## 1 Introduction  
Attention Deficit Hyperkinetic Disorder (ADHD) is a neurobiological behavioural disorder of the child, adolescent, and adult characterized by problems of concentration, hyperactivity, and impulsivity caused by an imbalance of chemical neurotransmitters in the brain--dopamine and noradrenaline. ADHD first-line drugs are divided in psychostimulant, as Methylphenidate and Amphetamines and non-psychostimulant medications-Atomoxetine (the only representative non-psychostimulant medication approved in our country in children and adolescents). The purpose of our research was to assess the clinical evolution of patients with ADHD based on the drug treatment that is administered: psychostimulant or non-psychostimulant. Both psychostimulant--Methylphenidate, and non-psychostimulant therapy--Atomoxetine, proved to significantly improve the symptoms of attention deficit hyperkinetic disorder. There was a significant reduction in the severity of ADHD symptoms at six months and at one year from the start of treatment in the case of the psychostimulant group, whereas in the non-psychostimulant group, the significant reduction in severity of symptomatology occurs only at six months after the start of treatment. We can conclude that both types of drugs are effective in reducing the severity of symptoms and in improving the clinical condition of patients with ADHD, but the comparative analysis of the two groups demonstrated that significantly better results are obtained with psychostimulant treatment. psychostimulants; non-psychostimulants; ADHD; methylphenidate; Atomoxetine; clinical condition  
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hyperactivity, and impulsivity caused by an imbalance of chemical neurotransmitters in the brain--dopamine and noradrenaline, affecting those parts of the brain responsible for self-monitoring and for suppressing inappropriate behaviours [1; 2; 3]. At present, ADHD is a major public health problem due to its high prevalence. Currently, it is considered the most common neuropsychiatric disorder, affecting 5-10% of children and adolescents [2; 4; 5; 6]. There are theories that involve the effect of dopamine and noradrenaline neurotransmitters in the onset of ADHD. The response of patients with ADHD to psychostimulants, which facilitate dopamine release, has led to the speculation that, in some areas of the brain, these neurotransmitters have deficiencies in the transmission of nerve impulses. In children diagnosed with ADHD, imaging investigations revealed a decrease in cerebral activity in the frontal and parietal cortex and in cerebellum [6; 7; 8; 9]. The diagnosis of ADHD requires both developmentally inappropriate symptoms of inattention and/or hyperactivity and impulsivity and functional impairments in multiple settings. Functional domains affected by ADHD include academic functioning, peer relationships, and family functioning. Usually, functional impairments, rather than emerging symptoms, tend to be the primary reason for clinical referral [4; 5; 6]. The approach to the ADHD is multimodal, involving also drug therapies. Nowadays, the first-line drugs used to treat ADHD are divided in two major classes: psychostimulant and non-psychostimulant medications [6; 10]. Psychostimulants correct dopamine deficits in the central nervous system by blocking dopamine uptake mechanisms at this level in increasing the extracellular level of dopamine. There are studies that have shown that psychostimulants gradually regulate the functioning of neurons in the prefrontal cortex. The most commonly used drugs in this class are methylphenidate and amphetamines [1; 2; 5; 6]. Non-psychostimulant medications have a different mechanism to increase free norepinephrine. They make a blockage in the neuronal synapse, resulting in a relative increase of noradrenaline at this level. The benefits of non-psychostimulant medications consist in a long time action, facility of administration, requiring a single dose per day, the absence of rebound phenomena, low risk of abuse, and flexibility in dose adjustment.