Biomarkers for site-specific response to neoadjuvant chemotherapy in epithelial ovarian cancer: relating MRI changes to tumour cell load and necrosis

BACKGROUND

Diffusion-weighted magnetic resonance imaging (DW-MRI) potentially interrogates site-specific response to neoadjuvant chemotherapy (NAC) in epithelial ovarian cancer (EOC).

METHODS

Participants with newly diagnosed EOC due for platinum-based chemotherapy and interval debulking surgery were recruited prospectively in a multicentre study (n = 47 participants). Apparent diffusion coefficient (ADC) and solid tumour volume (up to 10 lesions per participant) were obtained from DW-MRI before and after NAC (including double-baseline for repeatability assessment in n = 19). Anatomically matched lesions were analysed after surgical excision (65 lesions obtained from 25 participants). A trained algorithm determined tumour cell fraction, percentage tumour and percentage necrosis on histology. Whole-lesion post-NAC ADC and pre/post-NAC ADC changes were compared with histological metrics (residual tumour/necrosis) for each tumour site (ovarian, omental, peritoneal, lymph node).

RESULTS

Tumour volume reduced at all sites after NAC. ADC increased between pre- and post-NAC measurements. Post-NAC ADC correlated negatively with tumour cell fraction. Pre/post-NAC changes in ADC correlated positively with percentage necrosis. Significant correlations were driven by peritoneal lesions.

CONCLUSIONS

Following NAC in EOC, the ADC (measured using DW-MRI) increases differentially at disease sites despite similar tumour shrinkage, making its utility site-specific. After NAC, ADC correlates negatively with tumour cell fraction; change in ADC correlates positively with percentage necrosis.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT01505829.

Diffusion-weighted MRI in Advanced Epithelial Ovarian Cancer: Apparent Diffusion Coefficient as a Response Marker

Background Treatment of advanced epithelial ovarian cancer results in a relapse rate of 75%. Early markers of response would enable optimization of management and improved outcome in both primary and recurrent disease. Purpose To assess the apparent diffusion coefficient (ADC), derived from diffusion-weighted MRI, as an indicator of response, progression-free survival (PFS), and overall survival. Materials and Methods This prospective multicenter trial (from 2012-2016) recruited participants with stage III or IV ovarian, primary peritoneal, or fallopian tube cancer (newly diagnosed, cohort one; relapsed, cohort two) scheduled for platinum-based chemotherapy, with interval debulking surgery in cohort one. Cohort one underwent two baseline MRI examinations separated by 0-7 days to assess ADC repeatability; an additional MRI was performed after three treatment cycles. Cohort two underwent imaging at baseline and after one and three treatment cycles. ADC changes in responders and nonresponders were compared (Wilcoxon rank sum tests). PFS and overall survival were assessed by using a multivariable Cox model. Results A total of 125 participants (median age, 63.3 years [interquartile range, 57.0-70.7 years]; 125 women; cohort one, n = 47; cohort two, n = 78) were included. Baseline ADC (range, 77-258 × 10-5mm2s-1) was repeatable (upper and lower 95% limits of agreement of 12 × 10-5mm2s-1 [95% confidence interval {CI}: 6 × 10-5mm2s-1 to 18 × 10-5mm2s-1] and -15 × 10-5mm2s-1 [95% CI: -21 × 10-5mm2s-1 to -9 × 10-5mm2s-1]). ADC increased in 47% of cohort two after one treatment cycle, and in 58% and 53% of cohorts one and two, respectively, after three cycles. Percentage change from baseline differed between responders and nonresponders after three cycles (16.6% vs 3.9%; P = .02 [biochemical response definition]; 19.0% vs 6.2%; P = .04 [radiologic definition]). ADC increase after one cycle was associated with longer PFS in cohort two (adjusted hazard ratio, 0.86; 95% CI: 0.75, 0.98; P = .03). ADC change was not indicative of overall survival for either cohort. Conclusion After three cycles of platinum-based chemotherapy, apparent diffusion coefficient (ADC) changes are indicative of response. After one treatment cycle, increased ADC is indicative of improved progression-free survival in relapsed disease. Published under a CC BY 4.0 license. Online supplemental material is available for this article.

Feelings of worthlessness during a single complicated major depressive episode predict postremission suicide attempt

OBJECTIVE

To establish which symptoms of major depressive episode (MDE) predict postremission suicide attempts in complicated single-episode cases.

METHOD

Using the nationally representative two-wave National Epidemiologic Survey on Alcohol and Related Conditions data set, we identified wave 1 lifetime single-episode MDE cases in which the episode remitted by the beginning of the wave 2 three-year follow-up period (N = 2791). The analytic sample was further limited to 'complicated' cases (N = 1872) known to have elevated suicide attempt rates, defined as having two or more of the following: suicidal ideation, marked role impairment, feeling worthless, psychomotor retardation, and prolonged (>6 months) duration.

RESULTS

Logistic regression analyses showed that, after controlling for wave 1 suicide attempt which significantly predicted postremission suicide attempt (OR = 10.0), the additional complicated symptom 'feelings of worthlessness' during the wave 1 index episode significantly and very substantially predicted postremission suicide attempt (OR = 6.96). Neither wave 1 psychomotor retardation nor wave 1 suicidal ideation nor any of the other wave 1 depressive symptoms were significant predictors of wave 2 suicide attempt.

CONCLUSION

Among depressive symptoms during an MDE, feelings of worthlessness is the only significant indicator of elevated risk of suicide attempt after the episode has remitted, beyond previous suicide attempts.

Modelling DW-MRI data from primary and metastatic ovarian tumours

OBJECTIVES

To assess goodness-of-fit and repeatability of mono-exponential, stretched exponential and bi-exponential models of diffusion-weighted MRI (DW-MRI) data in primary and metastatic ovarian cancer.

METHODS

Thirty-nine primary and metastatic lesions from thirty-one patients with stage III or IV ovarian cancer were examined before and after chemotherapy using DW-MRI with ten diffusion-weightings. The data were fitted with (a) a mono-exponential model to give the apparent diffusion coefficient (ADC), (b) a stretched exponential model to give the distributed diffusion coefficient (DDC) and stretching parameter (α), and (c) a bi-exponential model to give the diffusion coefficient (D), perfusion fraction (f) and pseudodiffusion coefficient (D*).

RESULTS

Coefficients of variation, established from repeated baseline measurements, were: ADC 3.1%, DDC 4.3%, α 7.0%, D 13.2%, f 44.0%, D* 165.1%. The bi-exponential model was unsuitable in these data owing to poor repeatability. After excluding the bi-exponential model, analysis using Akaike Information Criteria showed that the stretched exponential model provided the better fit to the majority of pixels in 64% of lesions.

CONCLUSIONS

The stretched exponential model provides the optimal fit to DW-MRI data from ovarian, omental and peritoneal lesions and lymph nodes in pre-treatment and post-treatment measurements with good repeatability.

KEY POINTS

• DW-MRI data in ovarian cancer show deviation from mono-exponential behaviour • Parameters derived from the stretched exponential model showed good repeatability (CV 7%) • The bi-exponential model was unsuitable because of poor parameter repeatability • The stretched exponential model showed comparable repeatability to the mono-exponential model • The extra parameter (α) provides scope for investigation of heterogeneity or response.

Predictive validation of single-episode uncomplicated depression as a benign subtype of unipolar major depression

OBJECTIVE

To evaluate the predictive validity of a proposed benign major depressive disorder (MDD) subtype, single-episode 'uncomplicated MDD', defined as MDD that remits within 6 months and lacks severe impairment, psychotic ideation, suicidal ideation, psychomotor retardation, and feeling worthless.

METHOD

Using two-wave National Epidemiologic Survey on Alcohol and Related Conditions data, four groups differing in wave 1 lifetime MDD history (no history [n = 27 609]; single-episode uncomplicated [n = 418]; other single-episode [n = 1943]; multiple episode [n = 2473]) were evaluated for 3-year follow-up rates of major depressive episode (MDE), generalized anxiety disorder (GAD), and suicide attempt.

RESULTS

Follow-up rates for no-MDD-history, single-episode uncomplicated MDD, other single-episode MDD, and multiple-episode MDD, respectively, were depressive episode 6.1%, 6.9%, 19.5%, 27.1%; GAD 2.7%, 4.3%, 7.8%, 11.2%; and suicide attempt 0.3%, 0.1%, 0.8%, 1.7%. For all validators, 3-year rates for single-episode uncomplicated cases were not significantly different from no-MDD-history rates, but significantly lower than both single- and multiple-episode other-MDD rates. Mild MDD, defined by having only five or six symptoms, did not yield similarly benign results; logistic regression showed 'uncomplicated' provides incremental validity over 'mild' in explaining validator rates. Validator differences were not explainable by treatment-rate differences.

CONCLUSION

Single-episode uncomplicated MDD is a benign subtype lacking typical MDD negative sequelae. The planned DSM-5.1 revision should reinstitute an extended bereavement exclusion applied to all stressors.

Can the DSM's major depression bereavement exclusion be validly extended to other stressors? Evidence from the NCS

OBJECTIVE

To evaluate whether the DSM's distinction between uncomplicated (normal) vs. complicated (disordered) bereavement-related depressive episodes can be validly extended to non-bereavement stressor-related depression (SRD). Previous findings supporting the uncomplicated/complicated SRD distinction's discriminant validity were criticized as tautological because of definitional biases (e.g., 'uncomplicated' requires brief duration, yet duration was a validator). We tested whether uncomplicated/complicated SRD validator differences are tautological or real.

METHOD

Using National Comorbidity Survey data, we compared uncomplicated SRDs, complicated SRDs, and endogenous/psychotic MDD on levels of eight pathology validators. We identified definitional biases affecting six validators, and corrected them by deleting the biasing definitional components and recalculating validator levels.

RESULTS

After correction of biases, uncomplicated SRDs had significantly lower pathology levels than both complicated SRDs and endogenous/psychotic MDD on seven of eight validators, disconfirming the tautology hypothesis. Regression analysis revealed that 'uncomplicated' cannot be equated with 'mild'. Extending the 'uncomplicated' durational threshold from 2 to 6 months yielded equal or stronger discriminant validity, suggesting the arbitrariness of the current durational criterion.

CONCLUSION

Uncomplicated SRDs' lower pathology levels are because of real syndromal differences, not definitional tautologies. The uncomplicated/complicated distinction has discriminant validity when extended to non-bereavement SRDs as an indicator of normality vs. disorder.

HIBAG--HLA genotype imputation with attribute bagging

Genotyping of classical human leukocyte antigen (HLA) alleles is an essential tool in the analysis of diseases and adverse drug reactions with associations mapping to the major histocompatibility complex (MHC). However, deriving high-resolution HLA types subsequent to whole-genome single-nucleotide polymorphism (SNP) typing or sequencing is often cost prohibitive for large samples. An alternative approach takes advantage of the extended haplotype structure within the MHC to predict HLA alleles using dense SNP genotypes, such as those available from genome-wide SNP panels. Current methods for HLA imputation are difficult to apply or may require the user to have access to large training data sets with SNP and HLA types. We propose HIBAG, HLA Imputation using attribute BAGging, that makes predictions by averaging HLA-type posterior probabilities over an ensemble of classifiers built on bootstrap samples. We assess the performance of HIBAG using our study data (n=2668 subjects of European ancestry) as a training set and HLA data from the British 1958 birth cohort study (n≈1000 subjects) as independent validation samples. Prediction accuracies for HLA-A, B, C, DRB1 and DQB1 range from 92.2% to 98.1% using a set of SNP markers common to the Illumina 1M Duo, OmniQuad, OmniExpress, 660K and 550K platforms. HIBAG performed well compared with the other two leading methods, HLA*IMP and BEAGLE. This method is implemented in a freely available HIBAG R package that includes pre-fit classifiers for European, Asian, Hispanic and African ancestries, providing a readily available imputation approach without the need to have access to large training data sets.

Normal vs. disordered bereavement-related depression: are the differences real or tautological?

OBJECTIVE

To evaluate whether the DSM distinction between uncomplicated (normal) and complicated (disordered) bereavement-related depression (BRD) has discriminant validity on a range of pathology indicators. The DSM's major depression bereavement exclusion (BE) excludes BRDs from diagnosis when they are uncomplicated (defined by brief duration, non-severe impairment, and lack of certain pathosuggestive symptoms) but classifies all other ("complicated") BRDs as major depression. A previous report seemed to support the uncomplicated/complicated distinction's discriminant validity. However, those arguing for eliminating the BE from DSM-5 dismiss the findings as 'tautological,' attributing the validator differences to definitional biases (e.g. 'uncomplicated' requires 'no suicidal ideation,' yet 'lifetime suicide attempt' was a validator). This study empirically tests whether the uncomplicated/complicated differences are real or tautological.

METHOD

Using National Comorbidity Survey data, confounds between definitional criteria for 'uncomplicated' and pathology validators were identified and corrected by deleting the biasing criteria and recalculating the corresponding validator's outcome.

RESULTS

Six validators (interference with life, suicide attempt, melancholic depression, duration, hospitalization, and number of symptoms) were reanalyzed using unbiased definitions for 'uncomplicated.' All still yielded significantly lower pathology levels for uncomplicated BRDs, disconfirming the 'tautology' hypothesis. Regression analysis revealed that 'uncomplicated' offered incremental validity over severity alone in predicting pathology, so 'uncomplicated' cannot be equated with 'mild.'

CONCLUSION

Uncomplicated BRDs' lower pathology validator levels are because of real syndromal differences, not definitional tautologies, supporting the BE's validity.

Relation between duration and severity in bereavement-related depression

OBJECTIVE

Prolonged duration is commonly used as an indicator that bereavement-related depression (BRD) is pathological. DSM-IV replaced the traditional 1-year pathology cut-point by a 2-month cut-point. Yet, little evidence exists regarding the validity of these cut-points in indicating increased BRD severity. This study evaluated the validity of the 2-month and 1-year cut-points in differentiating less severe from more severe BRDs in a nationally representative U.S. sample.

METHOD

National Comorbidity Survey respondents with BRD's (n = 152) lasting 0-8, 9-52 and >52 weeks were evaluated for depression severity using six severity indicators. Cut-point validity was established by discontinuities in severity levels between durations below and above the cut-point.

RESULTS

Bereavement-related depressions of >52-week duration were significantly higher than 9- to 52-week BRDs on four of six severity indicators and on a cumulative overall severity measure of mean number of severity indicators per person, whereas ≤8-week and 9- to 52-week durational categories differed on one severity indicator and not on overall severity. Additional analyses using durations 0-12, 13-26, 27-52 and >52 weeks suggested that alternative <52-week cut-points also lack validity.

CONCLUSION

The traditional 1-year cut-point validly identifies increasing BRD severity; DSM's 2-month cut-point does not. Duration does not indicate increasing BRD severity before 1 year. Research using the 2-month cut-point may yield misleading results.

CooB is required for assembly but not transport of CS1 pilin

CS1 pili are filamentous proteinaceous appendages found on many enterotoxigenic Escherichia coli (ETEC) strains isolated from human diarrhoeal disease. They are thought to effect colonization of the upper intestine by facilitating binding to human ileal epithelial cells. We have identified a gene, cooB, which lies directly upstream of cooA, the gene that encodes the major structural CS1 protein. When translated in vitro, the protein product of cooB migrates in sodium dodecyl sulphate/polyacrylamide gel with an apparent molecular mass of 26 kDa, which is consistent with that predicted from its DNA sequence. We constructed a mutant allele (cooB-1) by insertion of the omega fragment, which inhibits transcription and translation, into the cooB gene in vitro. In a derivative of an ETEC strain with the cooB-1 mutation (JEF100) and a plasmid that encodes Rns (pEU2030), the positive regulator required for CS1 expression, no cooB and a greatly reduced level of cooA product was detectable in total cell extracts. The reduction of cooA in this strain appears to result from polarity of the cooB mutation because introduction of the wild-type cooA gene in trans causes production of CooA protein, which is found in cell pellet extracts, in extracts containing only surface proteins and in the culture supernatant. Therefore, in the absence of CooB, CooA is stable and it is transported through both inner and outer membranes. However, the cooB-1 strain with cooA in trans does not cause haemagglutination of bovine erythrocytes (the model system used to assay adherence mediated by coli surface antigen 1 (CS1) pili).(ABSTRACT TRUNCATED AT 250 WORDS)

The myth of DSM's invention of new categories of disorder: Houts's diagnostic discontinuity thesis disconfirmed

Houts (2001) argues that increases in DSM diagnostic categories are due to the invention of new disorders that are discontinuous with old conceptions of disorder and would not have been previously diagnosed. He maintains that DSM category increases are not comparable in nature to ICD category increases, which are mainly refinements of recognized disorders. I survey categories of disorder introduced after DSM-II and assess whether they are discontinuous with old concepts and categories of disorder. Candidate categories are identified from: Houts and Follette (1998), Mentalism, mechanisms, and medical analogues: Reply to Wakefield. Journal of Consulting and Clinical Psychology; Kutchins and Kirk (1997) Making us crazy: DSM: The psychiatric bible and the creation of mental disorders. New York: Free Press; and my own list. The result is that virtually none of the candidate categories are invented, discontinuous categories. In almost every case, the newly labeled conditions were considered disorders at the time of DSM-II and would have been diagnosed under DSM-II categories. I also reexamine DSM-IV sleep disorder categories, which Houts claims are discontinuous with past diagnostic conceptions. The result is that all DSM-IV sleep disorders were recognized as disorders at the time of DSM-II, and most were recognized as mental disorders. I conclude that DSM category increases are comparable in nature to ICD category increases, and that the invention-of-disorder account cannot explain the vast majority of such increases.

Evolutionary history versus current causal role in the definition of disorder: reply to McNally

The harmful dysfunction (HD) analysis (Wakefield, American Psychologist 47 (1992a) 373) asserts that "disorder" means "harmful dysfunction", where "harm" is a value concept anchored in social values and "dysfunction" is a factual concept referring to failure of a mechanism to perform a natural function. Additionally, the HD analysis claims that a mechanism's natural functions are its naturally selected effects. McNally (Behaviour Research and Therapy (2000) pp. 309-314) argues to the contrary that "dysfunction" is a value concept referring to negative failures of function, that "function" refers to current causal roles and not evolutionarily designed causal roles, and that "disorder" consequently means "harmful failure of a mechanism to perform a valued current causal role." I reply by showing that McNally's proposals lack the HD analysis's power to explain common judgments about function, dysfunction, and disorder. "Dysfunction" cannot be a negative value concept because many dysfunctions are positive or neutral; "function" cannot refer to current causal roles because many current causal roles are not functions and some functions are not current causal roles; and "disorder" cannot refer to harmful failures of current causal roles because that definition allows almost any negative condition whatever to be a disorder and thus fails to explain the distinctions we make between disorder and non-disorder.

The analyst's knowledge and authority: a critique of the "new view" in psychoanalysis

A critical assessment is presented of positions recently taken by Mitchell and Renik, who are taken as representatives of a "new view" in psychoanalysis. One article by Mitchell and two by Renik are examined as paradigmatic of certain ways of construing the nature of mind, the analyst's knowledge and authority, and the analytic process that are unduly influenced by the postmodern turn in psychoanalysis. Although "new view" theorists have made valid criticisms of traditional psychoanalytic theory and practice, they wind up taking untenable positions. Specifically called into question are their views on the relation between language and interpretation, on the one hand, and the mental contents of the patient on the other. A disjunction is noted between their discussion of clinical material and their conceptual stance, and their idiosyncratic redefinitions of truth and objectivity are criticized. Finally, a "humble realism" is suggested as the most appropriate philosophical position for psychoanalysts to adopt.

Statistical issues in the analysis of disease mapping data

In this paper we discuss a number of issues that are pertinent to the analysis of disease mapping data. As an illustrative example we consider the mapping of larynx cancer across electoral wards in the North West Thames region of the U.K. Bayesian hierarchical models are now frequently employed to carry out such mapping. In a typical situation, a three-stage hierarchical model is specified in which the data are modelled as a function of area-specific relative risks at stage one; the collection of relative risks across the study region are modelled at stage two; and at stage three prior distributions are assigned to parameters of the stage two distribution. Such models allow area-specific disease relative risks to be 'smoothed' towards global and/or local mean levels across the study region. However, these models contain many structural and functional assumptions at different levels of the hierarchy; we aim to discuss some of these assumptions and illustrate their sensitivity. When relative risks are the endpoint of interest, it is common practice to assume that, for each of the age-sex strata of a particular area, there is a common multiplier (the relative risk) acting upon each of the stratum-specific risks in that area; we will examine this proportionality assumption. We also consider the choices of models and priors at stages two and three of the hierarchy, the effect of outlying areas, and an assessment of the level of smoothing that is being carried out. For inference, we concentrate on the description of the spatial variability in relative risks and on the association between the relative risks of larynx cancer and an area-level measure of socio-economic status.

Point-source modelling using matched case-control data

We describe an extension to matched case-control studies of the parametric modelling framework developed by Diggle (1990) and Diggle and Rowlingson (1994) to investigate raised risk around putative sources of environmental pollution. We use a conditional likelihood approach for the family of risk functions considered in Diggle and Rowlingson (1994). We show that the likelihood surface that results from these models may be highly irregular, and provide a Bayesian analysis in which we investigate the posterior distribution using Markov chain Monte Carlo. An analysis of one-one matched data that were collected to investigate the relationship between respiratory disease and distance to roads in East London is presented.

Mental disorder as a black box essentialist concept

This is a reply to commentaries on the target article (J. C. Wakefield, 1999) on the evolutionary foundations of the concept of mental disorder in defense of the harmful dysfunction analysis (HDA) of disorder. The author argues that the HDA is adequate to explain disorder and nondisorder judgments and is not disconfirmed by any of the claimed counterexamples put forward by the commentators; the commentators' proposed alternatives to the HDA are inadequate to explain disorder and nondisorder judgments; and the concept of natural function is a factual, scientific concept, contrary to K. W. M. Fulford's (1999) claim that it is inherently evaluative. The foundations of the HDA are clarified by providing a black box essentialist analysis (H. Putnam, 1975; J. C. Wakefield, 1997, in press) of the concept of natural function that underlies the concept of disorder.

Evolutionary versus prototype analyses of the concept of disorder

The harmful dysfunction (HD) analysis of the concept of disorder (J. C. Wakefield, 1992a) holds that disorders are harmful failures of internal mechanisms to perform their naturally selected functions. S. O. Lilienfeld and L. Marino (1995) proposed instead that disorder is a Roschian prototype concept without defining properties. Against the HD analysis, they argued that many disorders are not failures of naturally selected functions because they are either designed reactions (e.g., fever) or failures of functions that are not naturally selected (e.g., reading disorder). The HD analysis is defended here against these and other objections and compared with the Roschian account. It is argued that the objections are based on conceptual confusions and can be turned around to provide strong new support for the HD analysis. A series of conceptual experiments demonstrates the superior explanatory power of the HD analysis and disconfirms the Roschian account.

DSM-IV diagnostic criterion for clinical significance: does it help solve the false positives problem?

OBJECTIVE

A major change in DSM-IV is the inclusion in almost one-half of the diagnostic criteria sets of a clinical significance criterion, which requires that symptoms cause "clinically significant distress or impairment in social, occupational, or other important areas of functioning." In response to concerns that the DSM criteria are overly inclusive, the clinical significance criterion attempts to minimize false positive diagnoses in situations in which the symptom criteria do not necessarily indicate pathology. This article examines whether the clinical significance criterion achieves its purpose and considers its broader impact on diagnostic validity.

METHOD

The effect of the clinical significance criterion on the diagnostic validity of DSM-IV criteria for a wide range of disorders was examined.

RESULTS

For many diagnoses to which the clinical significance criterion was added, the symptom criteria are inherently associated with significant impairment, so the clinical significance criterion is redundant and therefore does not affect caseness. For some diagnoses, the clinical significance criterion is potentially helpful in eliminating false positives by elevating the level of required distress. However, there may be advantages to obtaining the same results by modifying some of the symptom criteria. Often the clinical significance criterion has led to the possibility of false negative diagnoses.

CONCLUSIONS

In the process of revising DSM-IV, the generic use of the clinical significance criterion should be reconsidered. For each DSM diagnosis, it should be determined whether there is a need to raise the threshold of any of the existing symptom criteria or to add a criterion that excludes normal reactions to psychosocial stress.

Philosophy of science and the progressiveness of the DSM's theory-neutral nosology: response to Follette and Houts, Part 1

Follette and Houts [Follette, W. C., Houts, A. C. (1996). Models of scientific progress and the role of theory in taxonomy development: a case study of the DSM. Journal of Consulting and Clinical Psychology, 64, 1120-1132] argue on philosophy-of-science grounds that the DSM's theory-neutral nosology is scientifically unprogressive because of its growing number of categories and lack of a unifying explanatory theory. They suggested replacing the DSM by competing theory-laden diagnostic manuals. I argue: (1) the ways things can go wrong with the mind are inherently diverse, so a unified theory of mental disorders is unlikely; (2) the claim that an increase in categories is inconsistent with scientific progress is empirically false; (3) the claim that the DSM's new categories expand the domain of disorder is largely false; (4) progress in a theoretically fragmented field requires a shared theory-neutrally defined domain; (5) theory-neutral diagnosis and integration of etiological theories is preferable for now to competition among theory-based diagnostic manuals; (6) philosophy of science supports use of a theory-neutral nosology for now.

The concept of disorder as a foundation for the DSM's theory-neutral nosology: response to Follette and Houts, Part 2

Follette and Houts [Follette, W. C., Houts, A. C. (1996). Models of scientific progress and the role of theory in taxonomy development: a case study of the DSM. Journal of Consulting and Clinical Psychology, 64, 1120-1132] argue that 'mental disorder' and 'function' are value concepts that offer no scientific basis for the DSM's theory-neutral nosology or for distinguishing disorders from other behavioral problems. They also claim that the DSM presupposes a biological theory of etiology, thus is not really theory-neutral. They recommend replacing the DSM by theory-laden diagnostic manuals. I argue: (1) DSM criteria do not imply a biological model of disorder, (2) 'mental disorder' and 'function' have scientific content that allows one to distinguish disorder from nondisorder, (3) the evolutionary 'harmful dysfunction' analysis of disorder [Wakefield, J. C. (1992a). The concept of mental disorder: on the boundary between biological facts and social values. American Psychologist, 47, 373-388] coherently demarcates disorder from nondisorder, (4) the proposed behaviorist alternative to the DSM illustrated by the articles in Follette's special section [Follette, W. C. (Ed.) (1996a). Special section on the development of theoretically coherent alternatives to the DSM system. Journal of Consulting and Clinical Psychology, 64, 1117-1201] is incoherent because it does not distinguish disorder from nondisorder.

The Bayesian analysis of a pivotal pharmacokinetic study

The aim of this paper is to carry out a detailed Bayesian population pharmacokinetic analysis of a three-period cross-over study of the drug fluticasone propionate carried out in 12 healthy male volunteers. The study was carried out to characterize the pharmacokinetics of the drug, in particular to investigate dose proportionality. We examine the appropriateness of modelling assumptions via a variety of diagnostic techniques. We also examine the effect of deleting time points at which the concentration was recorded as below the limit of quantification, as opposed to including these points as censored observations. We assess dose proportionality before carrying out a final combined analysis of data from all three doses.

Mental disorder as a black box essentialist concept

This is a reply to commentaries on the target article (J. C. Wakefield, 1999) on the evolutionary foundations of the concept of mental disorder in defense of the harmful dysfunction analysis (HDA) of disorder. The author argues that the HDA is adequate to explain disorder and nondisorder judgments and is not disconfirmed by any of the claimed counterexamples put forward by the commentators; the commentators' proposed alternatives to the HDA are inadequate to explain disorder and nondisorder judgments; and the concept of natural function is a factual, scientific concept, contrary to K. W. M. Fulford's (1999) claim that it is inherently evaluative. The foundations of the HDA are clarified by providing a black box essentialist analysis (H. Putnam, 1975; J. C. Wakefield, 1997, in press) of the concept of natural function that underlies the concept of disorder.

Evolutionary versus prototype analyses of the concept of disorder

The harmful dysfunction (HD) analysis of the concept of disorder (J. C. Wakefield, 1992a) holds that disorders are harmful failures of internal mechanisms to perform their naturally selected functions. S. O. Lilienfeld and L. Marino (1995) proposed instead that disorder is a Roschian prototype concept without defining properties. Against the HD analysis, they argued that many disorders are not failures of naturally selected functions because they are either designed reactions (e.g., fever) or failures of functions that are not naturally selected (e.g., reading disorder). The HD analysis is defended here against these and other objections and compared with the Roschian account. It is argued that the objections are based on conceptual confusions and can be turned around to provide strong new support for the HD analysis. A series of conceptual experiments demonstrates the superior explanatory power of the HD analysis and disconfirms the Roschian account.

The DSM's theory-neutral nosology is scientifically progressive: response to Follette and Houts (1996)

W. C. Follette and A. C. Houts (1996) argued on philosophy-of-science grounds that the Diagnostic and Statistical Manual of Mental Disorders (DSM) is scientifically unprogressive and should be replaced by competing theory-laden manuals. The author responds to their various arguments as follows: (a) The ways things can go wrong with the mind are inherently diverse, so failure to reduce the DSM's categories to 1 parsimonious theory is not necessarily scientifically unprogressive; (b) it is empirically untrue that growth in the number of a taxonomy's categories is inconsistent with scientific progress; (c) progress in theoretically fragmented fields requires shared theory-neutral categories, not theory-laden definitions of basic concepts; (d) at present in the mental health field, theoretical integration is scientifically more progressive than competition, and integration is promoted by the DSM's theory-neutral nosology; and (e) Follette and Houts's proposed behaviorist alternative to the DSM is incoherent.

The DSM's theory-neutral nosology is scientifically progressive: response to Follette and Houts (1996)

W. C. Follette and A. C. Houts (1996) argued on philosophy-of-science grounds that the Diagnostic and Statistical Manual of Mental Disorders (DSM) is scientifically unprogressive and should be replaced by competing theory-laden manuals. The author responds to their various arguments as follows: (a) The ways things can go wrong with the mind are inherently diverse, so failure to reduce the DSM's categories to 1 parsimonious theory is not necessarily scientifically unprogressive; (b) it is empirically untrue that growth in the number of a taxonomy's categories is inconsistent with scientific progress; (c) progress in theoretically fragmented fields requires shared theory-neutral categories, not theory-laden definitions of basic concepts; (d) at present in the mental health field, theoretical integration is scientifically more progressive than competition, and integration is promoted by the DSM's theory-neutral nosology; and (e) Follette and Houts's proposed behaviorist alternative to the DSM is incoherent.

Adaptations, exaptations, and spandrels

Adaptation and natural selection are central concepts in the emerging science of evolutionary psychology. Natural selection is the only known causal process capable of producing complex functional organic mechanisms. These adaptations, along with their incidental by-products and a residue of noise, comprise all forms of life. Recently, S. J. Gould (1991) proposed that exaptations and spandrels may be more important than adaptations for evolutionary psychology. These refer to features that did not originally arise for their current use but rather were co-opted for new purposes. He suggested that many important phenomena--such as art, language, commerce, and war--although evolutionary in origin, are incidental spandrels of the large human brain. The authors outline the conceptual and evidentiary standards that apply to adaptations, exaptations, and spandrels and discuss the relative utility of these concepts for psychological science.

Adaptations, exaptations, and spandrels

Adaptation and natural selection are central concepts in the emerging science of evolutionary psychology. Natural selection is the only known causal process capable of producing complex functional organic mechanisms. These adaptations, along with their incidental by-products and a residue of noise, comprise all forms of life. Recently, S. J. Gould (1991) proposed that exaptations and spandrels may be more important than adaptations for evolutionary psychology. These refer to features that did not originally arise for their current use but rather were co-opted for new purposes. He suggested that many important phenomena--such as art, language, commerce, and war--although evolutionary in origin, are incidental spandrels of the large human brain. The authors outline the conceptual and evidentiary standards that apply to adaptations, exaptations, and spandrels and discuss the relative utility of these concepts for psychological science.

Diagnosing DSM-IV--Part I: DSM-IV and the concept of disorder

In this first article in a two-article series, I diagnose' a problem with DSM-IV, specifically, the overinclusiveness of its diagnostic criteria. Using the harmful dysfunction analysis of the concept of disorder (Wakefield, 1992a, American Psychologist, 47, 373-388) as a framework, I argue that DSM-IV criteria for many diagnostic categories fail to satisfy the analysis' dysfunction' requirement, that is, the criteria do not distinguish harmful conditions due to internal dysfunctions from harmful conditions that are nondisordered 'problems in living'. The overinclusiveness problem, I suggest, can be partly dealt with by giving up purely symptomatic criteria and contextualizing diagnosis to take into account the relationship between triggering causes and resulting symptoms. In Part II (Wakefield, 1997, Behaviour Research and Therapy, 35, 651-665, I examine Eysenck's (1986, Contemporary directions in psychopathology: Toward the DSM-IV) proposal for a dimensional diagnostic system to supplant DSM-IV.

Diagnosing DSM-IV--Part II: Eysenck (1986) and the essentialist fallacy

In Part I (Wakefield, 1997, Behaviour Research and Therapy, 35, 633-649) of this two-article series, I used the harmful dysfunction analysis of the concept of disorder (Wakefield, 1992a, American Psychologist, 47, 373-388) to 'diagnose' a problem with DSM-IV. I argued that DSM-IV diagnostic criteria often violate the 'dysfunction' requirement by invalidity classifying harms not caused by dysfunctions as disorders. In Part II, I examine Eysenck's (Eysenck, 1986, Contemporary directions in psychopathology: Toward the DSM-IV) argument that DSM commits a 'categorical fallacy' and should be replaced by dimensional diagnoses based on Eysenckian personality traits. I argue that Eysenck's proposed diagnostic criteria violate the 'harm' requirement by invalidly classifying symptomless conditions as disorders. Eysenck commits an 'essentialist fallacy'; he misconstrues 'disorder' as an essentialist theoretical concept when in fact it is a hybrid theoretical-practical or 'cause-effect' concept. He thus ignores the harmful effects essential to disorder that are captured in DSM's symptom-based categories.

When is development disordered? Developmental psychopathology and the harmful dysfunction analysis of mental disorder

One goal of developmental psychopathology is to understand the origins and course of mental disorders. I argue that pursuit of this goal requires a valid conceptual understanding of disorder and that this understanding can be provided by the "harmful dysfunction" analysis of the concept of disorder. The harmful dysfunction analysis holds that a disorder is a condition that is both harmful according to social values and caused by an internal dysfunction, that is, by a failure of an internal mechanism to perform a function for which it was naturally selected. This analysis explains why many of the distinctive features of developmental psychopathology are appropriate to the study of disorder. It is argued that the harmful dysfunction analysis is a necessary supplement to other proposed criteria for disorder, such as developmental deviation or predictive validity.

Modeling of trough plasma bismuth concentrations

Disposition pharmacokinetics of bismuth following oral dosing of ranitidine bismuth citrate are complicated and variable. An analysis of data from healthy volunteers suggests a model with three disposition compartments and first-order absorption. Patient data are pooled from 10 separate studies and consist of 1140 trough concentrations measured in 802 patients following dosing of 2 to 12 weeks duration. There are therefore insufficient data to obtain reliable parameter estimates for the full model and we use instead a much reduced model and an informative prior based on the volunteer data. Individual parameter estimates from this model can then be used to establish covariate relationships. Trough concentrations were influenced by the coadministration of clarithromycin and by creatinine clearance. A simulation study was carried out to check the validity of the estimates obtained from the reduced model. We carry out analysis via Bayesian sampling-based techniques. Throughout, we use predictive distributions for both diagnostic and inference purposes. In particular, we determine predicted distributions for the Cmax, Cmin and AUC characteristics of new individuals.

A comparison of a Bayesian population method with two methods as implemented in commercially available software

In this paper we describe and discuss three specific estimation procedures that are available within commercially available population software packages. The first version of NONMEM (l) was released in 1979 and later versions are the standard analysis tools in both industry and academia. Recently, two commercially available pieces of software have become available. PPHARM was released during 1994 and POPKAN was released in 1995. We provide descriptions and critique the FOCE method within NONMEM, the two-step algorithm within PPHARM and the Markov chain Monte Carlo method that is utilized by POPKAN. We use simulated data generated from a monoexponential model to evaluate the parameter estimation capabilities of these methods within the three software tools. In particular we investigate the effect on parameter estimation of increasing both interindividual and intraindividual variability.

CooC and CooD are required for assembly of CS1 pili

Many strains of enterotoxigenic Escherichia coli (ETEC) isolated from patients with diarrhoeal disease exhibit CS1 pili on their surfaces. These appendages, which are thought to be important for colonization of the upper intestine, are composed largely of multiple identical protein subunits encoded by cooA. We have sequenced the DNA directly downstream of cooA and identified two open reading frames, cooC and cooD, transcribed in the same direction as cooB and cooA. Following cooD is DNA homologous to an insertion sequence, so cooB, A, C and D appear to encode all the information needed for E. coli K-12 to synthesize CS1 pili. Complementation analysis of mutants cloned in E. coli K-12 and constructed in an ETEC-derived strain indicates that cooC and cooD are not required for stability of the major CS1 pilin protein or for its transport to the periplasm, but, like cooB, both are needed for assembly of cooA into pili.

Limits of operationalization: a critique of Spitzer and Endicott's (1978) proposed operational criteria for mental disorder

Spitzer and Endicott (1978) proposed an operational definition of mental disorder that is a more rigorous version of the brief definitions that appeared in the 3rd and revised 3rd editions of the Diagnostic and Statistical Manual of Mental Disorders. The heart of their proposal is a translation of the concept of dysfunction into operational terms. I argue that their definition fails to capture the concept of dysfunction and is subject to many counterexamples. I use my harmful dysfunction account of disorder (Wakefield, 1992a, 1992b), which interprets dysfunction in evolutionary terms, to explain both the appeal and the problems of Spitzer and Endicott's definition and to provide support for the harmful dysfunction view. I conclude that the failure of Spitzer and Endicott's sophisticated attempt at operationalization indicates that nonoperational definitions that use functional concepts must play a role in formulating valid diagnostic criteria.

Limits of operationalization: a critique of Spitzer and Endicott's (1978) proposed operational criteria for mental disorder

Spitzer and Endicott (1978) proposed an operational definition of mental disorder that is a more rigorous version of the brief definitions that appeared in the 3rd and revised 3rd editions of the Diagnostic and Statistical Manual of Mental Disorders. The heart of their proposal is a translation of the concept of dysfunction into operational terms. I argue that their definition fails to capture the concept of dysfunction and is subject to many counterexamples. I use my harmful dysfunction account of disorder (Wakefield, 1992a, 1992b), which interprets dysfunction in evolutionary terms, to explain both the appeal and the problems of Spitzer and Endicott's definition and to provide support for the harmful dysfunction view. I conclude that the failure of Spitzer and Endicott's sophisticated attempt at operationalization indicates that nonoperational definitions that use functional concepts must play a role in formulating valid diagnostic criteria.

Disorder as harmful dysfunction: a conceptual critique of DSM-III-R's definition of mental disorder

The Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.; DSM-III-R) operationally defines disorder essentially as "statistically unexpectable distress or disability." This definition is an attempt to operationalize 2 basic principles: that a disorder is harmful and that a disorder is a dysfunction (i.e., an inability of some internal mechanism to perform its natural function). However, the definition fails to capture the idea of "dysfunction" and so fails to validly distinguish disorders from nondisorders, leading to invalidities in many of DSM-III-R's specific diagnostic criteria. These problems with validity are traced to DSM-III-R's strategies for increasing reliability.

The concept of mental disorder. On the boundary between biological facts and social values

Although the concept of mental disorder is fundamental to theory and practice in the mental health field, no agreed on and adequate analysis of this concept currently exists. I argue that a disorder is a harmful dysfunction, wherein harmful is a value term based on social norms, and dysfunction is a scientific term referring to the failure of a mental mechanism to perform a natural function for which it was designed by evolution. Thus, the concept of disorder combines value and scientific components. Six other accounts of disorder are evaluated, including the skeptical antipsychiatric view, the value approach, disorder as whatever professionals treat, two scientific approaches (statistical deviance and biological disadvantage), and the operational definition of disorder as "unexpectable distress or disability" in the revised third edition of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1987). The harmful dysfunction analysis is shown to avoid the problems while preserving the insights of these other approaches.

The concept of mental disorder: On the boundary between biological facts and social values

Although the concept of mental disorder is fundamental to theory and practice in the mental health field, no agreed on and adequate analysis of this concept currently exists. I argue that a disorder is a harmful dysfunction, wherein harmful is a value term based on social norms, and dysfunction is a scientific term referring to the failure of a mental mechanism to perform a natural function for which it was designed by evolution. Thus, the concept of disorder combines value and scientific components. Six other accounts of disorder are evaluated, including the skeptical antipsychiatric view, the value approach, disorder as whatever professionals treat, two scientific approaches (statistical deviance and biological disadvantage), and the operational definition of disorder as "unexpectable distress or disability" in the revised third edition of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1987). The harmful dysfunction analysis is shown to avoid the problems while preserving the insights of these other approaches.

Hierarchical models for multicentre binary response studies

A three-stage hierarchical model is proposed for two treatment, binary response studies conducted in a number of centres. The approach adopted is Bayesian. Marginal densities for second stage parameters are shown to provide useful summaries both of comparative efficacy and of the heterogeneity of treatment effects across centres. Sensitivity studies of model assumptions are illustrated.