Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, hyperactivity and impulsivity that begins in childhood and can persist into adulthood (1). ADHD is estimated to affect around 5% of children and 2.5% of adults worldwide (2).

One area that can be impacted by ADHD is mental math skills. Mental math refers to the ability to calculate answers mentally without relying on pen and paper or calculators. It involves holding numbers in your working memory while manipulating them to get the answer (3).

Mental math skills are important for everyday life and for building foundations in math and science. Difficulties with mental math can make tasks like figuring out if you have the right change after a purchase more challenging. It can also make higher-level math classes more difficult.

## Does ADHD affect mental math skills?

Research suggests that ADHD does negatively impact mental math skills in children, adolescents and adults. Some key research findings include:

– A meta-analysis of 22 studies found that children with ADHD performed significantly worse on mental math fluency tests compared to peers without ADHD (4).

– A study of 277 college students found that students with ADHD had significantly lower mental math scores than non-ADHD peers (5).

– Multiple studies have found that adults with ADHD perform worse on mental arithmetic tests than controls (6,7).

– Brain imaging studies show that youth with ADHD exhibit altered activation in brain regions linked to working memory and attention during mental math tasks compared to controls (8,9).

So the evidence clearly indicates that ADHD is associated with poorer mental math skills across the lifespan. Exactly how and why ADHD impacts mental math is still being investigated.

## Why does ADHD affect mental math skills?

Researchers believe there are several reasons why ADHD could negatively affect mental math performance:

### Working memory deficits

– Working memory involves temporarily holding information in mind and manipulating it. It’s vital for mental math (10).

– ADHD is linked to impairments in visuospatial working memory – the working memory used for mental math (11).

### Inattention

– Inattention makes it harder to keep focused when doing multi-step mental math (12).

– People with ADHD are more prone to careless math errors due to lapses in attention (13).

### Altered brain function

– ADHD involves structural and functional differences in some brain regions important for working memory and math (14).

– These brain differences may contribute to mental math difficulties.

### Math anxiety

– Children and adults with ADHD often have higher math anxiety (15,16).

– Anxiety can take up valuable working memory resources and hinder mental math performance (17).

### Processing speed

– Mental math requires quickly retrieving math facts from long-term memory.

– ADHD is linked to slower processing speed which can impair rapid math fact retrieval (18).

So in summary, deficits in working memory, attention, math anxiety, processing speed and altered brain function in ADHD may all contribute to poorer mental math skills.

## Are some types of mental math more affected than others?

Research indicates certain types of mental math operations are more difficult for people with ADHD.

### Mental math fluency

Mental math fluency refers to quickly and accurately answering simple math problems like:

– 9 + 5 = ?

– 17 – 9 = ?

Studies consistently show that both children and adults with ADHD perform worse on tests of mental math fluency (4,5).

Difficulties rapidly retrieving math facts from long-term memory likely underlie fluency deficits. Slower processing speed in ADHD could also contribute.

### Multi-step mental math

Multi-step mental math requires holding steps in working memory like:

– 37 + 12 + 59 = ?

Steps:

1. 37 + 12 = 49

2. 49 + 59 = 108

Performing multi-step mental math is linked to substantially greater prefrontal cortex activation compared to simple mental math in brain imaging studies (19).

Since ADHD involves structural and functional differences in the prefrontal cortex, this likely explains why multi-step mental math is disproportionately impaired (14).

### Mental manipulation

Mental manipulation requires transforming numbers in working memory such as:

– Reverse the order of the digits in 37

– Take the number 53 and add 5

Studies find mental manipulation tasks that heavily tax working memory are more difficult for youth and adults with ADHD (7, 20).

### Estimation

Estimation involves getting a rough approximation of a math problem like:

– 23 x 4 is approximately equal to ?

Some research shows that children with ADHD struggle more with numerical estimation tasks (21).

Estimation requires maintaining focus over time which may be impeded by inattention in ADHD.

So in summary, mental math fluency, multi-step problems, mental manipulation and estimation appear most impacted in people with ADHD. Difficulties with working memory and attention likely underpin these weaknesses.

## Do mental math deficiencies persist over time?

Multiple longitudinal studies have examined whether children with ADHD are able to catch up in mental math as they get older. Results show that deficits in mental math skills and math achievement test scores tend to persist over time:

Study | Participants | Findings |
---|---|---|

Daley and Birchwood (2010) | 62 children with ADHD, followed for 2 years from ages 7-9 | Children with ADHD showed no improvement in mental math skills over time compared to peers. |

Zentall et al. (1994) | 44 children with ADHD, followed for 4 years from grades 2-5. | Children with ADHD continued to score lower on math achievement tests than peers over time. |

Frick et al. (1991) | 29 children with ADHD, followed for 4 years from grades 2-5 | Math achievement test scores remained significantly lower in the ADHD group at follow up. |

Researchers suggest that early difficulties with mental math likely compound over time, as higher-level math classes require strong basic skills.

However, some recent studies suggest that intensive math interventions can help improve mental math and math skills in students with ADHD (22, 23).

So while deficits are persistent, targeted interventions may have potential to improve mental math abilities to some degree.

## How are mental math difficulties assessed?

Mental math skills can be assessed using short, standardized tests that are untimed or have generous time limits to accommodate ADHD.

Some examples of mental math tests used in ADHD research include:

– The Arithmetic subtest of the Wechsler Individual Achievement Test (WIAT) (5)

– Math Fluency subtest of the Woodcock-Johnson Tests of Achievement (WJ-IV) (4)

– The Mental Arithmetic Test (MAT) (7)

These tests require the person to mentally solve math problems presented aloud or visually without paper/pencil. More complex mental manipulation tasks may also be included.

Performance is then compared to age/grade norms. Significantly slower speed or more inaccurate responses than peers indicates difficulties.

In clinical settings, similar mental math fluency probes can quickly screen for potential issues that require further evaluation.

Getting a full picture also involves assessing verbal math problem solving skills, math anxiety, processing speed, working memory and math achievement.

## How are mental math difficulties managed and treated?

For students with ADHD who struggle with mental math, experts recommend the following approaches:

### Targeted interventions

– Interventions that focus on improving number sense, math facts fluency, working memory and decreasing math anxiety can help strengthen mental math skills in ADHD (22,24).

– Cognitive behavioral therapy helps lower math anxiety (25).

– Working memory training may improve attention and mental math in ADHD (26).

### Universal design for learning

Principles include (27):

– Allowing calculators and equation sheets to limit working memory demands.

– Providing additional time for math assignments and tests.

– Using visual representations like number lines.

### Individualized education programs (IEPs)

– IEPs can provide accommodations like reduced math homework, untimed tests, and separate settings.

### Medication

– Stimulants like methylphenidate can improve attention, working memory and mental math fluency in ADHD (28).

For adults with ADHD, similar strategies plus workplace accommodations and coaching can support mental math skills. Assistive technology like calculation apps and voice assistants can also compensate for difficulties.

## Conclusion

In summary, research clearly demonstrates that ADHD negatively impacts mental math abilities across the lifespan. Deficits are seen in math fluency, multi-step problems, mental manipulation and estimation likely due to working memory impairments and inattention. Without intervention, gaps in performance persist over time. Screening for math difficulties is important for identifying individuals who need strengthened skills. Targeted interventions, accommodations, technology tools and medication can help support those with ADHD who struggle with mental math. Addressing math difficulties is key for improving academic and career outcomes for individuals with ADHD.