Key points
- Trouble concentrating is a symptom, not a diagnosis. Anxiety, depression, poor sleep, chronic stress, substance use, some medications and some medical conditions can all cause it.
- Two different things can be true: another condition can look like ADHD, or it can occur alongside ADHD. Adults with ADHD commonly have at least one other condition.
- What usually separates ADHD from look-alikes is timing and pattern: ADHD symptoms begin in childhood and are present across settings, rather than starting with a stressful period or a mood episode.
- Getting the picture right matters for treatment. Some conditions change which medications are safe or which problem should be treated first.
- This page explains overlap in general terms. It cannot tell you which condition you have. That takes a comprehensive evaluation.
Why so many conditions look like ADHD
Attention, memory, motivation and organization depend on the brain working reasonably well overall. Anything that strains it, from a sleepless month to a depressive episode, can produce forgetfulness, distraction and unfinished tasks. That is why a list of symptoms, or an online checklist, cannot distinguish ADHD from everything else.
Clinicians approach this question in two ways at once:
- Look-alike. Is something other than ADHD fully explaining the symptoms? If so, treating that condition should improve attention.
- Co-occurrence. Is ADHD present and something else too? Large surveys have found that adult ADHD is often accompanied by anxiety, mood and substance use disorders, so finding one condition does not rule out another.
A diagnosis of ADHD requires, among other things, that the symptoms are not better explained by another mental disorder. Working through that question is a core part of an adult ADHD evaluation.
The clues clinicians look for
No single clue settles the question, but together these help separate ADHD from its look-alikes:
- When it started. ADHD begins in childhood, with several symptoms present before age 12, even if they were not recognized at the time. Problems that began in adulthood, after a clear change in life or health, point toward other explanations.
- Whether it is constant or comes and goes. ADHD is a long-standing trait-like pattern. Symptoms that appear in episodes, lasting weeks or months, suggest a mood or anxiety disorder.
- Where it shows up. ADHD affects more than one area of life, such as work, home and relationships. Difficulty confined to one situation needs a different explanation.
- What drives the distraction. Someone with ADHD may drift away from a task even when calm; someone with anxiety may be pulled away by worry. The reason attention slips is often revealing.
- Sleep, substances and health. These are checked routinely because they are common and treatable causes of poor concentration.
ADHD and anxiety
Anxiety and ADHD are among the most commonly confused conditions, and they frequently occur together. Both can cause restlessness, trouble concentrating, difficulty sleeping and a sense of being overwhelmed. Untreated ADHD can also create anxiety: years of missed deadlines and forgotten commitments make worry a reasonable response.
| More typical of ADHD | More typical of anxiety | |
|---|---|---|
| Onset | Childhood, often noticed at school | Can begin at any age, often during stress |
| Why attention drifts | Interest fades or something more stimulating appears | Worry or fear pulls attention away |
| Restlessness | Physical fidgeting or a need for stimulation | Tension, being on edge, feeling keyed up |
| When calm and safe | Attention problems usually persist | Concentration often improves |
| Relationship to deadlines | Pressure can help focus, at the last minute | Pressure usually makes thinking harder |
These are tendencies, not rules, and many adults have features of both. When both are present, the order of treatment is a clinical decision, since some ADHD medications can increase anxiety in some people while treating ADHD can also reduce anxiety that grew out of it. Read more in ADHD and anxiety in adults.
ADHD and depression
Depression slows thinking, drains motivation and makes concentration hard, so it can closely resemble the inattentive side of ADHD. The key differences tend to be mood and course: depression brings persistent low mood or loss of interest, often with changes in sleep, appetite and energy, and it usually has a beginning that can be dated. ADHD-related difficulties are lifelong and do not depend on mood.
The two also occur together. Adults whose ADHD went unrecognized for years often describe demoralization after repeated setbacks. Treating ADHD alone will not resolve a significant depression, and treating depression alone will not resolve ADHD, so both need to be identified.
Chronic stress and burnout
Long-term stress affects memory, focus and emotional control. A demanding job, caregiving, financial strain or a major life change can leave anyone forgetful, scattered and short-tempered. The main question is whether the difficulties predate the stress. If you were organized and focused until a particular period of your life, stress is the more likely explanation.
For adults with ADHD, stress often unmasks the condition. Coping strategies that worked with fewer responsibilities stop working after a promotion, a move or a new baby. Burnout can then follow from the extra effort needed to keep up. See ADHD and chronic stress and ADHD and burnout.
Sleep problems and sleep disorders
Poor sleep impairs attention in everyone, and sleep problems are common in adults with ADHD. The relationship runs both ways, which is why sleep is always part of an evaluation. Conditions worth knowing about include:
- Obstructive sleep apnea. Repeated pauses in breathing during sleep can cause daytime sleepiness, poor concentration and irritability. Loud snoring, gasping at night, morning headaches and unrefreshing sleep are reasons to ask about it.
- Delayed sleep phase. A body clock that runs late makes it hard to fall asleep before the small hours and hard to function in the morning. It is often reported by adults with ADHD.
- Insomnia and insufficient sleep. Whether caused by worry, screens, shift work or a busy mind, chronic short sleep produces ADHD-like symptoms on its own.
- Restless legs. An urge to move the legs in the evening can disrupt sleep.
Treating a sleep disorder can substantially improve daytime attention, and it also affects which ADHD medications and dose timings make sense. More in ADHD and sleep problems in adults.
ADHD and autism (AuDHD)
ADHD and autism can occur together. Before 2013 the diagnostic manual did not allow both diagnoses at once, so many adults now in their thirties and beyond were assessed for only one. The co-occurrence is sometimes called “AuDHD.”
The two overlap in areas such as attention, sensory sensitivity, social difficulties and executive function, but for different underlying reasons. For example, someone may miss social cues because of inattention (more typical of ADHD) or because social communication works differently for them (more typical of autism). Expert consensus guidance recommends that clinicians consider both conditions and use a structured assessment when there are signs of each.
Autism assessment is a specialized process. If autism is a question for you, ask whether it is assessed directly or by referral. See ADHD and autism in adults.
Bipolar disorder: why assessment comes first
Bipolar disorder can share features with ADHD, including restlessness, fast talking, impulsivity, distractibility and irritability. The difference is that in bipolar disorder these come in distinct episodes that are a clear change from a person's usual self, often with a reduced need for sleep and elevated or irritable mood, and usually alternate with periods of depression. ADHD is a steady, lifelong pattern.
This distinction matters for safety. Stimulant medications and some antidepressants can trigger or worsen manic symptoms in people with bipolar disorder. That is why a clinician will ask about past mood episodes, periods of unusually little sleep, and family history of bipolar disorder before recommending ADHD medication.
Trauma and post-traumatic stress
Trauma can cause hypervigilance, difficulty concentrating, poor sleep, irritability and emotional reactivity, all of which overlap with ADHD. Adults with ADHD may also have experienced more adversity. A clinician will ask about difficult experiences carefully, and you can share as much or as little as feels manageable. When post-traumatic stress is present, it generally needs its own treatment.
Substance use, medications and medical conditions
Several causes of poor concentration are easy to overlook:
- Alcohol, cannabis and other substances. Regular use, and withdrawal, affect attention and memory. Some adults with undiagnosed ADHD use substances to cope with restlessness or stress, which complicates the picture. Honest discussion helps the clinician choose safe treatment and is handled confidentially.
- Medications. Some sedating antihistamines, sleep aids, pain medications, anti-seizure medications and others can dull concentration. Bring a full list, including supplements.
- Medical conditions. Thyroid disorders, anemia, vitamin deficiencies, head injuries, hearing loss and some neurological conditions can cause symptoms that resemble ADHD. A recent checkup with your primary care clinician can help rule these out.
- Caffeine and energy drinks. Heavy use can increase restlessness and disrupt sleep, feeding the very problems it is used to fix.
Why a comprehensive evaluation matters
A careful evaluation does more than confirm or rule out ADHD. It builds a full picture: your childhood and current symptoms, mood, anxiety, sleep, substance use, health and medications. From that, a clinician can tell you whether ADHD is present, whether something else explains the difficulties better, or whether several things are happening at once.
That full picture shapes treatment in practical ways:
- Which condition to address first when several are present
- Which medications are appropriate, and which to avoid
- Whether a referral is needed, for example to a sleep specialist or your primary care clinician
- Which non-medication approaches are most likely to help
You do not need to arrive knowing the answer. It is enough to describe what is hard and how long it has been that way. For what the process involves, see the evaluation and diagnosis hub.
Guides in this hub
- ADHD and Anxiety in Adults: How to Tell Which One You Actually Have
ADHD and anxiety can share similar symptoms. Learn how their symptoms differ and why accurate evaluation matters for adults.
- Is It ADHD or Anxiety? How Psychiatrists Tell the Difference
Confused about ADHD or anxiety symptoms? Learn how psychiatrists tell them apart, why they overlap, and when to seek an evaluation.
- ADHD and Chronic Stress: How Long-Term Stress Mimics and Worsens Adult ADHD Symptoms
Learn how chronic stress and ADHD symptoms can interact and why persistent difficulties may deserve closer evaluation.
- ADHD and Autism in Adults: What Is AuDHD and How Does a Psychiatrist Diagnose Both?
Learn about AuDHD in adults, the overlap between ADHD and autism traits and why comprehensive evaluation can be important.
- ADHD and Sleep Problems: Why Adults Struggle to Fall Asleep and Stay Rested
Learn why adults with ADHD often struggle with sleep, common sleep disorders, causes, symptoms, and effective treatment options for better rest.
Questions
Can you have ADHD and anxiety at the same time?
Yes. The two commonly occur together. Sometimes long-standing ADHD contributes to anxiety, and sometimes they are independent. An evaluation looks at both and helps decide how to approach treatment.
My concentration only got bad recently. Could it still be ADHD?
ADHD begins in childhood, but it is often recognized only later, when demands increase. If you truly had no difficulties before a recent change, other explanations such as stress, sleep, mood or health are more likely. A clinician can help sort out which applies.
Can depression cause ADHD symptoms?
Depression can cause poor concentration, low motivation and forgetfulness, which can look like ADHD. The difference is usually in mood and timing: depression tends to have a dated beginning, while ADHD is lifelong.
Why does my psychiatrist ask about sleep and substance use?
Both are common and treatable causes of attention problems, and both affect which treatments are safe. The questions are routine and help avoid a wrong diagnosis.
Should I stop my other medications before an evaluation?
No. Do not stop or change any medication without talking to the clinician who prescribed it. Bring a complete list to the evaluation instead.
Sources
- National Institute of Mental Health. Attention-Deficit/Hyperactivity Disorder.
- American Psychiatric Association. What is ADHD?
- Kessler RC, et al. The prevalence and correlates of adult ADHD in the United States: results from the National Comorbidity Survey Replication. Am J Psychiatry, 2006.
- Faraone SV, et al. The World Federation of ADHD International Consensus Statement: 208 evidence-based conclusions about the disorder. Neurosci Biobehav Rev, 2021.
- Young S, et al. Guidance for identification and treatment of individuals with ADHD and autism spectrum disorder based upon expert consensus. BMC Med, 2020.
- National Institute for Health and Care Excellence (NICE). Attention deficit hyperactivity disorder: diagnosis and management (NG87).
- MedlinePlus. Attention Deficit Hyperactivity Disorder.
- 988 Suicide & Crisis Lifeline.
