When your child is restless, easily distracted, flits from one task to another without finishing any, or explodes over the smallest things, your inner alarm bells probably go off: “Could it be ADHD?” And it’s no wonder, since Attention Deficit Hyperactivity Disorder is one of the most common. Worldwide, it’s estimated that approximately 5% of children and 2.5% of adults suffer from it, according to the DSM-5.
However, the symptoms of ADHD can be confused with those of other psychological or physical problems. Therefore, before assuming it’s an attention disorder, it’s important to broaden your perspective to see the full picture, recognizing that behavior is often just the tip of the iceberg.
The 3 Main Symptoms of ADHD
Talking about ADHD isn’t just about hyperactive children or adults who are “on the go.” It’s about people who, despite their best efforts, feel like their brain is working like a browser with a thousand tabs open, none of which are fully loaded. In fact, this disorder is characterized by a persistent pattern of inattention, hyperactivity, and impulsivity that affects daily functioning.
1. Difficulty Concentrating, a Brain with a Thousand “tabs open”
People with ADHD can start a task highly motivated and with every intention of finishing it… but they lose focus in a short time. It’s like going out for a glass of water and coming back with a watering can to water a plant. It’s not a lack of interest; it’s that they struggle to follow all the steps, remember the correct order, or stay focused. They get distracted by the slightest thing. That’s why they often make mistakes or leave tasks unfinished.
2. Hyperactivity, when the Body has no Pause Button
Hyperactivity in children manifests as constant movement in inappropriate contexts. They find it very difficult to sit still in the classroom or remain quiet in a museum. In adults, expressions of hyperactivity are more subtle, but they still exist, such as changing posture every two minutes, constantly tapping their foot in meetings, or always being busy, to the point that their activity level exhausts others.
3. Impulsivity, the Tendency to Act without Thinking
Impulsivity is another characteristic of ADHD that drives children and adults to act impulsively. They constantly interrupt conversations and are impatient. They also have difficulty delaying gratification and make hasty decisions without considering the long-term consequences. Living with impulsivity is like driving in too high a gear: permanently accelerating without paying attention to the curves in the road.
It’s not Always ADHD: 5 Disorders it’s Often Confused with
Sometimes, ADHD becomes the default explanation for almost any challenging behavior: if they run around a lot, ADHD; if they’re easily distracted, ADHD; if they get frustrated quickly, ADHD. But not all restless, absent-minded, or impulsive children have an attention disorder, even though it may sometimes seem that way.
Many children go through phases, changes, or situations that can overwhelm them, but that doesn’t mean they have a disorder. In other cases, the underlying problem is something else. That’s why it’s essential to perform what is known in clinical practice as a differential diagnosis.
1. Oppositional Defiant Disorder (ODD)
Oppositional Defiant Disorder is one of the disorders most often confused with ADHD because both tend to involve impulsivity, low frustration tolerance, emotional outbursts, and behaviors that defy rules. From the outside, it seems as if the child “doesn’t pay attention,” “doesn’t listen,” or “loses their temper over nothing.”
The key difference lies in the intention. In Oppositional Defiant Disorder, the behavior is marked by a persistent pattern of defiance, irritability, and active confrontation with authority figures. In ADHD, on the other hand, problematic behaviors usually stem from inattention or impulsivity, not from a rejection of rules. A child with ADHD wants to comply, but cannot. A child with Oppositional Defiant Disorder deliberately resists obeying or completing schoolwork, showing hostility toward authority figures, such as parents and teachers.
2. Sleep Apnea
Sleep Apnea is another common condition that is often confused with ADHD. When children experience breathing interruptions during sleep, even mild ones, they do not rest well and the brain does not receive enough oxygen. As a result, they wake up tired, but this exhaustion does not manifest as it does in adults; instead, they become hyperactive, scattered, impulsive, experience mood swings, and are unable to concentrate. In fact, children who snore, breathe through their mouths, or have interrupted sleep are 40% more likely to show hyperactivity or inattention at age 4, which increases to almost 60% at age 7. Sleep Apnea disguised as ADHD can be differentiated by paying attention to how the child sleeps.
Experts at The Airway Dentists explain that if the child snores, has pauses in breathing, sweats excessively, or moves a lot during the night, they likely suffer from sleep apnea. The good news is that you can have a sleep study done to confirm the diagnosis, and that with treatment, the symptoms usually improve significantly or even disappear.
3. Childhood Anxiety Disorder
Yes, children can also develop anxiety. And it’s very similar to ADHD because it involves restlessness, nervousness, difficulty concentrating, and even impulsive behaviors. An anxious child may also be distracted in class, but not because they can’t concentrate, but because their mind is trapped in a loop of worries, fears, and insecurities.
The differentiating factor is the origin of the distress: in anxiety, the symptoms revolve around fear (of making mistakes, not meeting expectations, abandonment by a parent, etc.), while in ADHD, attentional difficulties are constant and depend not on the emotional context but rather on external stimuli. Furthermore, a child with anxiety tends to avoid situations that trigger fear, while a child with ADHD, due to their impulsivity, often engages in risky behaviors.
4. Intellectual Developmental Disorder
Intellectual Developmental Disorder and ADHD can appear similar because children with both have difficulty following instructions, completing tasks, or maintaining concentration. From the outside, both may seem “absentminded” or “inconsistent,” creating the impression that they are not paying attention or not trying hard enough.
The difference lies in the cause. In Intellectual Developmental Disorder, the difficulties are not due to an attention deficit, but rather to overall limitations in reasoning, learning, and comprehension. Children with intellectual disabilities need more time to process information and can become easily frustrated when they don’t understand a task. In contrast, in ADHD, intellectual capacity is preserved; the problem lies in maintaining attention or regulating activity levels.
5. Nutritional Deficiencies
ADHD is a neurodevelopmental disorder, but some nutritional deficiencies can cause very similar symptoms. Iron deficiency is the most common nutritional deficiency (affecting more than 2 billion people worldwide, particularly children) and is the most studied in relation to ADHD.
It has been associated with emotional and cognitive impairment, including difficulty paying attention and concentrating, irritability, and mood swings. In fact, some studies also indicate that iron deficiency could cause or worsen ADHD symptoms, since low ferritin levels are known to affect dopaminergic neurotransmission, which is key to regulating attention and impulse control.
However, iron deficiency also causes other symptoms, such as fatigue, weakness, and depression. Therefore, before making an ADHD diagnosis, it is essential to assess nutritional status. A blood test measuring ferritin, iron, vitamin D, and B vitamins, along with a review of eating habits, can reveal nutritional deficiencies that may be causing attention problems and irritability.
Not Everything that Seems like ADHD is ADHD
Before applying a “diagnostic label,” it is important to remember that distractibility, hyperactivity, or impulsivity can have many causes, from sleep problems to anxiety.
Before making a diagnosis, it is necessary to observe, evaluate, and seek professional support to comprehensively assess all the factors that influence behavior. A good diagnosis is key to addressing each situation in the most effective and appropriate way.
While ADHD requires specific psychological strategies, other problems, such as nutritional deficiencies or sleep apnea, demand other types of specific interventions. Access to the right treatment can make a huge difference in the life of a child or adult.
References:
Fiani, D.et. Al. (2025) Psychiatric and cognitive outcomes of iron supplementation in non-anemic children, adolescents, and menstruating adults: A meta-analysis and systematic review.Neuroscience&BiobehavioralReviews; 178: 106372.
Landaas, E. T. (2016) Vitamin levels in adults with ADHD. BJPsych Open; ;2(6):377-384.
APA (2014) Manual Diagnóstico y Estadístico de los Trastornos Mentales. Madrid: Editorial Médica Panamericana.
Bonuck, K. et. Al. (2012) Sleep-disordered breathing in a population-based cohort: behavioral outcomes at 4 and 7 years. Pediatrics;129(4):e857-65.
Konofal, E. et. Al. (2004) Iron deficiency in children with attention-deficit/hyperactivity disorder. JAMA Pediatrics; 158(9): 857–860.
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