IBS (Irritable bowel syndrome) and ADHD (Attention deficit hyperactivity disorder) seem to be two completely different conditions, one is related to gut health and the other to psychological behaviour. However, recent research has shown a promising connection between these two conditions and how these two can affect the quality of life of a person, immensely suggesting people with ADHD are more prone to developing IBS and vice versa.

This article will focus on how both conditions are interconnected and may influence or trigger each other's occurrences. Before we delve into the relationship between IBS and ADHD, let's first understand the two disorders briefly.

What are IBS and ADHD?

Definition of IBS

Irritable bowel syndrome is a chronic condition characterized by episodic abdominal pain and changes in bowel movements like diarrhoea, constipation, or both. It is a functional disorder, which means that there are no visible signs of damage or disease in the gastrointestinal (GI) tract. Symptoms of IBS include repeated episodes of abdominal pain in the form of cramping, distension, bloating, or burning, associated with diarrhoea, constipation, eating specific foods, or stress. Other symptoms may include:¹

• Mucus in stool
• Urgency
• The feeling of incomplete evacuation
• Anxiety or depression
• Sleep disturbance
• Fibromyalgia
• Chronic pelvic pain

Depending on the type of associated bowel movements, there are 4 categories of IBS with equal prevalence, as given below;

• Mostly diarrhoea and abdominal discomfort
• Mostly Constipation and abdominal discomfort
• Alternative loose stools and Constipation with abdominal discomfort
• Undefined subtype, symptoms vary

Definition of ADHD

Attention deficit hyperactivity disorder is one of the most common neurodevelopmental disorders of childhood that often lasts into adulthood. Children and adults with ADHD may have trouble focusing and paying attention and might show impulsive behaviour and overactivity. There are three subtypes of ADHD Depending on the type of symptoms strongly showing in the individual:²

• Predominantly inattentive type: the individual has trouble focusing, getting organized, finishing tasks, and following instructions or actively listening and communicating during a conversation. The person is easily distracted and forgets details of their daily routine
• Predominantly hyperactive-impulsive presentation: the person fidgets and talks a lot. It is hard for them to sit still for a duration of time that is normal for other individuals compared to the same age group. These individuals are used to interrupting people while they talk, impulsively finishing their sentences, speaking at inappropriate times, and putting themselves in risky situations, so they often find themselves in accidents and and injuries
• Combined presentation: symptoms related to both the above types mentioned are present in these individuals and the occurrence of the symptoms may vary at different times or occasions

General symptoms of ADHD are as follows:

• Daydreams a lot
• Forget or lose things a lot
• Squirm or fidget
• Have a hard time resisting temptation
• Have trouble taking turns
• Have difficulty getting along with others

The link between IBS and ADHD

A study showed that young adults aged 17 to 35 years old with ADHD had more diagnoses of functional GI disorders like dyspepsia, abdominal distention, chronic constipation, and IBS.³ Similar patterns of coexisting IBS and ADHD are also seen in children aged 3 to 16 years old.⁴ Moreover, if a patient is diagnosed with IBS, their child is more likely to have ADHD compared to other kids whose parents don't have IBS.⁵

Some key factors contributing to the link between IBS and ADHD are as follows.

The gut-brain axis

The gut microbiome forms a complex system that continuously communicates with the central nervous system. Various microbiota metabolites are essential in forming vital neural pathways, and brain function. Changes in gut microbiota are observed in both ADHD and IBS. For instance, a slight increase in the Bifidobacterium genus has been noted in patients with ADHD, contributing to an abnormally diminished reward anticipation pathway (due to reduced dopamine levels), which impact brain function and behaviour.

An imbalance of the microbiota may cause abnormal neurotransmitter release, potentially causing anxiety or decreased motor control. These changes might result in lasting or permanent modifications to the central nervous system (CNS) and its function.⁴

Furthermore, the gut microbiota plays a critical role in the immunoregulation of the human body. An imbalance in the gut flora could lead to the release of inflammatory markers in the systemic circulation, resulting in the gradual destruction of the blood-brain barrier and possible neuroinflammation seen in ADHD. Recent research has also shown that IBS are related to hypersensitivity of the nerves in the gastrointestinal tract wall, disturbing the gut-brain axis.⁴

Stress and emotional dysregulation

Individuals with ADHD often have to deal with stress and anxiety. Similarly, stress is one of the most important triggering factors for IBS, as an increased level of stress leads to gut hypersensitivity, exacerbating IBS symptoms.⁶

Individuals with IBS experiencing abdominal pain, bloating, diarrhoea, and constipation can also become more distracted because of the symptoms, thus aggravating ADHD. Additionally, IBS can disrupt sleep patterns, leading to fatigue and frustration, further impairing attention.

Diet and nutrition

Individuals with ADHD can also suffer from eating disorders due to their impulsive behavior. They might develop unhealthy eating habits, irregular meal patterns, and poor dietary choices. This may result in decreased nutritional intake and abnormal BMI, aggravating IBS symptoms.

Conversely, individuals with IBS sometimes have to follow certain dietary restrictions, such as adopting a low FODMAP diet, that can cause nutritional deficiencies, and alter the gut microbiota, potentially affecting brain function.⁷ 

ADHD medication 

Most ADHD medications have GI side effects like nausea, vomiting, or changes in bowel movements inconsistent medication adherence in people with ADHD can lead to inconsistent exposure to these side effects, that can again potentially trigger IBS.

Diagnosing IBS and ADHD

Diagnosis of IBS is made solely based on the patient’s clinical history using ROME 4 criteria, as no laboratory or imaging tests are currently available for this purpose. Similarly, The diagnosis of ADHD is guided by DSM 5 criteria and a detailed history and evaluation of individual social, academic, and emotional function.

Management strategies

As recent studies and data support that both IBS and ADHD are strongly interlinked, it raises the need for a comprehensive treatment approach that enables one to deal with both conditions. A holistic treatment approach is not possible without healthy lifestyle modifications, so it’s highly recommended for individuals suffering from IBS and ADHD to adopt good eating habits and exercise regularly.

Following are a few recommendations that can be incorporated into daily lives to help people manage both conditions together.

Healthy and balanced diet

Maintaining a healthy, balanced diet rich in fibre, lean protein, whole grains, fruits, and vegetables is crucial, as our food choices directly influence gut bacteria. Focus on mindful eating can help identify potential food triggers. Individuals experiencing symptoms exacerbation related may benefit from consulting a dietitian to explore tailored dietary adjustments. 

Additionally, supplements like probiotics, zinc, and magnesium can be included in the diet following the advice of a health professional, as it increase the amount of good bacteria in the gut.⁷ 

Hydration is equally important, as it aids digestion and alleviates fatigue, complementing the benefits of a nutritious diet.

Stress management

Managing stress levels can be challenging but is important for individuals with ADHD and IBS. Techniques like Yoga, meditation, deep breathing exercises, and regular physical activity can help with stress management. The choice of techniques may vary based on individual preferences and what they find most effective. Engaging in hobbies like gardening, playing sports, spending time in nature, or reading can also be valuable for stress relief.

Sleep hygiene

Having regular, good-quality sleep for 6-8 hours is important for reducing stress and maintaining biological rhythm that affects hormonal and cognitive function.

Summary

The exact cause of both ADHD and IBS is unknown; however, both disorders share common risk factors like environment and lifestyle. Understanding these factors with scientific evidence can unravel the complex relationship between the two, and empower individuals to manage both conditions more effectively, improving their productivity and self-esteem.