There are currently no standardized Occupational Therapy (OT) assessments identified in the literature that exclusively assesses or screens for agnosia. However, various assessments are used in the process of diagnosing an individual with agnosia. In particular, these assessments are heavily used during neuropsychological testing as tools to rule out alternative explanations for an individual's recognition deficits. Some of these are identified in the table in the previous webpage on Neuropsychological Testing. For example, to determine for the possibility of dementia, the Dementia Rating Scale can be used. A reason why there are limited standardized assessments is possibly because of the rare nature of agnosia. Agnosia accounts for less than one percent of all neurological patients (Zihl & Kennard, 1996), which means that there is a small number of cases that can be studied.
Despite no OT assessments existing that directly assesses for agnosia, there are several standardized screening assessment batteries that measures and screens visual perceptual skills. Examples include the The Rivermead Perceptual Assessment Battery (RPAB) and the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA). The following table highlights several common assessments batteries for assessing visual perception in adults.
From the above tables, it is important to point out that only the Ontario Society of Occupational Therapy Perceptual Evaluation (OSOT) exclusively addresses agnosia. It lists visual agnosia as one of its six functional areas. There are two test items for the functional test area of visual agnosia: Shape Recognition and Match 9 Shapes to Form Board. Despite only the OSOT having agnosia listed as a functional area or subtest, there is no need to conclude that other assessments cannot be used to assess for visual agnosia. For example, the RPAB involves subtests that measures deficits at different levels of perceptual processing. This includes simple processing such as copying shapes and matching colours. These tasks can be used to assess for apperceptive and colour agnosias, respectively.
The Occupational Therapy Adult Perceptual Screening Test (OT-APST) is another standardized screening tool that includes exclusive testing for visual agnosia in one of its subtests. The OT-APST is a brief screening tool that enables Occupational Therapists to test for the presence of visual perception impairment. The following are general information about this assessment (Zeltzer, n.d.):
- Used with clients with stroke
- Consists of 25 items across 7 subtests: agnosia, visual relations, unilateral neglect, body scheme, apraxia, acalculia, and functional skills
- Only available in English
- Takes 20-25 minutes to administer
The subtest for agnosia has 5 items and is organized as follows (Zeltzer, n.d.):
- Colour agnosia: The client is requested to name/identify six colors in an array to evaluate color recognition skills.
- Object agnosia: The client is presented with a stapler that he/she must name and describe in terms of its use to demonstrate object recognition and naming.
- Figure-ground: The client must recognize five items in an overlapping array to demonstrate figure-ground/perceptual closure skills.
- Shape constancy: The client is presented with a mixed array of 10 shapes of varying sizes and positioned at different angles. The client must name/point on command to four common shapes to demonstrate shape recognition ability.
- Reading-alexia: The client is asked to read a passage of text that has indentations of random lengths on both sides of the page to be sensitive to attention/neglect changes to both the left and right side of space.
The OT-ASPT was published in 1993 by Deidre Cooke and later revised in 2001. Since then, there has been minor research regarding its reliability and validity. The research indicate adequate to excellent reliability but varied results regarding its validity. Please click on the following link to learn more about this assessment's measurement properties and where to obtain it: http://strokengine.ca/assess/module_otapst_quick-en.html
Various databases were searched, including PubMed and Google Scholar, to search for any (OT and non-OT) tests exclusive for the assessment for agnosia. The only assessment found is called the Visual Perception Test for Agnosia (Japanese Society of Aphasiology, 1997), which was developed in Japan in 1977 for assessing higher order visual perceptual abilities. It was difficult to find reliable information (norms, time to administer, reliability, etc.) on this assessment partly because it is written in Japanese.
This assessment has been used multiple times in the literature for research regarding visual agnosias (Wada & Yamamoto, 2001; Moriyama, Muramatsu, Kato, Mimura, Akiyama & Kashima, 2007) and other visual perceptual conditions (Otsuka et al., 2005; Mimura, Watanabe, Kato, & Kashima, 2005). More research needs to be done to allow this assessment to be validated and translated into English.