Dimensions will be assessed on a 0-4 scale cross-sectionally, with severity assessment based on past month. There are distinct psychopathological domains in psychotic illnesses (most clearly noted in schizophrenia) with distinctive patterns of treatment-response, prognostic implications, and course. The relative severity of symptoms across these domains varies across the course of illness and among patients. This is a major change that will potentially be of great clinical value and will also be of additional research utility.

 

	Hallucinations	Delusions	Disorganization	Abnormal Psychomotor Behavior	Restricted Emotional Expression	Avolition	Impaired Cognition	Depression	Mania
0	Not Present	Not Present	Not Present	Not Present	Not Present	Not Present	Not Present	Not Present	Not Present
1	Equivocal (severity or duration not sufficient to be considered psychosis)	Equivocal (severity or duration not sufficient to be considered psychosis)	Equivocal (severity or duration not sufficient to be considered disorganization)	Equivocal (severity or duration not sufficient to be considered abnormal psychomotor behavior)	Equivocal decrease in facial expressivity, prosody, or gestures	Equivocal decrease in self-initiated behavior	Equivocal (cognitive function not clearly outside the range expected for age or SES, i.e., within 1 SD of mean)	Equivocal (some depressed mood, but insufficient symptoms, duration or severity to meet diagnostic criteria)	Equivocal (some inflated or irritable mood, but insufficient symptoms, duration, or severity to meet diagnostic criteria)
2	Present, but mild (little pressure to act upon voices, not very bothered by voices)	Present, but mild (delusions are not bizarre, or little pressure to act upon delusional beliefs, not very bothered by beliefs)	Present, but mild (some difficulty following speech and/or occasional bizarre behavior)	Present, but mild (occasional abnormal motor behavior)	Present, but mild decrease in facial expressivity, prosody, or gestures	Present, but mild in self-initiated behavior	Present, but mild (some reduction in cognitive function below expected for age and SES, b/w 1 and 2 SD from mean)	Present, but mild (meets criteria for Major Depression, with minimum number of symptoms, duration, and severity)	Present, but mild (meets criteria for Mania with minimum number of symptoms, duration, and severity)
3	Present and moderate (some pressure to respond to voices, or is somewhat bothered by voices)	Present and moderate (some pressure to act upon beliefs, or is somewhat bothered by beliefs)	Present and moderate (speech often difficult to follow and/or frequent bizarre behavior)	Present and moderate (frequent abnormal motor behavior)	Present and moderate decrease in facial expressivity, prosody, or gestures	Present and moderate in self-initiated behavior	Present and moderate (clear reduction in cognitive function below expected for age and SES, b/w 2 and 3 SD from mean)	Present and moderate (meets criteria for Major Depression with somewhat more than the minimum number of symptoms, duration, and/or severity	Present and moderate (meets criteria for Mania with somewhat more than the minimum number of symptoms duration, and/or severity)
4	Present and severe (severe pressure to respond to voices, or is very bothered by voices)	Present and severe (severe pressure to act upon beliefs, or is very bothered by beliefs)	Present and severe (speech almost impossible to follow and/or behavior almost always bizarre)	Present and severe (abnormal motor behavior almost constant)	Present and severe decrease in facial expressivity, prosody, or gestures	Present and severe in self-initiated behavior	Present and severe (severe reduction in cognitive function below expected for age and SES, > 3SD from mean)	Present and severe (meets criteria for Major Depression with many more than the minimum number of symptoms and/or severity)	Present and severe (meets criteria for Mania with many more than the minimum umber of symptoms and/or severity)

 

Logic and Justification for Dimensional Assessment of Symptoms and

Related Clinical Phenomena in Psychosis.

Work on the causes and treatment of schizophrenia and other psychotic disorders has long recognized the heterogeneity of the symptoms that can be displayed by individuals with psychosis.  In addition, researchers have increasingly emphasized the ways in which the severity of different symptoms of this illness can vary across individuals, and have provided evidence that the severity of such symptoms can predict other important aspects of the illness, such as the degree of cognitive and/or neurobiological deficits (e.g., Barch et al. 2003; Barch et al. 2004; Delawalla et al. 2006; Kerns and Berenbaum 2002; Perlstein et al. 2003; Strauss et al. 1993).  Further, research has increasingly emphasized that the boundaries between nosological entities may not be as categorical as suggested by individuals such as Kraepelin (Kraepelin 1971), and putative comorbidity of various disorders may reflect impairments in common dimensions of genetic variation, human behavior and neurobiological function (Owen et al. 2007). As such, it is important to explicitly include dimensional assessments of the core symptoms of psychotic disorders to help us identify this important variability.  Thus, we propose to include dimensional assessments of all of the symptoms included as diagnostic indicators in Criterion A of the diagnostic criteria for schizophrenia.  This includes hallucinations, delusions, disorganization, abnormal motor behavior, restricted emotional expression, and avolition.  Each of these symptoms will be rated for their current severity (most severe in the past month) on a five-point scale ranging from 0 (Not Present) to 5 (Present and Severe).  A score of 2 or higher will be considered sufficient severity to fulfill a Criterion A diagnostic Indicator for Schizophrenia.  We believe that including these dimensional assessments will help diagnosticians make reliable decisions about the presence or absence of diagnostic phenomena and that it will help clinicians attend to the clinically meaningful variation in the severity of these symptoms, which will help with treatment planning, prognostic decision making, and research on pathophysiological mechanisms. 

Hallucinations and Delusions

One might question whether we could collapse some of the symptoms in to a single dimension.  For example, both hallucinations and delusions are considered to be evidence of impaired reality testing, and in theory we could collapse these into a single dimension of reality testing. However, a number of treatment approaches, such as cognitive behavioral therapy, focus on the treatment of hallucinations and delusions in somewhat different ways, and thus we feel it is important for clinicians to have a means by which to separately assess the severity of such symptoms separately and to be able to track change in each domain of symptom individually(Addington and Mancuso 2009; Gleeson et al. 2009; Velligan 2009).

Restricted Emotional Expression and Avolition 

In addition, we felt it important to distinguish between two different domains of negative symptoms: 1) restricted emotional expression; and 2) avolition. Exploratory and confirmatory factor analyses of symptom assessment scales such as the Schedule for the Assessments of Negative Symptoms (SANS) at the item level have overwhelmingly supported separate negative symptom factors for Flat Affect/Diminished Expression and Avolition/Asociality/Anhedonia.^{39, 90-97} Factor analytic studies of the SDS have also supported two separate factors of Diminished Emotional Expression and Avolition.^{99, 100} Additional support for a two-factor model of negative symptoms comes from replication of the finding across heterogeneous samples. Separate factors for Flat Affect/Diminished Expression and Avolition/Asociality/Anhedonia have been identified in heterogeneous groups of patients with any psychotic disorder^{93, 95, 97} as well as schizophrenia spectrum patients^{34, 39, 90-92, 94, 96} and deficit syndrome patients.^{99, 100} Furthermore, these factors were found in patients on^{34, 94, 96, 99} and off medication³⁹ and in first-episode⁹² and chronic⁹¹ patients. Separate factors for affective flattening and avolition appear to hold up cross-culturally. Factor analyses of data collected from patients in the United States,^{34, 39, 91, 94, 96, 99} Canada,⁹² Spain,⁹⁵ South Africa,⁹⁰ Australia,⁹³ and Japan,¹⁰⁰ all supported Flat Affect/Diminished Expression and Avolition/Asociality/Anhedonia as separate factors, providing further evidence for recognizing deficits in affect and volition as two distinct symptom domains in schizophrenia.

A primary reason for asking clinicians to rate each of these types of negative symptoms separately is evidence that they may differentially predict factors such as clinical presentation(Strauss et al. in submission), functional outcome(Strauss et al. in submission; Tattan and Creed 2001), cognitive deficits (Gur et al. 2006; Malaspina and Coleman 2003; Suslow et al. 1998), emotional deficits(Gur et al. 2006; Henry et al. 2007), and neurobiological impairments(Dichter et al. 2009; Dowd and Barch in press; Fahim et al. 2005; Gur et al. 2007; Waltz et al. 2009).

Cognitive Function

In addition to including dimensional assessments of the criterial symptoms of psychosis, we feel it is also important to include dimensional assessments of other important clinical phenomena that are relevant to treatment planning and prognosis.  First, we propose to include a dimensional assessment of cognitive impairment.  There is ample evidence that a large percentage of individuals with schizophrenia and other psychotic disorders suffer from impairments in a range of cognitive domains (e.g., Reichenberg et al. 2008), and growing evidence that the level of cognitive impairment predicts functional abilities (social, occupational, living status) (e.g., Cervellione et al. 2007; Green et al. 2004; Heinrichs et al. 2008b; McClure et al. 2007).

Despite the importance of cognition to understanding function in schizophrenia and other psychotic disorders, we do not propose to include cognitive deficits as a Criterion A symptom of schizophrenia or any other psychotic disorder.  This is because cognition may not be useful as differential diagnosis tool.  The profile of cognitive impairments in similar across the non-affective and affective psychosis (Depp et al. 2007; Hill et al. 2004; Reichenberg et al. 2008; Schretlen et al. 2007; Smith et al. 2009), though the level of impairment may be greater in non-affective psychoses (Depp et al. 2007; Hill et al. 2004; Krabbendam et al. 2005; Schretlen et al. 2007). Perhaps one of the clearest examples of such a result was recently provided by Reichenberg and colleagues (Reichenberg et al. 2008). These researchers compared individuals with consensus research diagnoses of schizophrenia, schizoaffective disorder, major depressive disorder with affective features and bipolar disorder with psychotic features.  The individuals with schizophrenia and schizoaffective disorder were overall more impaired than the individuals with psychotic mood disorders, and the prevalence of cognitive impairment was higher in schizophrenia and schizoaffective disorder by definitions that they examined.  However, the individuals within all four groups showed the same relative pattern of impairment across cognitive domains, with the greatest impairment in verbal memory, and the least impairment in visual processing general verbal ability. Depp et al provided another compelling example in their studying comparing individuals with schizophrenia, bipolar disorder and healthy controls (Depp et al. 2007).  Unlike, Reichenberg et al., Depp found that the bipolar patients were as impaired as the schizophrenia patients on many of the tests.  Further, the profile of impairment was very similar across groups, with the most impairment in information processing speed for both groups, and the least impairment in crystallized IQ.  In addition, there is evidence that the factor structure of cognition is very similar across schizophrenia and bipolar disorder (Czobor et al. 2007). There are of course some exceptions to these results, and some studies that have shown differences across psychotic disorders in the pattern or severity of cognitive impairment (Heinrichs et al. 2008a). However, the wealth of data suggest that this separation is not sufficient to justify inclusion of cognition as a Criterion A symptom of schizophrenia.

Nonetheless, it remains clear that cognitive function is important for understanding functional status in schizophrenia (Bowie et al. 2008; Green et al. 2000; Green et al. 2004), as well as other psychotic disorders, including bipolar disorder (Gruber et al. 2008; Jaeger et al. 2007; Martinez-Aran et al. 2004; Tabares-Seisdedos et al. 2008), and  that cognitive deficits are not well treated by current antipsychotic medications (e.g., Keefe et al. 2007).  Thus, we have included a dimensional assessment of cognition because it is important to highlight the potential need for additional treatments specifically targeting cognitive remediation in schizophrenia and other psychotic disorders (e.g., Marder 2006; Marder and Fenton 2004).  We will be recommending that it is optimal to obtain a formal neuropsychological assessment in individuals with psychosis to fully understand the nature and severity of their cognitive impairments.  However, should this not be possible, we will be recommending that at minimum, clinicians conduct a brief and easy to validity administer assessment of cognition such as one of the many variations of the Digit Symbol Substitution Test.  These measures are very brief (under 5 minutes), are highly reliable, and are strong predictors of the severity of cognitive impairments shown by individuals with schizophrenia on large batteries of cognitive tests (Dickinson 2008; Dickinson et al. 2008; Dickinson et al. 2007). The growing research on other methods for assessing cognitive function (e.g., self-report, clinician interview) suggests that these methods do not provide valid assessments of objective cognition impairment or functional outcome in psychosis(Green et al. 2008) and thus these are not sufficient as a basis for assessing cognitive impairment in schizophrenia.

Depression and Mania

We also propose to include dimensional assessments of depression and mania for all psychotic disorders.  There is growing evidence that schizoaffective disorder does not represent a distinct nosological category separate form schizophrenia (e.g., Malhi et al. 2008; Owen et al. 2007; Peralta and Cuesta 2009). However, at the same time there is good evidence that the severity of the mood pathology present in individuals with schizophrenia indicates important information about prognosis and outcome (Bowie et al. 2006; Crumlish et al. 2005), and the need for treatments specifically targeting these mood symptoms (e.g., Addington et al. 1998; Peralta and Cuesta 2009).  Thus, dimensional assessments of depression and mania for all psychotic disorders will serve to alert clinicians to look for the presence of mood pathology and treat it were appropriate.  

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