The use of working memory training for working memory deficiencies

Previous research has shown that WMT leads to improvements in WM not only in typically developed individuals, but also leads to improvements in individuals with ADHD (Klingberg, Forssberg, and Westerberg, 2002), strokes (Westerberg et al. 2007), multiple sclerosis (Vogt, Kappos, Calabrese, Stöcklin, Gschwind & Opwis et al., 2009), acquired brain injuries (Lunqvist, Grundström, Samuelsson & Rönnberg, 2010), adolescents with a history of extremely low birth weight (LØhaugen, Antonsen, Haberg, Gramstad, Vik & Brubakk et al., 2011), adolescents with intellectual disabilities (Van der Molen et al., 2010), and children with cochlear implants

(Kronenberger, Pisoni, Henning, Colson & Hazzard, 2011).

WM was thought to be a fixed cognitive ability, which could not be improved (Engle et al., 1999; Kyllonen & Christal, 1990; Klingberg, 2010), however, studies have found that training on WM exercises improve working memory. The study by Thorell, Lindqvist, Nutley, Bohlin & Klingberg (2009) showed that WM has an effect in four- and five-year olds following a WMT for 15 minutes a day five days a week for five weeks when compared to a control group, which played computer games for the same amount of time. Moreover, in a study by Klingberg Fernell, Olesen, Johnson, Gustafsson, Dahlstrom, et al. (2005) where they looked at the effects of WMT on 53 children with ADHD, aged seven to 12 years. Participants were randomly assigned to use either the treatment computer program for training WM or a comparison program, their findings demonstrated that WM can be improved by training in children with ADHD. In another study by Olesen, Westerberg & Klingberg (2004), participants practiced 90 trials per day for 20, 24 and 30 days, respectively, on three WM tasks. Participants were scanned inside an fMRI scanner before and after training. They found that training significantly improved performance and they found training-induced increases in brain activity in the prefrontal cortex, which was related to working memory.

Despite the promising results WMT has shown in some studies, it has demonstrated unreliable results. The study by Garavan, Kelley, Rosen, Rao and Stein (2000) for instance has found that WM practice for a total of 2 hours and a total of 8 hours lead to improved response times, but not

improved accuracy on WM tasks. Additionally, while studies have found improvement in WM performance after explicit training, it was largely domain specific, with no success in finding transfer effects (Butterfield, Wambold, & Belmont, 1973; Ericcson, Chase, & Faloon, 1980). WMT has showed in some cases to not have effect on WM, for example the study by Elliott, Gathercole, Alloway, Holmes & Kirkwood (2010), where they found that WMT that modified and reducing WM load, encouraging memory-aid strategies, and used direct instruction strategies to improve WM skills, did not lead to any improvements in WM. In another study, following a 6-week training program involving online, computerized tests of short-term memory, attention, visuospatial

processing, and mathematics, participants WM did not improve compared to the control group (Owen, Hampshire, Grahn, Stenton, Dajani, & Burns et al., 2010).

There also has been studies showing that WMT only has temporary short-term effects, such as the meta-analysis by Melby- Lervåg & Hulme (2013) which reviewed WMT and found that memory training programs appear to produce short-term, specific training effects that do not generalize. Their findings cast doubt on both the clinical relevance of WMT programs and their utility as methods of enhancing cognitive functioning in typically developing children and healthy adults.

While findings have been inconsistent regarding the effects of WMT, a recent meta-analysis by Sala and Gobet (2017) focused on the effects of WM training on cognitive and academic skills in

typically developing children, aged three to 16. Their finding suggests that WM training is

ineffective at enhancing TD children’s cognitive or academic skills and that, when positive effects are observed, they are modest at best. It is well known that individuals who are trained on cognitive tasks improve their performance on those cognitive tasks (Ball et al., 2002), but because the specific task often has little relevance to everyday life, the training technique is not considered a success unless there are corresponding improvements in real-world abilities.

5.1.3 The use of medication for working memory deficiencies

The other common WM treatment is medication. In extreme cases with memory and attention deficit, pharmacologic therapies such as antidepressants and antipsychotics are recommended (Oswald et al., 2007). Many previous studies have documented that psychostimulant medication can improve WM functioning (Holmes, Gathercole, Place, Dunning, Hilton & Elliott, 2010; Barnett, Maruff, Vance, Luk, Costin & Wood et al., 2001; Tannock, Ickowicz & Schachar, 1995; Mehta, Goodyer & Sahakian, 2004; Bedard, Martinussen, Ickowicz & Tannock, 2004). In a study by Wong and Stevens (2012), they looked at the effect of psychostimulant (e.g., methylphenidate or

dextroamphetamine/amphetamine combination) in eighteen ADHD individuals, ages 11-17, on working memory. Their findings suggest that psychostimulant medication has widespread effects on the functional connectivity of frontoparietal brain networks, which might be a mechanism that underlies their beneficial effects on WM performance. Moreover, the meta-analysis by Ilieva, Hook and Farah (2015) looked at the magnitude of the effects of methylphenidate and amphetamine on cognitive functions, they found small but significant stimulant enhancement effects on inhibitory control and short-term episodic memory.

However, while medication has demonstrated significant WM improvement, there has been studies showing no difference in performance between the medicated children with ADHD and the control on a spatial WM task (Barnett, Maruff, Vance and Luk, 2001). Additionally, medication may cause adverse effects such as nausea, drowsiness, dry mouth, agitation, behavioural activation, and sleep problem (Oswald et al., 2007) decreased libido, sedation or insomnia, vomiting, and diarrhoea (Khawam, Laurencic and Malone, 2006), in addition to the period of trial and error of finding the best medication for patients. Bringing us back searching for more effective treatment options.

While both pharmacological and non-pharmacological approaches have shown positive results, both are far from leading to a significant improvement in WM in patients with ASD. In the last 15 years, there has been a growing interest in the use of non-invasive brain stimulation methods such as transcranial direct current stimulation (tDCS) as a way of improving WM in typically developed individuals and in clinical populations.