Learning disabilities affect also adults and one individual can have multiple disabilities
Learning disability complicates the life, studies, and work of at least 5% of a population. These developmental difficulties do not always resolve before reaching adulthood. Instead, some characteristics may actually be aggravated with increasing adult age. Learning disabilities may also coexist in an individual, frequent examples are specific reading disorder (dyslexia) and hyperkinetic disorders [attention deficit (hyperactivity) disorder, ADHD]. Especially dyslexia research is necessary in Finland, since our shallow orthography may prevent the direct generalization of research conducted in English. Regardless of the large amount of previous research, the clinical neuropsychological characteristics of adult dyslexia occurring alone or together with ADHD in different languages are unknown.
Various cognitive difficulties have been suggested to correlate with learning disabilities
Learning disability research has also focused on experimental studies of basic cognitive capacities that correlate with the disabilities (and possibly cause them). Previous research has found that, in addition to phonological processing, especially temporal processing, short-term memory, and attention are basic cognitive capacities that correlate with dyslexia. However, previous research is confounded by the possible coexistence of the learning disabilities. Defining the basic cognitive capacities of learning disabilities when they appear separately or coexist would clarify the diagnostics and suggest future clinical neuropsychological methods assessing the relevant capacities.
The biological bases of learning disabilities are still unknown
In addition to the increased knowledge of the basic cognitive capacities, the diagnostics of learning disabilities will in future be clarified by the increased knowledge of their biological correlates. Previous research related to reading difficulties has suggested that genotype, fatty acids, magnocellular system, and cerebellum could be biological factor candidates.
Project DyAdd investigates adult dyslexia and ADHD when they coexist or appear separately in a shallow Finnish orthography. The main objectives are:
- To investigate the neurocognitive difficulties of the disabilities with clinical neuropsychological methods and to define a clinical neuropsychological protocol for adult clinical neuropsychology.
- To investigate the basic cognitive capacities of the disabilities with experimental methods, that is, learning and memory, attention, and temporal processing (and magnocellular functions in relation to the last). The aim is to find shared and differentiating capacities and therefore future clinical neuropsychological methods.
- To investigate the relations between neuropsychological, experimental, and biological measures. Biological measures in the project are related to genetics and serum lipid fatty acids. The role of cerebellum is investigated by comparing the learning disability groups to a group with inherited developmental cerebellar atrophy.