• Recent research suggests a possible link between attention deficit hyperactivity disorder (ADHD) and irritable bowel syndrome (IBS).

  • The disruption of gut microbiota could be a key element bridging ADHD and IBS.

  • Additional research is needed as some experts dispute the connection between these two conditions.

A recent meta-analysis has uncovered what researchers describe as a “significant positive correlation” between the risk of developing irritable bowel syndrome (IBS) and having attention deficit hyperactivity disorder (ADHD).

Scientists point to disruptions in gut microbiota as a potential underlying cause that connects ADHD with gastrointestinal issues.

This new insight was published in the respected journal Scientific Reports.

This analysis could have everyday implications for individuals living with ADHD.

“IBS significantly impacts the life quality of those afflicted. When occurring alongside ADHD, it complicates the management of ADHD symptoms,” the researchers noted.

They further explained, “Our findings indicate that the gut microbiome could be the missing link in understanding the co-occurrence of ADHD and IBS, suggesting that medical professionals should monitor gastrointestinal symptoms in individuals diagnosed with ADHD.”

However, the researchers acknowledged several limitations in their study, including a geographic concentration of data from Asia and a limited age range of participants in the examined studies.

An external expert has voiced significant criticisms of the research methodology.

Emeran Mayer, MD, a professor at the University of California Los Angeles and director of the UCLA Gail and Gerald Oppenheimer Family Center for Neurobiology of Stress, criticized the heterogeneity of the included studies regarding age, location, size, and possibly diagnostic criteria for IBS and ADHD. “There is no consistent evidence from previous robust studies to support a link between IBS and ADHD,” Mayer explained to Healthline.

Are IBS and ADHD linked?

To form their conclusions, the researchers analyzed 11 previous studies involving approximately 3.8 million participants, which included about 175,000 individuals diagnosed with ADHD.

All of these studies were conducted in the last 25 years.

According to their findings, individuals with ADHD are 1.63 times more likely to develop IBS compared to those without ADHD.

The study found no significant links between ADHD and other types of intestinal disorders.

Research indicates that an altered gut microbiome is implicated in several neuropsychiatric disorders such as Parkinson’s disease, multiple sclerosis, and Alzheimer’s disease.

Furthermore, children with ADHD are reported to experience more gastrointestinal problems like constipation and gas compared to their peers without the disorder.

These observations suggest a connection between the gut-brain axis and ADHD, according to the researchers.

However, Mayer remains skeptical, stating, “The research only establishes a correlation rather than a causal relationship between ADHD and IBS, or the gut microbiome and ADHD prevalence.”

He added, “Given the high comorbidity of ADHD with other psychiatric disorders, including anxiety, and the high comorbidity of IBS with anxiety and depression, a correlation between IBS and ADHD is feasible. IBS involves altered gut-brain interactions often accompanied by increased anxiety levels. A consistent alteration in the gut microbiome in IBS patients has not been conclusively demonstrated.”

Max Wiznitzer, MD, a pediatric neurologist not involved in the study, suggests other explanations for the link between ADHD and IBS, mainly attributing it to comorbid anxiety and/or depression.”

“The study by Ng et al in Scientific Reports may have overlooked other potential reasons by focusing too heavily on gut microbiota,” Wiznitzer commented to Healthline.

What to know about ADHD

Attention-deficit hyperactivity disorder is recognized as a mental health disorder characterized by impulsive behavior.

Common symptoms of ADHD include:

  • trouble concentrating on tasks

  • being easily distracted

  • difficulty remaining seated for prolonged periods

  • tendency to interrupt others during conversations

The American Psychiatric Association categorizes ADHD into three types:

  • primarily inattentive

  • primarily hyperactive-impulsive

  • a combination of both

While the exact cause of ADHD is still under investigation, genetic factors are believed to play a significant role.

The researchers involved in the current study highlight that ADHD is associated with various negative outcomes for individuals.

Such outcomes include an increased risk of engaging in smoking, substance use disorders, risky sexual behaviors, higher driving risks, and suicidal tendencies. They also note that ADHD imposes a substantial economic burden on affected families and society at large.

Additionally, ADHD often coexists with other neuropsychiatric conditions like autism spectrum disorder and bipolar disorder.

ADHD is typically diagnosed in childhood but can persist into adulthood. It is more common in males than females.

Recommended treatments for ADHD include behavioral therapy and medications. Lifestyle adjustments such as a balanced diet, regular physical activity, sufficient sleep, and limited screen time are also advised.

Mayer mentioned that several therapies could be beneficial for ADHD patients.

“Various behavioral techniques have proven effective for ADHD patients. Similar cognitive behavioral techniques have also shown benefits for IBS patients,” he stated.

What to know about IBS

Irritable bowel syndrome encompasses a variety of intestinal symptoms, including abdominal pain, bloating, gas, diarrhea, and constipation.

IBS is more prevalent in women and typically affects younger adults more frequently than older individuals.

While symptoms may be mild for some, they can be severe enough to interfere significantly with daily activities for others.

The specific causes of IBS remain unclear, though factors such as an overly sensitive colon and immune system issues are believed to contribute.

Certain stressors and anxiety can trigger IBS symptoms. Additionally, specific foods are known to provoke IBS, including:

  • beans

  • onions

  • some fruits

  • some dairy products

  • certain carbs

There are several strategies to help alleviate IBS symptoms, such as:

  • engaging in regular exercise

  • reducing caffeine intake

  • managing stress levels

  • using probiotics

  • quitting smoking

Nutritionists often recommend that individuals with IBS follow a low FODMAP diet, which involves avoiding certain carbohydrates.

“I advocate for a comprehensive treatment approach that includes tailored dietary advice, various behavioral techniques, mindfulness-based stress reduction, and cognitive behavioral therapy,” Mayer explained.

“In cases where IBS is particularly stubborn, low-dose tricyclic antidepressants can be effective. For those with severe psychiatric issues like anxiety or depression—which is less than 10% of all patients—I prescribe SSRIs,” he added.

Wiznitzer offered a straightforward suggestion for those suffering from IBS. “Address the underlying anxiety and depression, and you’ll likely see an improvement in IBS symptoms,” he concluded.