Is It Unusual for a Dementia Patient to Do Basic Math in Their Head?

Dementia is a condition that affects the brain and can lead to various changes in a person’s thinking, memory, and behavior. One question that often comes up is whether it’s unusual for someone with dementia to still be able to do basic math in their head. In this blog post, I will talk about this topic in detail, considering the extent of cognitive function loss in dementia patients and whether they can still handle tasks like doing taxes.

Is it unusual for a dementia patient to do basic math in their head?


When we talk about basic math, we mean tasks like addition, subtraction, multiplication, and division—things we use in our daily lives without much thought. For someone with dementia, who may struggle with memory and thinking skills, it might seem surprising if they can still manage these calculations in their head. However, the ability to do basic math can vary greatly among individuals with dementia.

Extent of Cognitive Function Loss

Dementia is not a one-size-fits-all condition. It can affect people differently and progress at different rates. In the early stages, a person may still be able to perform tasks that require basic math skills. They might be able to add up a grocery bill or calculate how much change they should receive. However, as the condition progresses, these abilities may decline.

One reason for this variability is that dementia primarily affects certain areas of the brain responsible for memory, language, and reasoning. While these areas may deteriorate over time, other parts of the brain, including those involved in basic math skills, may remain relatively intact—at least in the early stages of the disease.

Can they also do taxes?

Doing taxes involves more than just basic math. It requires organization, attention to detail, and the ability to understand complex forms and instructions. For someone with dementia, these tasks can become increasingly challenging as the condition progresses.

In the early stages of dementia, a person may still be able to manage their finances and complete simple tax returns. However, as the disease advances, they may struggle with more complex calculations and paperwork. They may also have difficulty remembering important deadlines or understanding changes to tax laws.

What does the research say?

In this study conducted by Marinella Cappelletti, Brian Butterworth, and Michael Kopelman from the Institute of Cognitive Neuroscience at University College London, the researchers aimed to understand how patients with acquired brain disorders perform in tasks related to numbers and calculations.

They tested 76 participants, dividing them into two groups: 40 healthy individuals and 36 patients with various neurological conditions such as Alzheimer’s dementia, frontotemporal dementia, semantic dementia, progressive aphasia, and focal brain lesions like those seen in herpes simplex encephalitis (HSE).

Each participant underwent a series of tests, both on paper and computerized, to assess their numerical abilities and calculation skills. Additionally, patients with degenerative conditions and HSE were also tested on tasks unrelated to numbers to gauge their semantic knowledge.

The results of the study revealed several important findings. Firstly, despite the involvement of the parietal brain area, which is crucial for numerical processing, all patients, including those with parietal lesions, demonstrated intact understanding of number quantity.

Secondly, patients who had impaired semantic knowledge actually showed better-preserved numerical knowledge. This suggests that numerical abilities might be somewhat independent of general semantic knowledge.

Thirdly, most patients, regardless of their specific condition, displayed impaired calculation skills. However, there were exceptions among patients with semantic dementia and HSE, as they tended to perform better in calculations compared to other patients.

Based on these findings, the researchers concluded that numeracy skills can vary considerably among patients with different neurological conditions. They also suggested that numerical abilities might be linked to brain regions beyond just the parietal areas traditionally associated with number processing.

Overall, this study sheds light on the complex relationship between brain disorders and numerical abilities, highlighting the need for further research in this area.


In conclusion, the ability of a dementia patient to do basic math in their head can vary depending on the individual and the stage of the disease. While some may retain this skill in the early stages, it’s not uncommon for it to decline as the condition progresses. 

When it comes to tasks like doing taxes, the challenges can become even greater, requiring more than just basic math skills. It’s important for caregivers and loved ones to provide support and assistance as needed, helping to manage finances and navigate the complexities of everyday life for someone living with dementia.

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