8.- PRESUPUESTO PARA CONOCIMIENTO DE LA ADMINISTRACIÓN

A range of attentional processes have been examined in children with NF1 including:

sustained attention or an inability to maintain concentration over an extended period

(Mirsky, Pascualvaca, Duncan, & French, 1999); divided attention or the ability to attend to two different stimuli presented concurrently (Cooley & Morris, 1990);

attentional control or switching attention from one task to another (Mirsky et al.,

1999); and selective attention or ignoring irrelevant stimuli (Cooley & Morris, 1990).

Difficulties with sustained attention have been well-documented in children with NF1. Weaknesses have been observed on the TEA-Ch compared to controls and normative data (Hyman et al., 2005; Isenberg et al., 2013; Payne et al., 2012; Payne, Barton, et al., 2013; Payne et al., 2011). Also continuous performance tests (CPT) of sustained attention such as the Conners CPT (Conners, 2000) and the Test of

Variables of Attention (Leark, Greenberg, Dupuy, Kindschi, & Corman, 1996) have revealed difficulties with inattention and also impulsivity (Ferner et al., 1996; Hyman et al., 2005; Isenberg et al., 2013; Mautner et al., 2002; Mazzocco et al., 1995).

Results from the TEA-Ch have also indicated weaknesses in divided attention

(Hyman et al., 2005, 2006; Isenberg et al., 2013; Payne et al., 2011; Pride et al., 2012) and switching attention or attentional control (Hyman et al., 2005) (Payne et al., 2011; Pride et al., 2012). While selective attentional problems have also been reported in NF1 (Ferner et al., 1996; Payne et al., 2011; Pride et al., 2012) this is not a

consistent finding with some studies reporting no significant differences compared to unaffected siblings (Hyman et al., 2005) or normative data (Isenberg et al., 2013).

Children with NF1 are also at increased risk of being diagnosed with ADHD. Figures range between a third to half of all children (Lehtonen et al., 2013) which is

significantly higher than the rate of 5% reported in the general population (American Psychiatric Association, 2013). Hofman and colleagues (1994) assessed 12 families with NF1 and found that four out of 12 children met the criteria for ADHD. While another study found that ADHD was diagnosed in 42% of children with NF1,

compared to only 13% of their unaffected siblings (Koth, Cutting, & Denckla, 2000). Similarly, Mautner and colleagues (2002) reported that 49.5% of children with NF1 (n = 93) assessed had ADHD. Other more recent studies have reported rates of ADHD ranging from 31% (Pride et al., 2012) to 42% (Isenberg et al., 2013). The variance in numbers of children diagnosed with ADHD most likely relates to the fact that

different criteria is used across studies and many studies employ less formal means of diagnosis (Lehtonen et al., 2013).

ADHD is typically characterised by significant difficulties related to inattention and hyperactivity/impulsivity. The DSM-5 (American Psychiatric Association, 2013) specifies three subtypes of ADHD: 1) primarily inattentive; 2) primarily

hyperactive/impulsive or 3) combined inattentive and hyperactive/impulsive. One study reported that the majority of children with NF1 and ADHD fit the combined subtype (65%), a smaller percentage fit the inattentive (32%) subtype and very few the hyperactive-impulsive (3%) subtype (Hyman et al., 2005). These results were supported by Pride et al. (2012) who also found that the combined subtype (52%) was most common, followed by the inattentive subtype (35%). A much smaller percentage fit the hyperactive-impulsive subtype (13%) (Pride et al., 2012). In addition, ADHD tends to occur equally in boys and girls with NF1 (Hyman et al., 2005). This is in

contrast to the rates observed in the general population, where there is a much higher incidence of male versus female patients (approximately 2.28:1)(Ramtekkar,

Reiersen, Todorov, & Todd, 2010).

While in the general population, the symptoms of ADHD can impact on children’s academic performance (Frazier, Demaree, & Youngstrom, 2004), there have been very few studies examining this impact in children with NF1. One study conducted by Pride et al. (2012) compared the cognitive functioning and academic achievement of children with NF1 with and without ADHD to unaffected children. They found that 31% of children with NF1 met diagnostic criteria for ADHD and that these children displayed poorer performance than children with NF1 without ADHD in a range of cognitive domains including sustained attention, language and academic performance (i.e. reading, spelling, mathematics) (Pride et al., 2012). These findings suggest that attention difficulties may significantly undermine the academic performance of children with NF1 although this areas needs further exploration. This would be consistent with findings regarding children with ADHD in the general population (Frazier et al., 2004). It has been suggested that this academic underperformance of children with ADHD is partially a result of the high rates of comorbidity between ADHD and LD such as dyslexia (Willcutt & Pennington, 2000). It may also result from the high incidence of executive deficits evident in ADHD (Pennington & Ozonoff, 1996) and the behavioural symptoms associated with the disorder which may interfere with learning (Frazier et al., 2004).

While there has been extensive investigation into the attention skills of school-age children with NF1 only a few studies have examined attention in young children with NF1. Sangster et al. (2011) found that 47% of children with NF1 (n=17, aged 4 - 5

years) displayed significant attention difficulties (omissions/commissions T score >60), as measured by the Conners Kiddie CPT (K-CPT; Conners, 2001a). However, several studies have used parent-rated measures to assess attention in young children with NF1 and have reported no significant difficulties (Klein-Tasman et al., 2014; Lorenzo et al., 2010; Lorenzo et al., 2013). In contrast, Brei and colleagues (2014) reported a significant increase in ADHD symptomatology in a group of children with NF1 (4 - 6 years, n = 30). Klein-Tasman et al. (2014) suggests that contradictory results in this area likely represent the difficulty of reliably assessing attention in younger children. Assessment measures are typically more unreliable in this age group, primarily due to the variability of young children’s attention skills (Mahone & Schneider, 2012). In addition the use of motor-based assessment measures is

problematic as younger children have greater difficulty with inhibiting responses (Mahone & Schneider, 2012). Finally, there is also evidence indicating that there is greater variation in parent-rated measures of preschool children than older children (Stefanatos & Baron, 2007), indicating that parent report may be a less reliable indicator for young children. Despite the increased difficulties of reliably assessing attention skills in younger age groups (Mahone & Schneider, 2012), it is important to develop a better understanding of possible early signs of attention difficulties in young children with NF1 (Klein-Tasman et al., 2014) and when significant difficulties may emerge.

To date, there is considerable evidence indicating that school-aged children with NF1 are at significant risk of widespread attention difficulties and ADHD. A number of studies have indicated a possible relationship between attention problems and other impairments in NF1, including academic difficulties. This is an area that warrants

further investigation as impairment in academic performance is one of the most significant functional impacts of NF1. It would also be beneficial to further explore attention skills in younger children. Studies to date have primarily used parent questionnaires to assess attention in younger age groups and these may often be an unreliable means of identifying attention problems (Stefanatos & Baron, 2007). Further investigation using a combination of assessment methods (i.e. parent interview/questionnaire, observation, psychometric assessment) may produce more reliable results (Mahone & Schneider, 2012). It would also be beneficial to explore how attention skills in young children with NF1 may relate to other cognitive abilities, particularly language and early literacy skills. There is evidence in the general

population that attention problems in preschool children may interfere with the development of early literacy skills (Walcott, Scheemaker, & Bielski, 2010).