The purpose of this study is to investigate the familial response to Methylphenidate treatment (Ritalin IR) in two aspects: ADHD symptom's improvement and side-effects development.

Attention Deficit/Hyperactivity Disorder (ADHD) is very prevalent and tends to continue from childhood to adult life. It's heritability is 76%. It was found that there is a greater ADHD prevalence in first-degree families of ADHD subjects- 4-6 times more than the general population.

Pharmacological treatment is the first line treatment today in ADHD, in children and adults, and Methylphenidate (specially Ritalin IR) is the first medication given for the disorder.

The study includes couples of first-degree family members, both diagnosed with ADHD. Subjects will receive Ritalin IR for 4 weeks and undergo several psychiatric and cognitive questionnaires at each time of the follow-up meeting (a total of 3).

Inclusion Criteria:

• couples of first-degree family members, both diagnosed with ADHD (any type or ADHD-NOS) and need medical treatment.

Exclusion Criteria:

• subjects who receive other psychiatric medications: antipsychotic medications, antidepressants medications, anti-anxiety medications or mood stabilizers.
• people who suffer from psychotic disorder, bipolar disorder or other severe psychiatric disorders which are not stabilized.
• Alcohol/drugs addicted.
• people with chronic neurologic diseases.
• people with Autism or mental retardation.
• people with congenital heart defect.
• people with hypertension/tachycardia (>100 bpm).
• pregnancy or breast feed women.