Diagnosis and Classification of the Schizophrenia Spectrum Disorders

1 The Schizophrenia Construct After 100 Years of Challenges 7psychotic incidents can be looked upon as part of a dimensional continuum that aremagnified as a result of various genetic and environmental factors rather than asrigid diagnostic criteria for disorders [68]. Thus, we have at least three axes of thecontinuum: (a) within affected persons (SZ, SAD, MDD, BPD), (b) from affectedpersons to non-affected persons in the general population, and (c) among relativesof probands with FP.Psychotic symptoms such as hallucinations and delusions, disorganized speechand behavior, and negative symptoms are distributed along a continuum that extendsfrom SZ to psychotic mood disorders [69–71]. Regarding the number of putativesymptom dimensions, there is some consensus that there are 3–6 symptom dimensionsunderlying the latent structure of FP (Table 1.1). Repeat examinations ofpatients revealed results that further support the validity, internal consistency andinter-rater reliability of the PANSS factor models of SZ psychopathology [72–78].In addition, poor insight [79, 80], elevated emotional distress [81, 82], cognitive[83–85] and quality of life impairments [86], disruption of everyday functioning[87–90] should be added to phenotypic characteristics of functional psychoses.Table 1.1 Syndrome dimensions underlying functional psychosisSyndrome dimensionsReferencesType I consisted of positive symptoms such as delusions andCrow [227, 228]hallucinations.The type II syndrome is more or less chronic and is characterized bynegative symptoms, such as flattening of affect, poverty of speechand loss of drive; these symptoms are related to poor outcome, poorresponse to neuroleptic drugs, and structural pathology in thecentral nervous system.Positive and negative symptomsAndreasen andOlsen [229]Positive, negative, and general psychopathological scales Kay et al. [230]Positive, negative, excited and depressed, cognitive dysfunction, Kay, Sevy [231]suspiciousness and stereotypic thinkingAnergia, thought, activation, paranoid, and depression factors Kay [232]Psychomotor poverty, disorganization, and reality distortionLiddle [72]; Peralta,Cuesta [73];Keefe et al. [74]Negative, psychoticism, disorganization Arndt et al. [233,234]; Andreasenet al. [235]Negative, positive, excited, cognitive, anxious/ depressiveNegative, positive, activation, dysphoric mood and autisticpreoccupation factorsNegative, positive, cognitive, excitement and depression componentsLindström, VonKnorring [236];Lindenmayeret al. [237]White et al. [75]Lindenmayer et al.[237]; Lançonet al. [76]