What post-birth factors can have an impact?

ADHD is largely influenced by genetics, but post-birth environmental factors can influence its risk and severity.

These factors can affect how it presents and develops, meaning it may worsen symptoms or trigger an earlier onset.

Can diet have an effect?

Food may not directly cause ADHD, but it can worsen the symptoms.

A diet high in refined sugar, ultra-processed foods, and saturated fats increases the risk of attention deficit, hyperactivity, and other ADHD symptoms. In contrast, vegetables, legumes and nuts were associated with a reduction of ADHD symptoms.^{1 2}

Your diet affects your brain health through the gut-brain axis – the connection between your digestive system and brain. Neurotransmitters like dopamine and serotonin are partially made in the gut and are directly influenced by food.

A poor diet negatively affects dopamine and serotonin levels, which can affect overall brain health. This can lead to energy crashes, difficulty focusing, memory issues and mood changes.

But it is important to note that a bad diet may also be a consequence of ADHD. People with ADHD have low dopamine levels, so they may eat certain foods, like those high in sugar, to compensate for this and temporarily feel a dopamine boost.

It can be hard to improve your diet with ADHD, but there are some things you can do to make it easier, such as:

• Keeping a food diary to track how you feel after eating a certain food
• Therapy
• Finding healthier alternatives
• Taking medication

Can having a bad childhood lead to ADHD?

A bad childhood can't directly cause ADHD, but it may worsen the symptoms. The evidence for this is limited as it’s difficult to test, especially when ADHD can be caused by multiple factors.

Improper parenting can lead to increased injury risk, including traumatic brain injuries, which is common in children with ADHD. As a result, these children may have worsened ADHD symptoms as they get older.³

Additionally, the parenting style may affect how well a child manages their ADHD symptoms. Without proper parental support, the child may lack the skills to manage inattention, find it hard to focus and regulate their emotions.

Although studies argue that maltreatment and childhood neglect don’t directly cause ADHD, a bad childhood can lead to worsening symptoms and comorbid conditions later in life, including trauma and anxiety.⁴

Can environmental toxins cause ADHD?

Exposure to substances like lead and pesticides, especially in early childhood, may affect brain development and worsen ADHD.

Lead

Lead is a metal element that's naturally occurring, but exposure to it has increased over the years because of human use. Early exposure to lead can cause neurotoxicity, which can lead to worsening ADHD symptoms.⁵

BPA

BPA is a chemical that's associated with ADHD.

It's found in many plastic products, including cosmetics, toys and general household use. Early exposure to BPA has been found to significantly increase hyperactivity, which can exacerbate ADHD symptoms.⁶

Pesticides 

Certain pesticides, like pyrethroid pesticides, may also have harmful effects.

Mice exposed to pyrethroid are shown to have side effects that resemble ADHD, such as hyperactivity, memory issues and attention deficits. Similarly, one study found that children with detectable levels of pyrethroid were two times more likely to be diagnosed with ADHD.⁷

These three are just a handful of the many substances that may increase the risk of ADHD or exacerbate symptoms.

ADHD: Is it nature or nurture?

ADHD is likely the result of a combination of factors, rather than a single cause. Genetics play a major role, but that doesn’t mean we ignore the environmental influences.

ADHD is a condition that isn’t yet fully understood. As research continues, it may uncover the complex interactions between genetic and environmental factors that contribute to ADHD.

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Overview

Pre-birth factors

References:

1. Del-Ponte, B., et al. (2019). Dietary patterns and attention deficit/hyperactivity disorder (ADHD): A systematic review and meta-analysis. Journal of Affective Disorders, 252, 160-173.

2. Lange, K. W., et al. (2023). Nutrition in the Management of ADHD: A Review of Recent Research. Current Nutrition Reports, 12(3), 383.

3. Ayaz AB, et al. Factors related with unintentional injuries in children with newly diagnosed attention-deficit/ hyperactivity disorder. Int J Inj Contr Saf Promot. 2016;23(1):93-8.

4. Stern, A., et al. (2018). Associations between abuse/neglect and ADHD from childhood to young adulthood: A prospective nationally-representative twin study. Child Abuse & Neglect, 81, 274.

5. Moore, S., et al. (2022). The Association between ADHD and Environmental Chemicals—A Scoping Review. International Journal of Environmental Research and Public Health, 19(5), 2849.

6. Rochester, J. R., et al. (2018). Prenatal exposure to bisphenol A and hyperactivity in children: A systematic review and meta-analysis. Environment International, 114, 343-356.

7. Richardson, J. R., et al. (2015). Developmental pesticide exposure reproduces features of attention deficit hyperactivity disorder. The FASEB Journal, 29(5), 1960.