The current tools used to define and diagnose mental disorders, including the Diagnostic and Statistical Manual of Mental Disorders and the International Classification of Diseases, have added specificity to the psychiatric nomenclature. However, their stereotypic rigidity in classification has resulted in the failure to identify the full range of potentially debilitating psychiatric symptoms with which patients may present. A spectrum model of psychopathology is more adept at recognizing the subclinical or threshold symptomatology that may occur concomitantly with core psychiatric disorders. The authors discuss the development of a spectrum approach to the diagnosis of mental disorders, which offers the potential to improve treatment selection and therapeutic outcomes.

This paper describes a model of psychopathology termed the panic-agoraphobic spectrum. The model has been constructed by identifying different psychopathologic and clinical domains that incorporate and extend the diagnosis of panic disorder as described in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV).

Categorical classifications do not take into account the subthreshold, atypical, and often enduring symptoms that accompany the core manifestations of full-blown mental disorders. These often-neglected spectrums of symptoms, however, may be as distressing and debilitating as the full-blown disorders and can have unrecognized importance in selection of and response to treatment. At the Department of Psychiatry, Neurobiology, Pharmacology, and Biotechnology, Institute of Psychiatry of the University of Pisa, Italy, a spectrum approach to mental disorders (eg, bipolar, obsessive-compulsive, eating, and panic disorders) has been used extensively and has proven effective in clinical practice.

The need for systematic identification and assessment of a broad array of symptoms and behavioral features has led, as a first step, to the conceptualization of the panic-agoraphobic spectrum model. In collaboration with researchers from the University of Pittsburgh, PA, and elsewhere, the University of Pisa scientists have further refined the panic-agoraphobic spectrum model and have developed a structured interview for this spectrum called the Structured Clinical Interview for Panic-Agoraphobic Spectrum. The rationale, clinical usefulness, and heuristic significance of the panic-agoraphobic spectrum model are discussed below.

Available data from the literature supporting the hypothesis that partial manifestations of the panic-agoraphobic spectrum may be as clinically relevant as a full-fledged syndrome were reviewed. These partial expressions of disorder may occur singly or in connection with other mental disorders. In particular, we have examined evidences indicating relationships of panic-agoraphobic spectrum with other mental disorders in childhood and adolescence and with psychotic disorders. Their importance in childhood and adolescence is significant because we believe that these symptoms influence adult behavior and are viewed, at a later time, as atypical symptoms. Panic-agoraphobic spectrum syndromes, both in their full-fledged and partial manifestations frequently co-occur with other mental disorders and are likely to be associated with significant impairment either when occurring singly, partially, or comorbidly. Several conditions typical of childhood, such as separation anxiety, school phobia, and other symptoms related to the concept of “behavioral inhibition” seem to be connected with the panic-agoraphobic spectrum and deserve attention in relation to the development of different anxiety and mood disorders in subsequent phases of the life cycle. Identification of panic-agoraphobic spectrum features is also important within the realm of psychoses where they may substantially affect phenomenology, course of illness, and treatment response.

Panic disorder occurs frequently with different forms of cardiovascular disease and hypertension. The 13 panic symptoms described in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) often overlap with manifestations of cardiovascular disorders, raising problems in the differential diagnosis. In order to explore in greater detail the phenomenology of panic symptoms in cardiovascular patients, the Structured Clinical Interview for Panic-Agoraphobic Spectrum (SCI-PAS) was administered to 111 patients with hypertension and 29 patients with a recent myocardial infarction.

With regard to the frequency of endorsement of many of the symptoms assessed on the SCI-PAS, more than 40% of the cardiovascular patients who failed to meet the DSM-IV criteria for panic disorder did not significantly differ from the 10% of cardiovascular patients who did fulfill the criteria for panic disorder. A third distinct subgroup comprising 48.6% of the cardiovascular patients reported a significantly smaller number of SCI-PAS symptoms than the other two groups.

These preliminary findings suggest the existence of a relatively large proportion of cardiovascular patients who present with physical and psychological symptoms that are potentially related to panic disorder and that may provoke considerable subjective distress. Further studies are needed to clarify the nature of these symptoms and their potential interference with treatment and symptomatology of cardiovascular disease.

Separation anxiety has long been of interest in psychiatry. The term refers to both a phenomenon of normal psychological development and to the symptoms of a common childhood psychiatric disorder, classified in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), and the International Statistical Classification of Diseases and Related Health Problems, Tenth Edition (ICD 10), as separation anxiety disorder. Available epidemiological studies suggest a prevalence rate of this disorder of about 4%. Treatment studies using cognitive behavioral therapy and/or medication are reported in the literature. There is also evidence that symptoms of separation anxiety may occur in adulthood, though this is far less widely known. We consider childhood and adult separation anxiety to be a component of panic spectrum, described in other papers of this issue.

A small and somewhat confusing literature addresses the question of outcome of childhood separation anxiety disorder, with support for a weak association between childhood separation anxiety and adult panic disorder. We believe there is a suggestion of a stronger association of the childhood condition with persistence of a similar syndrome of adult separation anxiety. Symptoms of adult separation anxiety may be a manifestation of panic spectrum, as we suggest. Such symptoms may represent a separate, specific clinical entity, or symptomatic separation anxiety may occur as a manifestation of a range of Axis I disorders, and may respond to treatment of these disorders. In any case, we urge researchers and clinicians to begin to attend to the possibility that adult psychiatric patients may suffer from clinically significant symptoms of adult separation anxiety.