Acalculia, the inability to understand numbers

Imagine for a moment that you cannot understand numbers and calculations as simple as 2 or 2+2. This alteration of mathematical abilities, known as acalculia, It was described by the neurologist Salomon Henschen in 1925. and to this day it astonishes the world of science.

What if we told you that an area of ​​your brain is responsible for mathematical calculations? It would be something like an integrated calculator, right? In this sense, acalculia is a deficit that directly affects the ability to calculate due to acquired brain damage.

The different types of acalculia

Acalculias are divided into two large groups according to the altered capacities and the damaged areas. Generally, the affected hemisphere is the left one, in charge of logical reasoning. Likewise, the classification of acalculias will depend on both the area of ​​the left hemisphere affected and the degree to which the skills are altered.

Primary acalculia

Primary acalculia is a defect in calculation skills not linked to other disorders. Patients lose the ability to understand numerical concepts and therefore combine them.

The main failures are seen in the execution of operations and in more abstract issues, such as the use and interpretation of signs. The lesions are associated with the frontal lobe of the left hemisphere. This lobe is considered the conductor of the orchestra in our brain, so its alteration leads to an inability to alternate mathematical concepts. So we can differentiate two clear symptoms of primary acalculia:

Anarimetics. Inability to perform arithmetic calculations.Asyntactic. Loss of computational sense.

Secondary acalculia

Secondary acalculia consists of the alteration of mathematical skills in association with other neuropsychological disorders. Then secondary acalculia can derive from a linguistic, spatial and executive function deficit in general. In summary, we can group them into the following categories:

Aphasic acalculia. Defects in the calculation come from linguistic alterations. The inability to understand and encode numerical language results in an inability to operate with it.Alexic acalculia. Mainly linked to problems with reading and recognizing numerical symbols. The patient cannot understand through reading.Agraphic acalculia. Agraphia is the inability to communicate and express oneself through writing. This disorder does not come from the inability to execute the movement, but from the lack of understanding of the act of writing on a symbolic level. Consequently, the patient is unable to write numbers.Frontal acalculia. Perhaps the most common among acalculias. It is closely linked to attention disorders. These patients tend to persevere, which consists of repeating errors systematically. This condition is caused by the inability to identify errors and propose new solution strategies.Semantic acalculia. It is a difficulty in managing relationship concepts. A clear example would be the inability to associate mathematical problems with the operations necessary for their solution.Spatial acalculia. It would be a consequence of an injury to the right hemisphere. Difficulty performing arithmetic calculations is associated with problems in spatial processing.

How is primary acalculia diagnosed?

The most important thing is to observe that the symptoms are expressed both orally and in writing. Primary acalculia consists of a loss of numerical concept, which can sometimes be confused with different aphasic symptoms. It is necessary to verify that the deficit is due to the loss of the concept and not to a failure in the verbal understanding of the instructions..

Why do patients with frontal lesions fail in numerical tasks?

First of all, solving numerical tasks requires a plan in which different mathematical concepts are integrated. To solve a sum, for example, it is necessary to understand the concept of additivity. Second, most mathematical problems require abstract reasoning. The lack of inhibition in syndromes typical of a frontal injury makes this process difficult by failing concentration..

Finally, both the selective attention and the sequential integration required by numerical operations are affected by the poor integration of visual and/or auditory stimuli. As we mentioned before, the frontal lobe is the conductor of the brain orchestra; If it has errors, it will be more difficult to arrange the information in a way that favors the resolution of the problem.

Acalculia and other conditions

Acalculia can be seen in aphasic subjects as long as their linguistic abilities are affected.. In Broca’s aphasia, for example, the deficit manifests itself in the syntax applied to calculation. In alexical acalculia, for its part, the deficit is correlated with reading difficulties.

A more explanatory example is the pure alexiawhere the difficulties in verbal and literal interpretation of written language They are evidenced in the erroneous interpretation of numbers, magnitudes and hierarchies.

Other ways to detect acalculia

In agraphia, acalculia may appear related to the inability to write quantities. Thus, the type of acalculia will depend on the type of agraphia.

In Wernicke’s aphasia, for example, the patient presents errors in copying numbers from dictation. To compensate for this deficit in verbal comprehension, these patients usually invent numbers and assign them their own order.

Addressing acalculia

The main thing is to understand that it is a very different disorder from dyscalculia, which consists of a development and learning problem, and therefore requires other intervention strategies. For its part, The diagnosis of acalculias is usually in the hands of neuropsychologists, who use various tests. In them, the person has to perform mental and written arithmetic operations, successive operations, interpretation of arithmetic signs and alignment of numbers in columns.

The treatment of primary acalculia will depend on the type of lesion and its severity. Since lost nerve tissue cannot be recovered, Rehabilitation usually focuses on one objective: teaching new strategies based on neuroplasticity.

Although recovery will never be complete, tools must be given to improve the person’s adaptation. On the other hand, the treatment of secondary acalculias will vary depending on the associated disorder. The advancement of technology provides computer tools and applications that are a hope for patients.

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