Introduction

Attention deficit hyperactivity disorder (ADHD) is a disorder of childhood and adolescence characterized by a pattern of extreme pervasive, persistent and debilitating inattention, overactivity and impulsivity. It is believed to be one of the most common reasons for mental health referrals to family physicians, aediatricians,paediatric neurologists and child and adolescent psychiatrists. Although originally thought to remit during childhood, the symptoms of ADHD have also been shown to persist in patients through adolescence and into adulthood . The disorder is often chronic, with one third to one half of those affected retaining the condition into adulthood . It interferes with many areas of normal development and functioning in a child’s life. Children with ADHD are more likely than their peers to experience educational underachievement, social isolation and antisocial behaviour during the school years and to go on to have significant difficulties in the post-school years (1). Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders of childhood. The worldwide prevalence in children ≤18 years has been estimated at 5.3% in a systematic review of 102 studies from all continents, with a majority from North America and Europe (2).

Attention deficit hyperactivity disorder (ADHD) is characterized by pervasive and impairing symptoms of inattention, hyperactivity, and impulsivity according to DSM-IV (3) . The World Health Organization (WHO) (4) uses a different name—hyperkinetic disorder (HD)—but lists similar operational criteria for the disorder. Regardless of the name used, ADHD/HD is one of the most thoroughly researched disorders in medicine  . It has been associated with a broad range of negative outcomes for affected subjects  and with a serious financial burden to families and society, which characterizes it as a major public health problem.

An understanding of the epidemiological aspects of ADHD/HD may provide insight into its distribution and etiology as well as information for planning the allocation of funds for mental health services. In past decades, investigators from all regions of the world have made substantial efforts to define the prevalence of the disorder. Several literature reviews have reported highly variable rates worldwide, ranging from as low as 1% to as high as nearly 20% among school-age children. Several investigators have suggested that prevalence rates in Europe were significantly lower than rates found in North America (2).

Alternative Names

ADD; ADHD; Childhood hyperkinesis.

Symptoms

Symptoms of ADHD fall into three groups:

• Not being able to focus (inattentiveness)
• Being extremely active (hyperactivity)
• Not being able to control behavior (impulsivity)

Some people with ADHD have mainly inattentive symptoms. Some have mainly hyperactive and impulsive symptoms. Others have a combination of different symptom types. Those with mostly inattentive symptoms are sometimes said to have attention deficit disorder (ADD). They tend to be less disruptive and are more likely not to be diagnosed with ADHD.

Inattentive Symptoms

• Fails to give close attention to details or makes careless mistakes in schoolwork
• Has difficulty keeping attention during tasks or play
• Does not seem to listen when spoken to directly
• Does not follow through on instructions and fails to finish schoolwork or chores and tasks
• Has problems organizing tasks and activities
• Avoids or dislikes tasks that require sustained mental effort (such as schoolwork)
• Often loses toys, assignments, pencils, books, or tools needed for tasks or activities
• Is easily distracted
• Is often forgetful in daily activities

Hyperactivity Symptoms

• Fidgets with hands or feet or squirms in seat
• Leaves seat when remaining seated is expected
• Runs about or climbs in inappropriate situations
• Has problems playing or working quietly
• Is often "on the go," acts as if "driven by a motor"
• Talks excessively

Impulsivity Symptoms

• Blurts out answers before questions have been completed
• Has difficulty awaiting turn

Interrupts or intrudes on others (butts into conversations or games).

Different Symptoms

Boys and girls display very different ADHD symptoms, and boys are much more likely to be diagnosed with the attention disorder. Why? It’s possible the nature of ADHD symptoms in boys makes their condition more noticeable than it is in girls.Boys tend to display externalized symptoms that most people think of when they think of ADHD behavior, for example: impulsivity or “acting out”hyperactivity, such as running and hittinglack of focus, including inattentivenessphysical aggressionADHD in girls is often easy to overlook because it’s not “typical” ADHD behavior. The symptoms aren’t as obvious as they are in boys. They can include:being withdrawnlow self-esteem and anxietyintellectual impairment and difficulty with academic achievementinattentiveness or a tendency to “daydream”verbal aggression: teasing, taunting, or name-calling (Figur.1) (5-7).

Fig.1: Different ADHD symptoms in children

Epidemiology

The mean worldwide prevalence of ADHD is between 5.29% and 7.1% in children and adolescents (

Prevalence factors ADHD prevalence rates may vary depending on several factors: Age – ADHD can affect children from pre-school age2-4 and increasing recognition is now given to the fact that ADHD can extend beyond childhood and adolescence into adulthood (8, 9-12). Gender – a higher prevalence is often reported in males (8,13,14). Subtype of ADHD – combined-type ADHD is generally considered most prevalent in all age-groups (15,16). ADHD is often present alongside comorbidities such as oppositional defiant disorder (ODD) and anxiety disorder (9,16-19) which may further complicate understanding of true prevalence rates.

Africa

It is estimated that ADHD affects between 5.4-8.7% of children in Africa. Data quality however is not high(20).

Germany

A 2008 evaluation of the “KiGGS” survey, monitoring 14,836 girls and boys (age between 3 to 17 years), showed that 4.8% of the participants had an ADHD diagnosis. While 7.9% of all boys had ADHD, only 1.8% girls had it, too. Another 4.9% of the participants (6.4% boys : 3.6% girls) were suspected ADHD cases, because they showed a rate ≥7 on the Strengths and Difficulties Questionnaire (SDQ) scale. The number of ADHD diagnoses was 1.5% (2.4% : 0.6%) among preschool children (3–6 years old), 5,3 % (8.7% : 1.9%) at age 7–10 years, and had its peak at 7.1% (11.3% : 3.0%) in the age group of 11–13 years. Among 14 to 17 years old adolescents the rate was 5.6% (9.4% : 1.8%) (21). 

Spain

Rates in Spain are estimated at 6.8% among people under 18 (22).

United States

In the United States it is diagnosed in 2-16 percent of school children. The rates of diagnosis and treatment of ADHD are much higher on the east coast of the United States than on its west coast. The frequency of the diagnosis differs between male children (10%) and female children (4%) in the United States. This difference between genders may reflect either a difference in susceptibility or that females with ADHD are less likely to be diagnosed than males. Boys outnumber girls across all three subtyping categories, but the exact magnitude of these differences seems to depend on both the informant (parent, teacher, etc.) and the subtype. In two community-based investigations, conducted by DuPaul and associates, boys outnumbered girls by only 2.2:1 in parent-generated samples and 2.3:1 in teacher-based input (23-29).

Exams and Tests

If ADHD is suspected, the person should be evaluated by a health care professional. There is no test that can make or exclude a diagnosis of ADHD. The diagnosis is based on a pattern of the symptoms listed above. When the person with suspected ADHD is a child, parents and teachers are usually involved during the evaluation process.

Most children with ADHD have at least one other developmental or mental health problem. This problem may be a mood, anxiety or substance use disorder; a learning disability; or a tic disorder. A doctor can help determine whether these other conditions are present.

Treatment

Treating ADHD is a partnership between the health care provider and the patient. If the patient is a child, parents and often teachers are involved. For treatment to work, it is important to:

• Set specific, appropriate goals.
• Start medicine and/or talk therapy.
• Follow-up regularly with the doctor to check on goals, results, and any side effects of medicines. During these visits, information should be gathered from the patient and if relevant, parents and teachers.

If treatment does not seem to work, the health care provider will likely:

• Confirm the person has ADHD.
• Check for medical conditions that can cause similar symptoms.
• Make sure the treatment plan is being followed.

• Medicines
• Medicine combined with behavioral treatment often works best. There are several different ADHD medicines that may be used alone or in combination. The health care provider will decide which medicine is right based on the person's symptoms and needs.
• Psychostimulants (also known as stimulants) are the most commonly used ADHD medicines. Although these drugs are called stimulants, they actually have a calming effect in people with ADHD.
• Follow the health care provider's instructions on how to take ADHD medicine.
• Some ADHD medicines have side effects. If the person has side effects, contact the health care provider right away. The dosage or medicine itself may need to be changed (30-34).

Risk factors for ADHD include:

• Blood relatives (such as a parent or sibling) with ADHD or another mental health disorder
• Exposure to environmental toxins — such as lead, found mainly in paint and pipes in older buildings
• Maternal drug use, alcohol use or smoking during pregnancy
• Maternal exposure to environmental poisons — such as Polychlorinated biphenyls (PCBs) — during pregnancy
• Premature birth

Although sugar is a popular suspect in causing hyperactivity, there's no reliable proof of this. Many things in childhood can lead to difficulty sustaining attention, but that is not the same as ADHD (35,36).

Prevention

To help reduce your child's risk of ADHD:

• During pregnancy, avoid anything that could harm fetal development. Don't drink alcohol, smoke cigarettes or use drugs. Avoid exposure to environmental toxins, such as polychlorinated biphenyls (PCBs).
• Protect your child from exposure to pollutants and toxins, including cigarette smoke, agricultural or industrial chemicals, and lead paint (found in some old buildings).
• Limit screen time. Although still unproved, it may be prudent for children to avoid excessive exposure to TV and video games in the first five years of life.

If your child has ADHD, to help reduce problems or complications:

• Be consistent, set limits and have clear consequences for your child's behavior.
• Put together a daily routine for your child with clear expectations that include such things as bedtime, morning time, mealtime, simple chores and TV.
• Avoid multitasking yourself when talking with your child, make eye contact when giving instructions, and set aside a few minutes every day to praise your child.
• Work with teachers and caregivers to identify problems early, to decrease the impact of the condition on your child's life (2-9).