- Excerpt from Chapter 19, Anxiety Disorders , Sherva Cooray,
M.D., FRCPsych, DPM, MBBS, Susan Gabriel, PMHNP, APRN, BC, and
Valerie, Gaus, Ph.D.
The application of Anxiety Disorder diagnostic criteria in the DSM-IV-TR
requires that the patient have adequate cognitive function and
communication skills. The extent to which the criteria could be
validly and reliably applied in Persons with ID who have limitations
in both domains is thus problematic. This should be decided on the
basis of robust empirical data with relation to the phenomenology of
the disorders. While some phenomenological and objective features of
anxiety may be observed in this population, subjective elements such
as emotions may be harder, to elicit particularly with increasing
levels of disability.
To facilitate diagnostic reliability, supplementary guidelines,
incorporating behavioural equivalents within the context of
cognitive, developmental and adaptive functioning, are proposed.
Diagnostic Issues
The evidence-based knowledge on the assessment and diagnosis of
Anxiety disorders in Persons with Intellectual Disability is weak.
This may be because the current diagnostic classificatory systems,
ICD-10 and DSM- IV have been validated on populations with normal
intellectual functioning. As such, the diagnostic criteria in either
of the systems are not fully applicable to persons who have varying
degrees of difficulty in expressing the more complex cognitive
phenomena that occur in anxiety disorders (e.g. depersonalisation, derealisation).
Consequently, the subjective elements of the diagnostic criteria may
not be reported and might be inapplicable in this group. However, the
objective features of anxiety present in the general population such
as fear, trembling, flushing, irritability etc. are readily
observable in persons with intellectual disability. Avoidance of
specific situations reported by those with normal intellectual
functioning may not also be evident in persons with ID since
opportunities for choice may be limited.
All types of anxiety disorders have been described in people with
developmental disability particularly in those with mild ID. Anxiety
disorders are reported to be as common or more common in persons with
ID than in the general population according to some studies. However,
general surveys tend to identify substantially lower rates. Anxiety
may be under-diagnosed in this population. Diagnostic overshadowing
may result in under reporting of anxiety. It is also noteworthy that:
There may also be masking/modification of presenting symptoms of
anxiety as a consequence of sedative effects of psychotropic
medication. Further, when anxiety cannot be expressed, especially in
those with more severe disability, it may present as a behaviour disorder
The differential diagnosis of anxiety includes psychiatric disorders:
such as schizophrenia, mania, depression, adjustment reaction, and
physical/organic states presenting as anxiety such as alcohol and
drug withdrawal/intoxication, dementia, and multiple sclerosis for
example. Comorbidity is often an issue. Community studies in the
general population indicate that depression and anxiety commonly
occur together. At the primary care level it may be extremely
difficult to distinguish between the two, either because the person
complains of both emotions as having equal severity or because of few
associated symptoms that it is impossible to make a syndromic
diagnosis. Empirical evidence on co morbidity in persons with
intellectual disability is sparse.
The diagnostic criteria for Anxiety Disorders in the DSM-IV–TR
that rely extensively on subjective descriptions of symptoms are
difficult to apply in those with communication/cognitive problems.
Consequently in persons with ID, either the individual’s
subjective description of the symptoms or its observation by
others may need to be utilized to satisfy the diagnostic criteria.
All criteria for Anxiety Disorders in DSM-IV-TR are applicable
in borderline/mild/moderate ID. People who are non-verbal with
communication problems may nevertheless react with demonstrable signs
of fearfulness and distress in response to discrete situations described.
Observed instead of reported signs of increased arousal and behavior
change when encountered with the situation and/or avoidance of the
associated stimuli should be considered in people with severe
intellectual disability. Observable “signs” that constitute
Anxiety Disorders that may be applicable in lieu of the reported
subjective criteria in each category of the DSM-IV–TR and
behavioral correlates and or modifications that may enhance the
likelihood of diagnosis are outlined in the table of adapted
criteria. For example, symptoms such as palpitations, pounding heart,
or accelerated heart rate, sweating, trembling or shaking could be
reported and/or observed in all categories of people with ID. While
those with moderate/severe/ profound ID may not report sensations of
shortness of breath or smothering they may be observed. Other
criteria such as feeling of choking chest pain or discomfort, nausea
or abdominal distress feeling dizzy, unsteady, lightheaded, or faint,
derealisation (feelings of unreality) or depersonalisation (being
detached from oneself) fear of losing control or going crazy, fear of
dying, and paraesthesia (numbness or tingling sensations) are
applicable only in persons with mild or borderline intellectual
disability. Chills or hot flushes may be observed in persons with
severe/profound ID.
Adaptation of Diagnostic Criteria
While the recognition of Anxiety Disorders has been well documented
in persons with ID, the diagnostic reliability and validity could be
enhanced if the DSM-IV-TR could be modified within the context
of the developmental and cognitive level of functioning. It is
generally accepted that Anxiety Disorders criteria could be applied
reliably with minimal/moderate modifications in individuals with
Mild-Moderate ID. In those with severe to profound disability a new
set of criteria to reflect the nonverbal elements of the relevant
Anxiety Disorder would be more appropriate as tabulated below. The
number of criteria required for the purposes of diagnosis of panic
disorders in this sector of the population has been modified within
the context of the DSM proportionality. In the Severe/Profound
ID population, four of the thirteen possible symptoms for Panic
Attack cannot be detected. As such, the number of symptoms required
for diagnosis has been modified to a minimum of three out of nine,
thus maintaining the same ratio as in the DSM-IV-TR.
