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Acalculia Classifications

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Author: Brett McCardel, MS, CCC-SLP

What are the different types of acalculia? ๐Ÿง  ๐Ÿ”ขโฃ
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Several classification systems for acalculia have been proposed in the research literature, however the most widely accepted system comes from Ardila and Roselli (2002).โฃ
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In this classification scheme, acalculia types can be divided into two camps depending on the reason for arithmetic difficulties: Primary and Secondary Acalculias.โฃ
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Primary Acalculia
Anarithmetiaโฃ
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Secondary Acalculias
Aphasia Acalculiaโฃ
Alexia Acalculiaโฃ
Agraphic Acalculiaโฃ
Dysexecutive/Frontal Acalculiaโฃ
Spatial Acalculiaโฃ
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This classification system posits that acalculia can result from the loss of numerical concepts, executive functioning impairments, spatial disturbances, and/or language impairments. It is important to note that there is often overlap between these areas, and not everyone will fall neatly into a classification type.โฃ
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Primary Acalculia/Anarithmetia

  • Characterized by an impairment in understanding how the numerical system is organized

  • Symptoms include difficulties with:

    • Numerical concepts

    • Understanding number quantity and number positions relative to each other

    • Performing arithmetic sequences (e.g., count by 2)

    • Arithmetic symbol understanding

  • Can be present without language impairment, but is significantly correlated with aphasia (Basso et al., 2005)

Aphasic Acalculia

  • Characterized by calculation difficulties that arise from linguistic difficulties

  • Types of errors can include:

    • Semantic errors (100 read as "ten")

    • Syntax errors (difficulty understanding that hundred denotes different placements in "three hundred thousand, two hundred")

    • Morphological errors (15 read as "fifty")

    • Lexicalization errors (163 written as 100603)

    • Decomposition errors (632 read as "sixty three, two")

Alexic Acalculia

  • Characterized by calculation difficulties that arise from reading difficulties

    • Typically, mental calculation skills will be stronger

  • Digit-by-digit reading may be observed (359 is read as "three-five-nine")

  • Difficulty reading longer digit spans

Agraphic Acalculia

  • Characterized by calculation difficulties that arise from writing difficulties

    • Typically, mental calculation skills will be stronger

  • Difficulty will be seen in writing-to-dictation tasks and transcoding tasks

  • Types of errors can include:

    • Number omissions

    • Fragmentation (25 is written as "20-5")

    • Poorly formed writing due to motor impairment

Dysexecutive/Frontal Acalculia

  • Characterized by calculation difficulties that arise from executive functioning difficulties

  • Attentional impairments will result in difficulties maintaining focus on task

  • Perseveration of numbers may be observed

  • More fundamental arithmetic skills may be preserved, however complex mathematical concepts will be significantly impacted

Spatial Acalculia

  • Characterized by calculation difficulties that arise from spatial neglect

  • Mental calculation skills are superior to calculation involving reading or writing

  • Types of errors can include:

    • Exclusive overuse of one half of the page

    • Digit iterations (227 becomes 22277)

    • Feature iterations (e.g., extra loops are written for the number 3)

    • Difficulty maintaining horizontal direction when writing

    • Spatial disorganization

    • Writing over segments of the page already used

References and Further Readings

  • Ardila, A., & Rosselli, M. (2002). Acalculia and dyscalculia. Neuropsychology Review, 12(4), 179โ€“231. https://doi.org/10.1023/a:1021343508573

  • Ardila, A., & Rosselli, M. (2019). Cognitive rehabilitation of acquired calculation disturbances. Behavioural Neurology, 2019, 3151092. https://doi.org/10.1155/2019/3151092

  • Basso, A., Caporali, A., & Faglioni, P. (2005). Spontaneous recovery from acalculia. Journal of the International Neuropsychological Society : JINS, 11(1), 99โ€“107. https://doi.org/10.1017/S1355617705050113

  • Cohen, L., & Dehaene, S. (2013). Acalculia. In O. Godefroy (Ed.), The Behavioral and Cognitive Neurology of Stroke (pp. 101-113). Cambridge: Cambridge University Press. doi:10.1017/CBO9781139058988.011

  • Gonzalez, R., Rojas, M., Rosselli, M., & Ardila, A. (2021). Acalculia in aphasia. Archives of Clinical Neuropsychology: The Official Journal of the National Academy of Neuropsychologists, 36(4), 455โ€“464. https://doi.org/10.1093/arclin/acaa072