Understanding ADHD Comorbid Conditions

This page is educational information, not a diagnostic tool or medical advice. Many of these conditions share symptoms with ADHD, which is exactly why a professional evaluation matters. If any of this sounds familiar, bring it to your doctor or therapist.

One factor that largely contributes to the difficulty of diagnosing ADHD is that it frequently occurs with at least one comorbidity, such as depression, anxiety, or a learning disability. This is sometimes informally called "Complex ADHD," though that is not a clinical term. Identifying a co-occurring condition early makes it far easier to build a treatment plan that actually works.

Borderline Personality Disorder (BPD)

Borderline personality disorder is a mental health condition that affects the way you think and feel about yourself and others, causing problems functioning in everyday life. It can involve an unstable self-image, trouble controlling emotions and behavior, and a history of unstable relationships.

Like many other comorbidities, it shares a number of symptoms with ADHD and can be challenging to diagnose. People with BPD may find it difficult to tolerate being alone and can have a severe fear of abandonment or instability. Even when they want lasting, meaningful connections, intense anger, impulsivity, and frequent mood swings can drive people away. BPD usually becomes apparent by early adulthood, and symptoms often seem worst during young adulthood.

Some of the criteria used to diagnose BPD:

• Chronic feelings of emptiness
• Emotional instability in reaction to day-to-day events (for example, intense episodic sadness, irritability, or anxiety usually lasting a few hours and only rarely more than a few days)
• Frantic efforts to avoid real or imagined abandonment
• Identity disturbance, with a markedly or persistently unstable self-image or sense of self
• Impulsive and often dangerous behaviors, such as spending sprees, unsafe sex, substance abuse, reckless driving, and binge eating. Note: if these behaviors happen mostly during times of elevated mood or energy, they may be symptoms of a mood disorder rather than BPD.
• Inappropriate, intense anger or difficulty controlling anger (frequent displays of temper, constant anger, recurrent physical fights)
• A pattern of unstable and intense relationships that swing between idealization and devaluation (sometimes called "splitting")
• Recurrent suicidal behavior, gestures, or threats, or self-harming behavior
• Feelings of dissociation, such as feeling cut off from yourself, observing yourself from outside your body, or a sense of unreality

Opioid Use Disorder (OUD)

People with ADHD, particularly those who are not diagnosed until adulthood, face a lot of challenges they are unsure how to handle. That can contribute to other conditions like depression and anxiety, and some people end up self-medicating with opioids in the search for relief. This can lead to opioid use disorder (OUD) co-occurring with ADHD.

One study found that 16.5% of people with ADHD who are treated with stimulants also use opioids, compared with 13% of people who are not on stimulant therapy.

Like many other ADHD comorbidities, OUD has symptoms that overlap with ADHD, which makes diagnosis harder:

• Impulsiveness – people with OUD can act impulsively, either while high or in efforts to obtain more of the drug.
• Focus issues – someone with OUD is often preoccupied with obtaining or using drugs, which crowds out focus on anything else.
• Disorganization – drug use and loss of focus make it hard to stay on task and finish daily activities.
• Emotional dysregulation – drug use and withdrawal can cause frequent mood swings.

The opioid epidemic is a major issue, particularly in the US. Understanding some of the underlying reasons people turn to opioids – including undiagnosed, unmanaged ADHD – is part of working toward a solution. ADHD is hard to manage, and without a diagnosis people get desperate to fix themselves. Getting properly diagnosed and educated is the first step.

Autism Spectrum Disorder (ASD)

Autism Spectrum Disorder covers what used to be called Autistic Disorder, Asperger syndrome, and Pervasive Developmental Disorder – Not Otherwise Specified. All of them affect social and emotional skills and nonverbal communication. There are many parallels between ASD and ADHD, and some important differences.

More than half of people diagnosed with ASD also show evidence of ADHD – it is the most common co-occurring condition in autistic children. On the other side, up to a quarter of children with ADHD show low-level ASD traits, such as social-skill difficulties or strong sensitivity to clothing textures (see Sensory Processing Disorder).

Multiple studies have found a link between ADHD and ASD, but none has pinned down exactly why. Both conditions appear to have a genetic component; one study identified a rare gene that may be tied to both, which could help explain why they so often occur together. For years the American Psychiatric Association held that the two could not be diagnosed in the same person. That changed in 2013 with the DSM-5, which recognizes that they can co-occur.

What are the differences?

ADHD usually isn't diagnosed until a child is around 5 or 6, because before that the prefrontal cortex and executive-function skills haven't developed enough to evaluate reliably. Children with ADHD often struggle to stay on a single task, are easily sidetracked, find it hard to finish one thing before starting another, and are frequently unable to sit still. Some children with the predominantly inattentive presentation can hyperfocus on a topic that interests them, which makes it hard to switch attention to things like homework or chores.

Autism can often be identified earlier, between ages 2 and 3, based on how a child interacts with people and their environment. Autistic children are more likely to be intensely focused and unable to shift to the next task, and are frequently inflexible about routines – walking the same route, eating the same foods. Many autistic people are markedly over- or under-sensitive to light, noise, touch, pain, smell, or taste, and may have food preferences driven by color or texture, along with behaviors such as hand flapping. That same intense focus means autistic people are often able to retain detailed facts for long periods and may excel in math, science, art, and music.

For directories, assessments, and reading on the ADHD/autism overlap, see the ADHD + Autism Resources page.

Sensory Processing Disorder (SPD)

Research in children and adults with ADHD has found both under- and over-responsiveness to sensory input, along with difficulty moderating that input – most likely because of trouble filtering out irrelevant sensory information from the important stuff.

Both SPD and ADHD can leave a person feeling restless and unable to concentrate or relax. SPD commonly co-occurs with ADHD but can also occur on its own, and it can lead to a misdiagnosis of ADHD, especially in children who simply can't sit still or focus because they're overwhelmed.

Some symptoms of Sensory Processing Disorder:

• Picky eating, particularly avoiding foods with textures the person finds unpleasant
• Trouble settling down after activities
• Sensitivity to smells or sounds
• Dislike of certain fabrics, clothing items, or shoes
• Discomfort with certain movements, like swinging or riding an elevator

People with ADHD and SPD are much more prone to sensory overload. A few ways each sense can overload someone with ADHD:

• Touch – the texture of certain foods, fabrics, or body washes can be overwhelming. This is one of the most common sensory overloads for kids with ADHD, and girls may be particularly at risk. How clothes or shoes fit can be a constant frustration, and some people are bothered by bed sheets or car seats.
• Taste – some people with ADHD are sensitive to particular tastes, though food aversions are more often about texture.
• Sound – loud noises like a fire alarm, or subtle ones like someone chewing, can cause real stress. Loud restaurants and parties can be too much.
• Smell – smells can be overwhelming even when they're meant to be pleasant, like perfume or cooking food.
• Sight – visual clutter is overstimulating, which the disorganization that often comes with ADHD can make worse. Big crowded places like theme parks or casinos can be a lot.

Bipolar Disorder

Roughly 10 million people in the United States have bipolar disorder, and it often co-occurs with ADHD in adults. One study found that about 20% of people diagnosed with bipolar disorder are also diagnosed with ADHD. When the two occur together, the diagnoses are often missed.

Bipolar disorder has two sets of symptoms at opposite ends of a spectrum: manic and depressive. A diagnosis generally requires at least five symptoms lasting longer than a week at a time. Bipolar disorder is hard to manage on its own; combined with the reduced impulse control of ADHD, it can be dangerous. If you have ADHD and recognize the symptoms below, it's important to talk to your doctor so you can get an accurate diagnosis as soon as possible.

Manic symptoms:

• Severe mood changes – either extremely irritable or overly silly and elated
• Overly inflated self-esteem, grandiosity
• Increased energy
• Going with very little or no sleep for days without tiring
• Talking too much and too fast, changing topics too quickly, or being hard to interrupt
• Distractibility, with attention moving constantly from one thing to the next
• Hypersexuality – more sexual thoughts, feelings, or behaviors; explicit language
• More goal-directed activity or physical agitation
• Disregard for risk; taking on risky behaviors or activities

Depressive symptoms:

• Sad or irritable mood that doesn't go away
• Loss of interest in activities they once enjoyed
• A big change in appetite or body weight
• Difficulty sleeping or oversleeping
• Physical agitation or slowing
• Loss of energy
• Feelings of worthlessness or inappropriate guilt
• Difficulty concentrating
• Recurrent thoughts of death or suicide

Oppositional Defiant Disorder (ODD)

ODD occurs in about 40% of children diagnosed with ADHD. On its own, ODD is essentially a description of a pattern of behavior toward other children and adults. Often the behavior is driven by the poor impulse control and emotional regulation that come with ADHD. There is no medication for ODD specifically, but treating the ADHD with medication and therapy frequently improves the ODD as well.

Symptoms of ODD:

• Loses temper easily or is easily annoyed
• Angry and resentful
• Hostile toward authority figures
• Refuses to comply with requests
• Deliberately annoys or upsets others
• Blames others for their own mistakes

Tic Disorders (Tourette Syndrome)

Tourette syndrome is the best known of the three types of tic disorder, and it frequently co-occurs with ADHD. Over half of children diagnosed with Tourette are also diagnosed with ADHD, and about 1 in 5 children with ADHD have Tourette or some form of tic disorder.

Tic disorders are neurodevelopmental conditions; symptoms have to begin before age 18 to meet the diagnostic criteria.

The three types of tic disorder:

• Provisional tic disorder (lasting less than a year)
• Persistent (chronic) motor or vocal tic disorder (lasting a year or longer)
• Tourette syndrome (both motor and vocal tics, numerous and frequent, lasting more than a year)

What are tics?

Tics are abrupt, quick, repeating, non-rhythmic movements or sounds. They're involuntary: a person can hold them back for a short time but ultimately has no control over them. Tics are common in childhood and usually fade by adulthood. Boys are about three times more likely than girls to develop them.

Motor tics include eye blinking, mouth opening, facial grimacing, head movements, and shoulder shrugging, or combinations of these. Vocal tics include throat clearing, coughing, sniffing, barking, snorting, repeating parts of words or phrases, or – in rare cases – blurting out obscene or inappropriate remarks.

Executive Function Difficulties

Planning, focusing attention, remembering instructions, and juggling multiple tasks are all executive-function skills. Executive dysfunction, which gets in the way of goal-directed behavior, affects up to 90% of children with ADHD.

Broadly, executive functioning is the set of mental abilities that direct action, manage behavior, and help us work toward goals and plan for the future. People with executive dysfunction struggle to organize and regulate their behavior in the ways that would help them reach longer-term goals.

ADHD and executive functioning are closely related but not the same thing. ADHD is a formal diagnosis; "executive function difficulties" is not. Someone with executive-function difficulties on their own is usually just behind in prefrontal-cortex development and tends to be less impulsive than someone with ADHD.

Seven major types of self-regulation tied to executive functioning:

• Self-awareness – directing attention at yourself
• Self-restraint – inhibiting yourself
• Non-verbal working memory – holding things in mind to guide behavior
• Verbal working memory – retaining internal speech
• Emotional self-regulation – using words, images, and self-awareness to change how you feel about things
• Self-motivation – getting yourself to do things when there's no external consequence
• Planning and problem solving – finding new approaches and solutions

You can measure your own executive function across six areas with the Executive Function Self-Assessment.

Motor Difficulties (Dyspraxia)

People with ADHD don't only have trouble managing attention and behavior – they also tend to have more trouble controlling certain movements. Studies show that both children and adults with ADHD are more likely to have fine-motor impairments.

In one study, children with and without ADHD were asked to perform a simple motor task with one hand. The children with ADHD were more likely to involuntarily mirror the movement with the other hand, showing reduced coordination control between left and right – something researchers call "excessive mirror overflow."

This kind of fine-motor impairment is also called dyspraxia. Dyspraxia can affect:

• coordination, balance, and movement
• learning new skills, thinking, and remembering information at work and home
• daily living skills, such as dressing or preparing meals
• writing, typing, drawing, and grasping small objects
• functioning in social situations
• managing emotions
• time management, planning, and personal organization

You'll notice some of these overlap with ADHD. That's because many motor skills are governed by the same region of the brain that ADHD affects.

Language Disabilities

Language disabilities are among the most common comorbidities with ADHD. Studies show people with ADHD are about three times more likely to have some form of language disability than people without ADHD.

Language disorders can show up in a lot of different ways, including difficulty with:

• Vocabulary
• Grammar
• Narrative skills
• Reading and writing
• Expression (speaking)
• Reception (understanding)
• Social communication

Learning Disabilities

ADHD is not a learning disability, but it does make learning harder – it's tough to learn when you can't sit down with a book or stay focused on what a teacher is saying. Paired with an actual learning disability, it creates real difficulty for children and adults who are already struggling.

Some examples of learning disabilities:

• Dyslexia – reading disorder
• Dyscalculia – math disorder
• Dysgraphia – writing disorder
• Dysphasia / aphasia – problems with language
• Auditory processing disorder
• Visual processing disorder

Any of these is hard on its own, and combined with ADHD, harder still. Many of them can also produce behavior that looks a lot like ADHD, which makes them easy to miss – especially if you've already been diagnosed with ADHD. If you suspect one of these, it's worth raising with your doctor or therapist. You may need a referral to a specialist, but the sooner you know, the sooner you can start getting support.

Obsessive-Compulsive Disorder (OCD)

At first glance OCD and ADHD look like opposites. In fact they share a lot of the same wiring in the prefrontal cortex – specifically the parts that handle shifting attention, flexibility, habits, and goal-directed behavior. Those systems shape how we make decisions, remember things, plan, and move our focus from one thing to another.

Even though both conditions involve the same neural pathways, they pull in opposite directions, and that contradiction is why some researchers still argue the two can't co-exist. How can a person be overly cautious and inhibited while also being reckless and uninhibited? Brain scans reflect the same split: people with OCD tend to show excessive prefrontal-cortex activity (hypermetabolism), while people with ADHD tend to show reduced activity (hypometabolism).

Anxiety

Between 25% and 40% of people with ADHD may also have an anxiety disorder. Around 10% of people originally diagnosed with an anxiety disorder are later diagnosed with ADHD.

Common symptoms of an anxiety disorder (symptoms also seen in ADHD are noted):

• Difficulty controlling feelings of worry
• Feelings of powerlessness
• Restlessness, twitching, or tense muscles
• Increased heart rate
• Fatigue (also common in some ADHD presentations)
• Irritability or edginess
• Trouble concentrating (also common in ADHD)
• Sleep difficulties (also common in ADHD)
• Trouble breathing, or an inability to stay in confined spaces
• Panic attacks – intense fear, dizziness, heart palpitations, or shortness of breath

If you think you might have an anxiety disorder, it's important to bring it up with your doctor or therapist.

Depression

Depression and ADHD can go hand in hand, tangling together in a way that blurs the line between where one diagnosis ends and the other begins. Up to 30% of children diagnosed with ADHD are also diagnosed with depression.

"Major depression" is clinically defined as a deep sense of sadness and despair lasting more than two weeks. Another type that commonly co-occurs with ADHD is persistent depressive disorder, also called dysthymia, diagnosed when symptoms last two years or more.

Symptoms (those also seen in ADHD are noted):

• Persistent sad, anxious, or "empty" mood
• Feelings of hopelessness or pessimism (common in ADHD)
• Irritability, frustration, or restlessness (common in ADHD)
• Feelings of guilt, worthlessness, or helplessness (common in ADHD)
• Loss of interest or pleasure in hobbies and activities (sometimes caused by internalized hyperactivity in ADHD)
• Decreased energy, fatigue, or feeling "slowed down" (sometimes follows periods of hyperfocus in ADHD)
• Difficulty concentrating, remembering, or making decisions (common in ADHD)
• Difficulty sleeping, early-morning waking, or oversleeping (common in ADHD)
• Changes in appetite or unplanned weight changes
• Aches, pains, headaches, cramps, or digestive problems with no clear physical cause that don't ease with treatment
• Thoughts of death or suicide, or suicide attempts

If you or someone you know is in immediate distress or thinking about self-harm, call or text 988 to reach the 988 Suicide & Crisis Lifeline (US), or chat at 988lifeline.org. In an emergency, call 911.

Getting a clear picture

Many of these conditions share symptoms with ADHD, which is a big part of why getting an accurate diagnosis can be so hard – and why it matters to work with someone who evaluates the whole picture rather than the first thing that fits. A thorough ADHD evaluation is designed to rule other conditions in or out. You can read about what that process looks like on the ADHD Info page, and find directories and assessment services on the ADHD + Autism Resources page.

Want to talk it through? Book a free discovery call