Arithmetic Weakness (Acalculia)

By | June 8, 2022

Acalculia or arithmetic weakness is the loss or impairment of previously acquired arithmetic skills, which in the majority of cases is due to damage to cortical centers, especially in the left hemisphere. Accordingly, acalculia must be distinguished from dyscalculia, which is usually identified as a specific developmental disorder in childhood or school age.

What is dyscalculia?

Acalculia (arithmetic weakness) is an acquired impairment in dealing with arithmetic quantities (arithmetic operations, number handling) that is caused by damage to the cortical centers of the brain, usually the left hemisphere (brain half). For what is urinary stones, please visit

While other intelligence is not restricted, acalculia can manifest itself in everyday life, among other things, through difficulties in dealing with money, telephone numbers and/or times, in estimating distances, price discounts or quantities as well as through impairments in the processing of arithmetic symbols. Depending on the severity of the underlying lesion, heterogeneous forms of dyscalculia can appear.

While some are only affected by complex arithmetic operations, others affected by acalculia may be restricted in elementary arithmetic, such as adding or subtracting single-digit numbers.


Primary acalculia, which occurs rather rarely, can be caused by damage to the speech-dominant cortex as a result of an insult (stroke). The impairment known as secondary acalculia, on the other hand, is observed more frequently and can be associated with a reduction in brain performance due to memory disorders, attention disorders and a pronounced tendency to perseveration (pathological persistence or dwelling on a thought or a spoken utterance).

Acalculia is also associated with damage to the parietal and temporal lobes in agraphia and finger-foot-toe agnosia. In addition, acalculia occurs as a symptom of Gerstmann’s syndrome (also Angularis syndrome), which also manifests itself through agraphia, finger agnosia, right-left disorder and in which the left angular gyrus is usually affected.

Since arithmetic operations are partially controlled by language functions, acalculia in many cases correlates with aphasia, which can occur as a speech disorder caused by the central nervous system, for example as a result of strokes, tumors, cerebral hemorrhage, inflammation or intoxication.

Symptoms, Ailments & Signs

The main symptom of acalculia is the presence of an acquired impairment in dealing with numbers and other arithmetic quantities. How this weakness in arithmetic manifests itself depends primarily on the extent of the neurological disorder present. The impairments in some of those affected only become apparent during complex arithmetic operations.

In other cases, acalculia shows itself through difficulties with numbers, distances, telephone numbers, times and dates. Due to their poor arithmetic skills, those affected are often unable to handle money because they cannot correctly assess price discounts and quantities. Problems with counting occur, especially when aphasia is present at the same time.

In addition, the auditory understanding of numbers is often limited. Those affected repeatedly make mistakes in reading and writing and in the regular arrangement of numbers. They also have difficulties with arithmetic, since the ability to carry out operations on numbers is severely impaired in acalculia.

Arithmetic symbols are often confused or not understood. In serious cases, the ability to calculate is not available at all or is often limited to individual types of basic calculations. The other intelligence of those affected is not further restricted by the disease.

Diagnosis & History

There are various screening methods for detecting acalculia, in which the potentially impaired arithmetic operations can be checked in specific tests.

Possible screening methods are the so-called number processing and calculation test (ZRT) in combination with a test for cognitive estimation and the NPC test (Number Processing and Calculation Battery). In general, the most important representations of numbers and Transcoding methods (for example, the Arabic number “26” can be assigned to the sound sequence “twenty-six”), the arithmetic basic arithmetic operations as well as counting, approximate calculations (estimated and rough estimate calculations) and the numerical memory span were tested.

Acalculia should be differentiated from dyscalculia, dementia and numerical illiteracy in the differential diagnosis. In order to be able to rule out a premorbid underperformance, the level of performance prior to the lesion should also be taken into account. In general, the prognosis and course of acalculia depends on the type and location of the underlying lesion. Although the spontaneous course of acalculia has not been conclusively examined, an improvement can usually be assumed five to six months after the triggering event (including a stroke).


Acquired dyscalculia is not necessarily associated with complications. Most of the time, however, the memory impairment has a serious underlying cause, such as a stroke or a tumor, which can cause further problems. After the incident that triggered it, many sufferers experience persistent attention deficit disorders or have difficulty concentrating.

Neurological deficits are often added and the quality of life of those affected decreases overall. The dyscalculia itself can cause complications if the patient had a lot to do with numbers at work before the incident. Jobs in accounting, for example, can usually no longer be carried out with arithmetic weaknesses. Even after the acalculia has receded, those affected must be retrained from scratch.

This represents a great psychological burden, which cannot be overcome without outside help, especially if there are serious accompanying symptoms. There are usually no complications during therapy. Occasionally, however, sedatives and stimulants are prescribed and these are always associated with side effects. The medications prescribed to treat the causative condition can also cause symptoms and occasionally cause interactions and allergic reactions.

When should you go to the doctor?

Arithmetic weakness is noticed nowadays in the development and growth process of the child. Parents and teachers are responsible for organizing help and medical support in the event of irregularities. In some cases, acalculia occurs in an adult human. This is preceded by a triggering event such as a stroke or damage to the brain. Because of the underlying condition, the patient is already receiving medical treatment and should address changes in their numeracy skills.

Help is needed as soon as the understanding of numbers is disturbed. The severity of the irregularity differs between the patients. There may be abnormalities in simple or complex arithmetic tasks. A doctor should be consulted for clarification as soon as, in addition to a limitation in school performance, there are also special features in everyday life. If you have poor money management or an inability to judge distances and quantities, a doctor’s visit is recommended.

If times cannot be read, understood or implemented meaningfully in practice, this is worrying. If you have problems with entering the date, assigning house numbers or using the telephone, you should see a doctor. Repeated errors in reading and writing numbers are another sign of an irregularity. If there is a lack of an auditory understanding of numbers, a doctor is also needed.

Treatment & Therapy

In the case of acalculia, the therapeutic measures are aimed either at restoring (restoring) the impaired functions and abilities or at reorganization. In the case of acalculia, the therapeutic measures are aimed either at restoring (restoring) the impaired functions and abilities or at reorganization in which other intact ones remain cognitive functions are used to compensate.

In the context of restitution, the lost knowledge is primarily trained through intensive practice units in which the damaged functions, in particular transcoding and retrieving the arithmetic knowledge already stored, are trained in order to establish a stable link between the specific calculation problem at hand and the correct solution.

Here, the consideration of everyday-specific exercises (including reading the time, handling money and calculating change) as well as job-related tasks when reintegrating into working life is recommended as a rehabilitation goal. In addition, you should start at the level of difficulty at which the specifically affected person shows impairments.

Through therapeutic approaches aimed at reorganizing arithmetic skills, specific strategies and basic arithmetic rules (e.g. 5 x 6 = (5 x 10) – (5 x 4)) are conveyed to compensate for the functions affected by acalculia within the framework of exercise units aimed for.


Acalculia can only be prevented to a limited extent. For example, as part of arteriosclerosis prophylaxis, the risk of a stroke and thus possible acalculia can be reduced.


In the case of arithmetic weaknesses or acalculia, aftercare aims to strengthen the newly acquired feel for numbers and mathematical processes. This prevents these skills from being forgotten and the arithmetic weakness from reoccurring. The sooner the learning disability is diagnosed, the better the chances of recovery.

The psychological aspect of arithmetic weaknesses is no less important: Children with acalculia often suffer from school anxiety or psychosomatic symptoms such as nausea before school starts or anxiety during math lessons. Self-confidence can be affected if no success is achieved despite repeated arithmetic exercises.

If classmates experience the child’s learning difficulties in class, the risk of bullying is also very high. If one or more of these situations apply, a psychologist must be consulted to prevent permanent damage to the child’s self-esteem. In the therapy sessions, ways are worked out together with the child to strengthen self-confidence.

You can do that yourself

In order to gradually restore the ability to calculate as best as possible in the case of acalculia, intensive training is necessary. The degree of difficulty must be determined individually by a doctor and increases gradually. Exercises that are tailored to the everyday life of the person concerned are best suited. This includes reading the time and calculating with money. More difficult connections can be introduced later.

If you have a pronounced weakness in arithmetic, it is a good start to first integrate simple arithmetic rules into everyday life. Special learning material for arithmetic weaknesses can be used for this purpose. Another option is textbooks. Group training with other sufferers is also recommended. If this is not possible, relatives who are not sick can also help the sick person. You can support the patient individually. For example, mental arithmetic or writing down longer numbers can be practiced.

Depending on the severity of the arithmetic weakness, support in everyday situations is also necessary. Since acalculia is often the result of a disorder in the left hemisphere of the brain, it makes sense to train it specifically. Not only arithmetic tasks, but also language exercises and other brain teasers can be used for this.

Arithmetic Weakness (Acalculia)