Core Symptoms of ADHD
The following three core symptoms are characteristic of ADHD:
Hyperactivity:
Marked restlessness that shows through constant fidgeting, shifting in the chair, or climbing. For example, repeatedly tapping the foot, drumming fingers, or avoiding situations that require sitting still for a longer time.
Attention Deficit (Impaired Concentration):
Difficulty focusing attention, short attention span, and being easily distracted. This may appear as forgetfulness, careless mistakes, trouble following instructions, or starting new tasks before finishing the previous ones.
Impulsivity:
Acting or speaking without considering the consequences. This often shows as interrupting others, making hasty decisions, being more prone to accidents, ignoring rules, or sudden outbursts of anger.
However, the intensity of these symptoms can vary, and not all of them need to be present at the same time.

As individuals grow older, the ADHD symptoms often become less pronounced compared to the earlier stages of childhood and adolescence.
Additional Symptoms in ADHD
The core symptoms of ADHD – inattention, hyperactivity, and impulsivity – rarely occur alone. Often, affected children with ADHD have other problems that can change as they age. Unpleasant experiences and negative interactions occur more frequently between parents, teachers and the child or adolescent. Most commonly, children and adolescents with ADHD also exhibit oppositional and aggressive behaviours.
Conflicts with parents, teachers and peers
A variety of children and adolescents with ADHD are often rejected by their peers. This can happen because they constantly disrupt play due to their ADHD symptoms or because their aggressive behaviours are perceived as bullying.
Due to the frequently socially inappropriate behaviours of children and adolescents with ADHD, parents often have increased conflicts with their child, and the relationships between parents and child are often highly strained.
Oppositional and aggressive behaviour
Most commonly, children and adolescents with ADHD also exhibit oppositional and aggressive behaviours. These behaviours include not following important rules in the family, kindergarten, and school. Additionally, they do not respond to instructions from adults, often have outbursts of anger, and engage in frequent conflicts with siblings and other children.
In adolescence, it can occur that individuals with ADHD disregard important social rules. This can lead to various behaviours: some lie to gain advantages, some steal within or outside the family, or they skip school and stay out later at night than allowed. As a result of theft or property damage, individuals with ADHD often eventually come into conflict with the law.
Tics
Motor tics are sudden, involuntary movements such as eye blinking, nose twitching, or jerking of the head. Vocal tics are involuntary vocalizations, such as throat clearing, or even words and phrases that are suddenly spoken out. Such tics occur more frequently in children with ADHD, often starting in childhood and persisting into adolescence and adulthood.