depending on their individual symptom profile.

More recently, the move to reconceptualise research foci and bridge the gap with clinical utility is encapsulated in the Research Domain Criteria approach (RDoC). It provides both researchers and clinicians with an empirically based framework for understanding the processes that may be awry and underpin the myriad of symptoms seen in mental illness. RDoC and other novo-theoretical approaches like CNP are facilitating a synthesis between understanding and application in mental illness. That being said, the RDoC model has its own limitations. For psychiatry specifically, RDoC does not delineate phenomenological targets relating to mental illness. While a clearer understanding of brain circuitry is undoubtedly valuable, a funnel towards mental health benefit needs to be maintained. CNP is arguably more closely aligned with psychiatry in this regard.

Another cautionary note for researchers here relates to the multiple scales that are available to measure one construct (e.g. FTD, mood symptoms, etc.) and the importance of choosing the most appropriate ones. Maintaining consistency in empirical work, coupled with a clear focus on outcomes, is critical for facilitating effective and efficient translatability of their findings.

Towards a common goal

Jablensky (2016) has written cogently about the difference between validity and utility, and how a diagnostic category may have good utility but reduced validity. He goes on to describe validity in diagnosis as somewhat of an unattainable ideal and so a focus on utility is reasonable. Stein (2016) similarly argues that all diagnostic classifications have pros and cons, but the clinician should use all available information to make an informed decision for patient treatment plans. We concur with these conclusions in so far as they speak to a more cohesive and holistic approach to both research and clinical applications, where patient benefit is ultimately kept at the forefront.

We opine that research outputs should ultimately be translatable to clinical practice, just as clinical practice should always maintain a focus on patient benefit. The RDoC and CNP approaches provide feasible ways towards alleviating some of the constraints with traditional research diagnostics. In practice, clinical treatment plans tend to represent an amalgamation of both RDoC and DSM as seen in the growing use of alternative therapies such as cognitive remediation alongside traditional pharmaceutical treatments. Additionally, the potentially successful outcomes of RDoC could lead to stronger foundations for future revisions to clinical classifications.

Researchers should strive to work more closely alongside clinicians to ensure a smoother transition of empirical work to clinical situations. This has worked well in medical illnesses such as cancer. Outcomes for patients with a mental illness can be vastly improved if they were afforded continuous, timely and more coordinated care informed by the most up-to-date research and clinical knowledge. By keeping a common goal in sight, the future of research and clinical practice can move forth towards closer integration, or at least along parallel paths.