Acalculia is a neurological disorder that affects a person’s ability to perform basic mathematical calculations. It is often associated with brain lesions or damage to the parietal lobe, which is responsible for mathematical processing. This disorder can significantly impact an individual’s daily life, making simple tasks such as counting or telling time challenging. In recent years, there has been a growing interest in understanding the underlying causes and challenges of acalculia, leading to a better understanding of its diagnosis and treatment. This article will explore the various aspects of acalculia and shed light on the difficulties faced by individuals with this condition in numerical processing.
Acalculia (not to be confused with dyscalculia) is an acquired impairment in which patients have difficulty performing simple mathematical tasks, such as adding, subtracting, multiplying and even simply stating which of two numbers is larger. Acalculia is distinguished from dyscalculia in that acalculia is acquired late in life due to neurological injury such as stroke, while dyscalculia is a specific developmental disorder first observed during the acquisition of mathematical knowledge. The name comes from the Greek “a” meaning “not” and Latin “calculare”, which means “to count”. Variations Acalculia is associated with lesions of the parietal lobe (especially the angular gyrus) and the frontal lobe and can be an early sign of dementia. Acalculia is sometimes observed as a “pure” deficit, but is commonly observed as one of a constellation of symptoms, including agraphia, finger agnosia and left-right confusion, after damage to the left angular gyrus, known as Gerstmann’s syndrome (Gerstmann, 1940; Mayer et al., 1999). Studies of patients with lesions to the parietal lobe have demonstrated that lesions to the angular gyrus tend to lead to greater impairments in memorized mathematical facts, such as multiplication tables, with relatively unimpaired subtraction abilities. Conversely, patients with lesions in the region of the intraparietal sulcus tend to have greater deficits in subtraction, with preserved multiplication abilities (Dehaene and Cohen, 1997). These double dissociations lend support to the idea that different regions of the parietal cortex are involved in different aspects of numerical processing.