**3. Three empirical studies about ADHD and writing**

The prevalence of the ADHD is high; between 3 and 6 per cent of all school age children present with it (Jakobson & Kikas, 2007). Other research studies have reported even higher percentages and state that up to 5 to 10 per cent of school age children have ADHD (Frazier, Youngstrom, Glutting, & Watkins, 2007). With these facts and considering the education system, it must be borne in mind that there is at least one child in each classroom that has a diagnosis of ADHD (Barkley, 2007). Considering the high prevalence and the large coincidence as well as the fact that people with ADHD show a lack of control of their impulses, it is probable that this will reflect in their written compositions and its learning disabilities.

Therefore, the need and relevance of furthering the research as regards the coincidence between ADHD and LD is evident. Given that few researchers have tried to identify the relationship between the various and frequently occurring subtypes that present in students with ADHD and writing learning disabilities, we aim to further the research in this area (Gregg et al*.*, 2002). In addition, it would be important to discover whether if the link between ADHD and writing LD can be considered as relationship of comorbidity, and also whether the problems that this group presents are more serious that the sum of the problems related to working memory, attention and writing that each group presents separately.

In this chapter, the theoretical element attempts to focus the aims and hypothesis of the empirical research about ADHD and writing LD, and therefore includes the pertinent and immediate antecedents. We carried out a review of the empirical studies on ADHD and writing from recent years. The primary conclusions established the deficit of empirical studies related to writing and ADHD. To be more exact, the deficit is even more obvious when the written composition is considered in relation to the processes followed by ADHD students and the written products they construct. The only studies that have been carried out only face the problem in a superficial way, without entering in detail.

It is predictable that we can achieve some understanding about the problem that these people face by doing research into composition written, but we also need more specific and in-depth research studies. Furthermore, there is a lack of research, from an educational perspective, regarding the coincidence of ADHD and composition writing. At the same time, there are also theories that consider the relationship between writing and ADHD, and this could lead to the creation of a specific model which accounts for both aspects, as a first step in future research (Rodríguez et al., 2009a; 2009b)

This research line exampled in this chapter would be both important and relevant, as it is a study into ADHD and writing LD covering the various aspects which link these disorders using various research designs. In the first place, children with normal development (cuasiexperimental study in attention and writing) are the subject. Secondly, ADHD children both with and without writing LD and without both problems, in attention, writing revision and working memory measurements (first comparative study) are the aim of investigation, and finally the attention is given to the writing product, processes and its orchestration (second comparative study).
