Symptoms of other mental disorders, such as oppositional defiant disorder, anxiety, autism spectrum disorder, and bipolar disorder, can overlap with those of ADHD. This can complicate the diagnosis process and make it more challenging to find an effective treatment plan.

Having complex ADHD can disrupt a person’s daily functioning and performance. In addition to ADHD’s hallmark symptoms, further difficulties may be triggered from the condition itself.

For example, a student with ADHD may experience anxiety when their performance at school suffers. But when the ADHD is properly treated, these symptoms can reduce or disappear altogether.

However, those with complex ADHD have full-fledged secondary disorders that require their own treatment. Such comorbid conditions are common.

Research shows that up to 80% of adults with ADHD have at least one co-existing condition. And anywhere from 60% to 100% of children with ADHD are affected by another issue, according to a review published in World Journal of Clinical Cases.

The most common co-existing conditions noted in the review, followed by the percentage of children thought to be affected, are:

• Learning disorders (70%)
• Autism spectrum disorder (59%)
• Tic disorders (55%)
• Oppositional defiant disorder (30-50%)
• Depressive disorder (12-50%)
• Bipolar disorder (5-47%)
• Anxiety disorders (15-35%)
• Conduct disorder (3.5-10%)

Related: Oppositional Defiant Disorder: Symptoms and Management

There is also a significant overlap between ADHD and substance use disorders (SUD). According to research published in 2021 in Alcohol and Alcoholism, half of adults from ages 20-39 with ADHD have had a SUD in their lifetime. This is more than twice the number of non-ADHD young adults (23.6%) who have had a SUD.

In other words, as some researchers have suggested, complex ADHD—the presence of one or more additional conditions alongside ADHD—may be the rule rather than the exception.

COMPLEX ADHD SYMPTOMS

Let’s look at some symptoms for each of the above disorders that commonly co-occur with ADHD.

1. Learning disorders. A 2015 study noted that it’s fairly common for children with ADHD to exhibit the symptoms of specific learning disorders.

Researchers defined these as “significant difficulties in learning one or more academic domains, such as reading, writing, listening, speaking, reasoning, and performing mathematical calculations and problem solving.”

2. Autism spectrum disorder (ASD). According to Children and Adults with Attention-Deficit/Hyperactivity Disorder (CHADD), ADHD is the most common coexisting condition in children with ASD.

In both conditions, affected functions may include movement, language, memory, social skills, decision making, impulse control, time management, focus, and organization skills.

3. Tic disorders. Children and adults with tic disorders display involuntary vocal and/or physical tics, such as eye blinking, yelling, or humming. These movements and vocalizations occur suddenly and can be difficult to control.

Tic disorders are typically grouped into three categories: Tourette’s syndrome, persistent/chronic motor or vocal tic disorder, and provisional tic disorder.

4. Oppositional defiant disorder (ODD). Children with ODD may have frequent and/or prolonged temper tantrums or engage in excessive arguments with adults. They may be exceptionally defiant, angry, disruptive, or cruel. Similarly, adults with ODD may be angry or irritable, engage in aggressive or hostile behavior, or show contempt for authority figures.
5. Depressive disorder. Also called clinical depression or major depressive disorder, this mental health issue affects millions of Americans. As a mood disorder, it’s characterized by persistent low moods, including feelings of sadness, emptiness, or hopelessness.

Individuals may lose interest in activities they previously enjoyed, feel fatigued or lethargic, or engage in suicidal thoughts or behavior.

Related: How Untreated ADHD Can Cause or Worsen Depression

6. Bipolar disorder. Bipolar spectrum disorder (BSD), formerly called manic depression, is a brain disorder marked by cycles of mania and depression. BSD is associated with severe changes in mood, energy and activity levels, which compromise the ability to carry out everyday tasks.

Depressive episodes involve the symptoms noted above, under #5. Manic episodes manifest as an influx of energy, less need for sleep, fast speech, grandiose ideas, and/or racing thoughts. Both of these states occur at more intense levels than a person’s normal ups and downs.

7. Anxiety disorders. While feelings of anxiety are common among Americans, anxiety disorders are more severe, interfering with daily life.

Symptoms include extreme worry and nervousness, even leading to panic attacks. Physical symptoms, such as a racing heart, trembling hands, dizziness, and muscle tension, can also accompany anxiety disorders.

8. Conduct disorder (CD). CD goes beyond typical childhood or teenage rebelliousness. In children and teens, it often includes aggressive behavior, such as hitting or biting others, bullying, animal cruelty, or vandalism. Generally, people with conduct disorders have difficulty following rules and show a lack of regard or empathy for others.
9. Substance use disorder (SUD). Addictions can involve illegal substances, prescription medications, and/or alcohol. Through repeated and heavy usage, drug users change the way the brain experiences pleasure. Over time, usage of the drug increases and leads to life-damaging effects.

People with addictions typically lack self-control around the substances they’re using. So, even though they experience negative consequences and they want to stop using, they continue to use.

DIAGNOSING COMPLEX ADHD

Getting the right complex ADHD diagnosis is a critical step in the treatment process. According to one study on the condition, a wide range of assessments are required to diagnose both ADHD and co-existing disorders.

A helpful tool in complex ADHD diagnosis and treatment is brain SPECT imaging. Single photon emission computed tomography evaluates blood flow and activity in the brain. Based on over 250,000 SPECT brain scans on tens of thousands of patients, Amen Clinics has identified seven types of ADHD, each associated with its own brain pattern.

Related: Treating the Brain for 7 Types of ADHD

SPECT can also help pinpoint signs of other co-occurring disorders. For example:

• Substance use disorders are associated with a toxic or scalloped appearance of the brain.
• Overactivity in the deep limbic system—the brain’s emotional center—is associated with depression.
• Heightened activity in the basal ganglia is often seen in people with anxiety disorders.

These brain scans can also help identify or rule out other potential causes for brain and mood changes, such as head trauma, infection, or toxin exposure.

COMPLEX ADHD TREATMENT

Because more than one issue is at play in complex ADHD, treatment needs to be personalized and comprehensive. Treatment for complex ADHD may include:

• Medication
• Parent training
• Psychotherapy, such as cognitive behavioral therapy (CBT)
• Innovative therapies, such as neurofeedback
• Diet modifications
• Lifestyle changes
• Nutritional supplements

Additional treatments for complex ADHD will depend on the co-occurring disorder that is diagnosed.

GETTING HELP FOR COMPLEX ADHD

Because ADHD so often co-exists with other mental health conditions, it’s important to remain on the lookout for additional issues, even after receiving an ADHD diagnosis and treatment plan. When treating ADHD has not helped reduce or eliminate other mental health symptoms, it might be time to seek evaluation for a comorbid condition.