This page presents the current status of the results of the Project DyAdd.
Peer-reviewed articles

Kivisaari, S., Laasonen, M., Leppämäki, S., Tani, P., & Hokkanen, L. (2012). Retrospective Assessment of ADHD Symptoms in Childhood: Discriminatory Validity of Finnish Translation of the Wender Utah Rating Scale. Journal of Attention Disorders, 16(6), 449-459.

Laasonen, M., Hokkanen, L., Leppämäki, S., Tani, P., & Erkkilä, A. (2009). Project DyAdd: fatty acids and cognition in adults with dyslexia, ADHD, or both. Prostaglandins, Leukotrienes and Essential Fatty Acids, 81(1), 79-88.

Laasonen, M., Hokkanen, L., Leppämäki, S., Tani, P., & Erkkilä, A. (2009). Project DyAdd: fatty acids in adult dyslexia, ADHD, and their comorbid combination. Prostaglandins, Leukotrienes and Essential Fatty Acids, 81(1), 89-96.

Laasonen, M., Kauppinen, J., Leppämäki, S., Tani, P., Harno, H., Hokkanen, L., & Wikgren, J. (2012). Project DyAdd: Classical eyeblink conditioning in adults with dyslexia and ADHD. Experimental Brain Research, 223(1), 19-32.

Laasonen, M., Lehtinen, M., Leppämäki, S., Tani, P., & Hokkanen, L. (2010). Project DyAdd: Phonological processing, reading, spelling, and arithmetic in adults with dyslexia or ADHD. Journal of Learning Disabilities, 43(1), 3-14.

Laasonen, M., Leppämäki, S., Tani, P., & Hokkanen, L. (2009). Adult dyslexia and attention deficit disorder in Finland - project DyAdd: WAIS-III cognitive profiles. Journal of Learning Disabilities, 42(6), 511-527.

Laasonen, M., Salomaa, J., Cousineau, D., Leppämäki, S., Tani, P., Hokkanen, L., & Dye, M. (2012). Project DyAdd: visual attention in adult dyslexia and ADHD. Brain and Cognition, 80(3), 311-327.

Laasonen, M., Väre, J., Oksanen-Hennah, H., Leppämäki, S., Tani, P., Harno, H., Hokkanen, L., Pothos, E., & Cleeremans, A. (2014) Project DyAdd: implicit learning in adult dyslexia and ADHD, Annals of Dyslexia, 64(1), 1-33.

Master's theses

Emma Hietarinta (2007) Toiminnanohjaus ja tarkkaavuus aikuisten dysleksiassa ja tarkkaavuushäiriössä / Executive functioning and attention among adults with dyslexia or attention deficit disorder

The objectives of this study were to clarify the possible deficits in executive functioning and attention among Finnish speaking adults who have been diagnosed with dyslexia or attention deficit disorder, and to determine whether it is possible to distinguish these two developmental disorders from each other with the help of neuropsychological tests. A further objective was to scrutinize the dimensions of executive functioning and attention. The participants were adults (age 18 to 55 years) diagnosed with dyslexia (n = 34) or attention deficit disorder (n = 21) and a control group (n = 34).

Executive functioning and attention were assessed with widely used neuropsychological tests. The performance of each group was assessed in set shifting, inhibition, planning, verbal fluency, sustained attention and processing speed. In comparison with the control group, both the dyslexia and the attention deficit disorder groups were significantly impaired in inhibitory control, verbal fluency, and processing speed. These results indicate that adults with dyslexia or attention deficit disorder show similar impairments in executive functioning and attention. The impairments can be observed in the neuropsychological test data and also in the theoretical components of executive functioning and attention. This study reinforces the argument that executive functioning and attention are impaired with adults suffering from dyslexia or attention deficit disorder.

Minna Kuivalainen (2008) Työmuisti aikuisten dysleksiassa ja tarkkaavuushäiriössä / Working memory in adult dyslexia and attention deficity hyperactivity disorder

The aim of this study was to investigate working memory in dyslexia, attention deficit hyperactivity disorder (ADHD) and combined type of dyslexia – ADHD in Finnish adults. Previous studies have shown that verbal working memory is often impaired in dyslexia, but what comes to studies about visuospatial working memory in dyslexia the results have been somewhat controversial. Working memory studies concerning ADHD have also been somewhat controversial. Nevertheless, ADHD has often been linked with impaired visuospatial working memory. Verbal working memory has been shown to be similarly impaired in dyslexia – ADHD as in dyslexia alone. Yet, in previous studies there has not been clear evidence of impaired visuospatial working memory in dyslexia – ADHD. In this study working memory was assessed not only with two sum variables that reflect the overall efficiency of working memory but also by dividing working memory into verbal and visuospatial working memory. 

Hypothesis were: 1. The overall efficiency of working memory is impaired in dyslexia and in dyslexia-ADHD compared to control group.2. The overall efficiency of working memory is impaired in ADHD compared to control group. 3. The verbal working memory is impaired in dyslexia and in dyslexia-ADHD compared to ADHD and to control group. 4. The verbal working memory is impaired in ADHD compared to control group. 5. The visuospatial working memory is impaired in ADHD and in dyslexia-ADHD compared to dyslexia and to control group. 

The study consisted of 118 participants, of which 40 were in dyslexia, 30 in ADHD, 9 in dyslexia – ADHD and 39 in control group. The participants were 18 – 55 year old native Finnish speaking people. The overall efficiency of working memory was assessed with two sum variables. The sum variables were the Freedom from Distractibility Index of WAIS-III and Tulsky & Price’s (2003) working memory factor combining parts of WAIS-III and WMS-III. Verbal working memory was assessed with letter-digit spans and digit spans forward and backward. Visuospatial working memory was assessed with visual spans forward and backward and also with a spatial working memory task (SWM) of computerized CANTAB –test battery. The variables studied in letter-digit, digit and visual spans were the longest spans. 

Dyslexia group showed impaired performance in the overall efficiency of working memory compared to control group. In verbal working memory the digit span forward was shorter in dyslexia compared to control group. However, covariating intelligence the main effect of the group did not show any significance in verbal working memory. In ADHD or in dyslexia-ADHD there were no difficulties with working memory. The results of this study mainly support the previous studies that dyslexia is connected with impaired verbal working memory. However, in this study the dyslexia group did not show impaired performance in every task of verbal working memory. Regarding ADHD the results of this study support the view in which the linkage between ADHD and working memory has been questioned. In the basis of this study more useful methods in the assessment of dyslexia could be different sum variables like the Freedom from Distractibility of WAIS-III and Tulsky & Price’s (2003) working memory factor than separate memory span tasks.

Maisa Lehtinen (2008) Fonologisen prosessoinnin yhteys dysleksiaan ja tarkkaavaisuushäiriöön suomalaisilla miehillä ja naisilla / The relation of phonological processing to dyslexia and attention deficit disorder among Finnish men and women

Phonological processing comprises phonological awareness, phonological memory and rapid naming. It is related to learning to read and its difficulties. Dyslexia (reading disability) is one of the most common learning disabilities and the problems often remain throughout adulthood. People with dyslexia typically have comorbid learning disabilities, such as attention deficit disorder (with or without hyperactivity). In this study, both types of attention deficit disorders are referred as ADHD. Impairments in phonological processing are thought to be related specifically to dyslexia. Therefore, these impairments should not emerge among ADHD subjects. Both these learning disabilities are more common among boys than girls. There are a few studies concerned with the relation between phonological processing and dyslexia in Finnish adults. However, to our knowledge, there are no previous studies that would have compared dyslexia concurrently to healthy controls and to ADHD. Moreover, there are a limited amount of studies that have examined the relation between phonological processing and gender. The objective of the present study was to examine the relation between phonological processing and dyslexia among Finnish adults, when they were compared to ADHD and fluent readers. In addition, the objective was to determine if there was a main effect of gender, independent of a possible main effect of group.

There were 52 women and 56 men who participated in the present study. All the participants were in the groups of control, dyslexia or ADHD and they were Finnish adults between the ages of 18 and 55. Two tasks of phonological awareness, three tasks of phonological memory and two tasks of rapid naming were given to participants. The dyslexia group was poorer than the control group in every sub-process of phonological processing. The dyslexia group was poorer than the ADHD group only in rapid naming. The control group and the ADHD group did not differ from each other in any measure of phonological processing. Women outperformed men only in Stroop color naming. The differences in phonological memory were only indicative. The results support the previous studies that have suggested that impairments in phonological processing, especially in rapid naming, are related to dyslexia in Finnish adults. There was some support for the previous studies of women's outperforming skills in verbal tasks and in phonological processing. From the measures used in this study the following were the best in differentiating dyslexic from the healthy controls in Finnish adults: phonological awareness (Pig Latin, called as "kontinkieli", and phonological synthesis), phonological memory (digit span and letter-number sequencing) and rapid naming (Stroop color naming and RAS).

Meeri Sivonen (2008) Brown Attention Deficit Disorder Scale (BADDS- asteikko) suomalaisten aikuisten tarkkaavuushäiriön arvioinnissa / Brown Attention Deficit Disorder Scale (BADDS-scale) in evaluating ADHD in Finnish adults 

Deficits in executive functions and emotional difficulties are common symptoms of attention deficit hyperactivity disorder. Depression or dyslexia are comorbid with ADHD. Brown Attention Deficit Scale (BADDS) evaluates both executive function deficit and emotional difficulties. BADDS consists of 40 items and greater scores describe symptoms that occur more often. The five sub-scales of BADDS measure difficulties related to organizing and activating to work, sustaining attention and concentration, sustaining energy and effort, managing affective interference and utilizing working memory and accessing recall. The scale is in clinical use internationally but there is no published research on its structure or normative data outside of United States.

The aim of the current study was to examine the structure of BADDS-scale, reference values and discrimination power in Finish adults. The participants were grouped into those with ADHD (n=29), dyslexia (n=39), or healthy controls (n=40). It was hypothesized that the ADHD-group would have the highest scores in four sub-scales, but in the sub-scale of working memory and accessing recall the dyslexia-group was expected to receive the highest scores. It was also hypothesized that the ADHD group would receive highest total score and the control group the lowest.

The structure of BADDS diverged partially from the structure represented in the BADDS-manual. ADHD group had highest scores in four sub-scales but the in the scores of the sub-scale working memory and accessing recall scores ADHD- and dyslexia groups were equal. As hypothesized, the ADHD group received the highest total score and the control group the lowest. Intelligence or symptoms of depression did not explain the group differences. The most reliable cut score distinguishing the ADHD and the control group was 52. The cut score of 52 yields 96 % right positive and 92 % right negative. BADDS distinguishes the ADHD and the control group reliably and it can be used as one method when evaluating ADHD.

Sasa Kivisaari (2008) Itsearviointikyselyt nykyisten ja lapsuuden tarkkaavaisuushäiriöoireiden arvioinnissa aikuisilla / Self-rating scales in the assessment of current and childhood symptoms of attention deficit hyperactivity disorder in adults

Objective: Attention deficit hyperactivity disorder (ADHD) is a life-long condition, but because of its historical status as a self-remitting disorder of childhood, empirically validated and reliable methods for the assessment of adults are scarce. In this study, the validity and reliability of the Wender Utah Rating Scale (WURS) and the Adult Problem Questionnaire (APQ), which survey childhood and current symptoms of ADHD, respectively, were studied in a Finnish sample.

Methods: The self-rating scales were administered to adults with an ADHD diagnosis (n = 38), healthy control participants (n = 41), and adults diagnosed with dyslexia (n = 37). Items of the self-rating scales were subjected to factor analyses, after which the reliability and discriminatory power of the subscales, derived from the factors, were examined. The effects of group and gender on the subscales of both rating scales were studied. Additionally, the effect of age on the subscales of the WURS was investigated. Finally, the diagnostic accuracy of the total scores was studied. 

Results: On the basis of the factor analyses, a four-factor structure for the WURS and five-factor structure for the APQ had the best fit to the data. All of the subscales of the APQ and three of the WURS achieved sufficient reliability. The ADHD group had the highest scores on all of the subscales of the APQ, whereas two of the subscales of the WURS did not statistically differ between the ADHD and the Dyslexia group. None of the subscales of the WURS or the APQ was associated with the participant's gender. However, one subscale of the WURS describing dysthymia was positively correlated with the participant's age. With the WURS, the probability of a correct positive classification was .59 in the current sample and .21 when the relatively low prevalence of adult ADHD was taken into account. The probabilities of correct positive classifications with the APQ were .71 and .23, respectively. 

Conclusions: The WURS and the APQ can provide accurate and reliable information of childhood and adult ADHD symptoms, given some important constraints. Classifications made on the basis of the total scores are reliable predictors of ADHD diagnosis only in populations with a high proportion of ADHD and a low proportion of other similar disorders. The subscale scores can provide detailed information of an individual's symptoms if the characteristics and limitations of each domain are taken into account. Improvements are suggested for two subscales of the WURS.

Jenni Väre (2008) Implisiittinen oppiminen aikuisiän dysleksiassa / Implicit learning in adulthood dyslexia

Developmental dyslexia is defined as a failure to acquire efficient reading skills, despite conventional schooling, adequate intelligence and socio-cultural opportunity. Dyslexia is most often first diagnosed in childhood, but usually persists into adulthood. Although dyslexia is generally expected to be caused by difficulties in phonological processing, a number of associated symptoms have also been described. These include, for instance, difficulties in processing perceptual information and problems in motor coordination. Dyslexia is also often found in association with other developmental difficulties, such as ADHD. The object of the present study was to assess whether a study group of adults (age 18-55) diagnosed with dyslexia have problems in implicit learning, defined as the ability to learn without awareness. The groups compared included a dyslexia group (n=33), a control group (n=31) and a clinical control group composed of participants diagnosed with ADHD (n=20). The ADHD group was selected as the clinical control group because the frequent co-occurrence of these disorders. Because of this co-occurrence the associated symptoms of dyslexia are often thought to be explained by problems of attention. The ADHD group is an important clinical control group, given the frequent co-morbidity between dyslexia and ADHD. The groups were comparable in terms of age, sex, educational background and handedness. The performance of the groups was compared in two tasks of implicit learning: a task of serial reaction time and a task of artificial grammar learning. The performance of the subjects did not differ statistically on either of the implicit learning paradigms. Therefore, according to this study, adult dyslexia did not appear to be related to problems in implicit learning.

Jenni Kauppinen (2008) Aikuisiän dysleksian yhteys pikkuaivojen poikkeavaan toimintaan klassisen silmänräpäysehdollistamisen menetelmällä tutkittuna / The association between adult dyslexia and impaired cerebellar function: A classical eyeblink conditioning study

Developmental dyslexia (specific reading disability) is usually assumed to result from difficulties in phonological processing. However, the phonological theory is unable to explain all the symptoms of dyslexia. In addition to the reading difficulties, a dyslexic reader often has also motor and sensory problems. According to the cerebellar theory of dyslexia, mild developmental cerebellar impairment could explain at least some cases of the disorder.

In the present study, delay and trace classical eyeblink conditioning were used to compare dyslexic adults (n = 37) with healthy controls (n = 35), an ADHD group (n = 21), and a comorbid group consisting of participants with diagnoses of both dyslexia and ADHD (n = 8). A small group (n = 3) of episodic ataxia type 2 (EA2) patients were also included in qualitative analyses. They suffered from developmental cerebellar atrophy. No statistically significant differences were found between dyslexic readers and other groups in the amount or timing of conditioned responses when using the delay procedure. Furthermore, in the trace procedure, no differences between the groups were found in the amount of responses. However, the latencies of the conditioned responses of dyslexic participants were not as adaptive as those of the other groups included in the analysis. Deviant timing of the conditioned response can be associated with a cerebellar impairment.

Compared to the other groups, dyslexic participants had only mild difficulties An exception was the EA2 group that completely failed to acquire conditioned responses. This study lends partial support to the idea of cerebellar dysfunction in dyslexia. It is still unlikely that such a minor impairment could explain the wide variety of symptoms related to dyslexia, as suggested by the cerebellar theory.

Jonna Salomaa (2008) Suomalaiseen aikuisiän dysleksiaan liittyvät valikoivan näönvaraisen tarkkaavuuden vaikeudet ja niiden tietokoneavusteinen arviointi / Selective visual attention difficulties in Finnish adult dyslexia and examining these by computer-based methods

Objectives. Impaired selective visual attention has been suggested to contribute to the difficulties related to developmental dyslexia (reading disability). Previous studies have concentrated on children and on English speaking countries. The aim of the current study was to clarify, whether difficulties in selective visual attention are related also to Finnish adult dyslexia. Previously, dyslexic readers have been shown to be impaired in processing rapid stimulus sequences, which reflects slowed shifting of selective visual attention. It has also been reported that dyslexic readers have selective spatial attention difficulties. Attention deficit hyperactivity disorder (AD/HD) is another developmental disorder. It has been suggested to relate to similar problems in selective attention as dyslexia. These two developmental disorders have high comorbidity, which could have been influenced previous results on attention. The second aim of the current study was to compare Finnish adults with dyslexia or AD/HD in tasks of visual attention.

Methods. Participants were 35 dyslexic subjects, 22 subjects with attention deficit hyperactivity disorder, and 32 healthy controls. Exclusion criteria were comorbid disorders affecting cognitive functions. Three computerized tasks were used; each of them examined different skills of visual attention. First task examined processing rapid stimulus sequences, second task selective spatial attention skills and extent of useful field of view, and third task capacity of visual attention. 

Results and conclusions. Both dyslexic and AD/HD-participants were impaired in processing rapid stimulus sequences. It is proposed that their slowed shifting of visual attention was not a consequence of slowed general visual processing, deficits in attentional capacity, or short-term memory. Dyslexic participants, AD/HD participants, and controls did not differ from each others in their selective spatial attention skills or the extent of useful field of view. The groups did not differ in their capacity of visual attention, either. Thus, it was concluded that similar difficulties in selective visual attention are related to Finnish adult dyslexia and attention deficit hyperactivity disorders. The slowed shifting of selective attention is a specific difficulty related to dyslexia, and can’t be explained by comorbid AD/HD.

Mirva Reuhkala (2009) Episodinen muistisuoriutuminen aikuisten dysleksiassa ja tarkkaavuushäiriössä / Episodic Memory Functions in Adult Attention Deficit Hyperactivity Disorder and Dyslexia

Objectives: Episodic memory is a part of long-term memory that holds temporal and spatial information about personally experienced events. Regardless of the nature of the material to be learned, episodic memory functions always include processes of encoding, recall, recognition and retention. Dyslexia and attention deficit hyperactivity disorder (ADHD) are the most common developmental disorders and both usually continue into adulthood. In both disorders, most research has focused on children and working memory functions. Because symptoms of dyslexia and ADHD tend to change and remit to a degree in adulthood, the generalizability of results from childhood studies to adults is questionable. Both clinical groups have been associated with deficits in attention and working memory but it is unknown, whether deficits in encoding affect episodic memory functions. Childhood dyslexia has been linked with a deficit in verbal episodic recognition and retention and adult ADHD, respectively, with poor verbal episodic recall. The present study explored verbal and visual episodic memory functions in adults with diagnosed dyslexia or ADHD and expected to replicate previous results.

Methods: The adult participants consisted of 40 healthy controls, 40 diagnosed with dyslexia and 29 diagnosed with ADHD. Episodic recall and recognition were assessed using the WMS III (Wechsler Memory Scale III) verbal subtests of Logical Memory and Word Lists and visual subtests of Visual Reproduction. In addition, retention scores were calculated for each subtest. A repeated measures ANOVA was used to assess episodic recall in immediate and delayed situations as well as episodic recognition. Episodic retention was analyzed using multiple-analysis of variance (MANOVA).

Results and conclusions: Episodic memory functions did not differ between the study groups apart from verbal recall. The dyslexic group recalled the second story worse than the control group presumably due to its complicated language. Unlike the dyslexic and control groups, the delay did not affect the recall of word lists in the ADHD group. No deficits in visual episodic recall, verbal or visual recognition nor retention were associated with the dyslexic and ADHD groups. Episodic recognition and visual retention had not previously been studied in adult dyslexia or ADHD. It seems that episodic memory deficits are not necessarily part of adult ADHD and in adult dyslexia, difficulties may be confined to the verbal recall of linguistically complicated material. In addition, deficits in attention and working memory may not affect episodic memory functioning and the process of episodic recall, can be dissociated from episodic recognition and retention.

Arja Sarkio (2009) Voiko magnosolujen heikkous selittää kehityksellistä dysleksiaa / Does a weakness of magno cells explain dyslexia? 

Jenni Honkavaara (2011) Tarkkaavuus aikuisten dysleksiassa ja tarkkaavuushäiriössä: kaksoistehtävätutkimus / Attention in dyslexia and attention deficit disorder: a dual-task study

Objectives. The aim of the current study was to clarify the attentional difficulties related to dyslexia and attention deficit disorder (ADHD) among Finnish speaking adults. The study focused on processing speed, sustained attention and divided attention, which can all be considered to be functions related to attention. Difficulties in processing speed have previously been linked to both dyslexia and ADHD. There are controversial results about sustained and divided attention in both disorders, but more consistently these difficulties have been observed in ADHD. Dyslexia and ADHD co-occur frequently, which may have influenced previous results of attention in these disorders. Also, most previous studies have concentrated on children. This study, therefore, aims at clarifying the attentional problems particularly in adults.

Methods. There were 110 participants in this study, aged between 18?55 years. Of the participants, 29 were in ADHD, 41 in dyslexia and 40 in control group. The three aspects of attention were evaluated with a dual-task, introduced by Vilkki, Virtanen, Surma-Aho and Servo (1996). This task is used quite frequently in clinical practice in Finland, but its usefulness in differentiating these clinical disorders and healthy controls has not been studied before. The tasks in the dual-task were a verbal counting backwards and a visual cancellation task.

Results and conclusions. Both dyslexia and ADHD groups were impaired in processing speed. Also, in the ADHD group, there were signs suggestive of a sustained attention deficit. In dyslexia group, on the other hand, there were no difficulties in sustaining attention. Both clinical groups were unimpaired in divided attention. The only clear difference between dysleksia and ADHD groups was on group level in verbal processing speed. Thus, the results of this study are in agreement with a view that there are similar cognitive problems in dyslexia and ADHD. Also, it is difficult to differentiate these disorders with the dual-task, so the task has the same limitations as many other neuropsychological tasks.