90 Schizophrenia Spectrum and Other Psychotic Disorders
disorder is not a distinct nosological catego ry. Thus, dimensional assessments of depres-
sion and mania for all psychotic disorders alert clinicians to mood pathology and the need
to treat where appropriate. The Section III sc ale also includes a dimensional assessment of
cognitive impairment. Many individuals with psychotic disorders have impairments in a
range of cognitive domains that predict functi onal status. Clinical neuropsychological as-
sessment can help guide diagnosis and treatm ent, but brief assessments without formal
neuropsychological assessment can provide us eful information that can be sufficient for
diagnostic purposes. Formal neuropsychological  testing, when conducted, should be ad-
ministered and scored by personnel trained in  the use of testing instruments. If a formal
neuropsychological assessment is not conducted, the clinician should use the best avail-
able information to make a judgment. Furthe r research on these assessments is necessary
in order to determine their c linical utility; thus, the assessments available in Section III
should serve as a prototype to  stimulate such research.
Schizotypal (Personality) Disorder
Criteria and text for schizotypal personality disorder can be found in the chapter “Person-
ality Disorders.” Because this disorder is cons idered part of the schizophrenia spectrum of
disorders, and is labeled in this section of ICD-9 and ICD-10 as schizotypal disorder, it is
listed in this chapter and disc ussed in detail in the DSM-5 chapter “Personality Disorders.”
Delusional Disorder
Diagnostic Criteria 297.1 (F22)
A. The presence of one (or more) delusions with a duration of 1 month or longer.
B. Criterion A for schizophrenia has never been met.