Overview

Poly-unsaturated fatty acids (PUFAs) represent a component of lipids that covers a relevant role in human diet and biological functions such as provision of energy, functionality of cell membranes and tissue metabolism. Fatty acids carbon chains can be saturated (with no presence of double bonds) or unsaturated (with one or more double bonds). PUFAs fall into the unsaturated group, and they can be divided into two classes: omega-3 (n-3) and omega-6 (n-6) fatty acids (FAs). PUFAs are relevant components of cellular membranes, phospholipids, and precursors of eicosanoids, which influence neuronal development and functioning, docosahexaenoic acid (DHA) and arachidonic acid (AA) in fact are involved in cell growth, neural signaling, and gene expression. The main natural dietary source for Eicosapentaenoic acid (EPA) and DHA is fish oil. It has also been shown how the Magnocellular system, which includes the retinal ganglion cells, the lateral geniculate nucleus (for the visual system, while the medial geniculate nucleus would be involved for the auditory system) of the thalamus, the posterior parietal cortex, various areas visual of the cortex and part of the cerebellum, is sensitive to the contribution of fatty acids through nutrition. A deficit related to the Magnocellular system, specialized in the processing of stimuli with high temporal frequencies and low spatial frequencies, in both the visual and auditory modalities, has been proposed as one of the causes of Developmental Dyslexia (DD). According to this hypothesis, an alteration at the magnocellular level would affect reading by hampering temporal processing of the visual signal and would reduce the quality of the phonological representations due to imperfect acoustic analysis of the incoming phonemes. It is therefore possible to hypothesize that supplementation of PUFA in dyslexic children would improve the functions of the M-system and thus create better conditions to the remediation of reading difficulties, especially through remediation programs specifically tapping visual attention and rapid processing of visual stimuli. The remediation program currently used at Scientific Institute (IRCCS) Medea, "Tachidino", based on tachistoscopic, hemisphere-specific stimulation and on training of selective visual-spatial attention, has exactly these characteristics.

Hence, the present study aims to test the efficacy of PUFA supplementation before and during treatment with Tachidino.

Eligibility

Inclusion Criteria for DD participants will be:

• A formal diagnosis of Developmental Dyslexia, Specific Reading Disorders or Mixed Learning Disorders
• Age between 7 and 15
• Attending at least the third class of primary school
• Monolingual speakers or bilingual speakers with perfect mastery of the Italian language (equivalent to monolinguals)
• Intelligence Quotient (IQ) >= 80
• At least one z-score below -2 Standard Deviations from age mean in at least one of the following tests: text reading, word reading, nonword reading (Dyslexia and Dysorthography (DDE-2) battery, Memory Training (MT) tests)
• Not having received any specific rehabilitation treatment for dyslexia before

Inclusion criteria for control participants will be:

• Age between 7 and 15
• Attending at least the third class of primary school
• Monolingual speakers or bilingual speakers with perfect mastery of the Italian language (equivalent to monolinguals)
• no reported record of difficulties with reading nor specific learning disorders
• Intelligence Quotient (IQ) >= 80
• No z-score below -1,5 Standard Deviations from age mean in any of the following tests: text reading, word reading, nonword reading ("DDE-2" battery, "MT" tests)

Exclusion Criteria:

• Intellectual disability
• Attention Deficit with Hyperactivity (ADHD)
• Neurological disorders
• Sensory deficits that are not /cannot be corrected-to-normal by lenses or hearing aids.
• Allergy to fish and shellfish
• Absorption Disorders (malabsorption)
• Children already (or recently) on a diet with PUFA supplementation
• Children on a therapy with psychoactive medications (anti-depressant, anxiety-control etc.) or with supplements who have not reached a stable administration schedule.