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Background The impairment of cognitive processes in dyslexia is well established, and according to recent studies, this deficit extends to many aspects of cognitive processes. However, these studies have not focused on Planning, Attention, Simultaneous, and Successive processes. Further research is needed concerning cognitive impairment in dyslexia, especially with Arabic-speaking population. Results Children with reading disability scored significantly lower in the total and all subscales of Cognitive Assessment System (CAS), Planning, Attention, Simultaneous, and Successive (P = 0.000). The children with reading disability obtained worse scores compared with the controls in almost all the subtests of CAS. Conclusion The present study highlighted that children with reading disability have difficulties in cognitive processes across the three age groups compared to normal children, which may help in the development of treatment plans and programs for this problem.

The present study was designed to examine whether a relationship exists between scores on simultaneous and sequential cognitive processes, on one hand, and performance on the Reading Decoding and Arithmetic subtests of the Kaufman Assessment Battery for Children (K–ABC), on the other hand, using a sample of 170 Egyptian school children in Grades 1, 3, and 5. To examine the differential magnitudes of the relationship between scores for cognitive processing and school achievement a two by two (simultaneous × sequential) analysis of variance was calculated with reading decoding and arithmetic scores as dependent variables. The results indicated that cognitive processing, especially simultaneous synthesis, is related to arithmetic as well as decoding during reading. Scores on sequential processing were not significantly related to scores for decoding reading and may not be important as simultaneous processing for mathematical skills. The findings were interpreted in the context of the Arabic orthographic system and in view of the nature of the cognitive and mathematical tasks employed in this study.

The impact of duration of education, cannabis addiction and smoking on cognition and brain aging is studied in 211 normal Egyptian volunteers with mean age 46.4±3.6 years (range: 20–76 years). Subjects were classified into two groups: Gr I (non-addicts) with 174 subjects, mean age 49.9±3.8 years (range 20–76 years), smokers and non-smokers, educated and non-educated and Gr II (cannabis addicts) with 37 subjects, mean age 43.6±2.6 years (range 20–72 years) all smokers, educated and non-educated. Outcome measures included the Paced Auditory Serial Addition test (PASAT) for testing attention and the Trailmaking test A, and B (TMa and TMb) for testing psychomotor performance. Age correlated positively with score of Trailmaking test (TMb) in the non-addict group and in the addict group (TMa and TMb). Years of education correlated negatively with scores of Trialmaking test (TMb) in the non-addict group (Gr I) but not the addict group (Gr II). However, in both groups mean scores of the Trailmaking test (TMa) were significantly lower in subjects with a primary level of education than those with higher levels of education. No significant difference was detected between male smokers and nonsmokers of Gr I (non-addicts) regarding any of the neuropsychological tests. Yet, smokers and the non-educated group had poorer attention compared to non-smokers of the same group. Cannabis addicts (Gr II) had significantly poorer attention than non-addict normal volunteers (Gr I). It is concluded that impairment of psychomotor performance is age related whether in normal non-addicts or in cannabis addicts. A decline in attention was detected in cannabis addicts and has been considered a feature of pathological aging. Education in early life as well as the duration of education are neuroprotectors for brain aging more so in the non-addict than addict group. Though cigarette smoking per se has no effect on cognitive abilities in normal aging, it becomes evident that its association with lack of education impairs attention.

Global and specific cognitive functions were assessed in 57 patients with ischemic strokes subjected to clinical neuropsychiatric, psychometric, electrophysiological and cranial tomographic evaluation. Patients did significantly worse than normal controls in the Blessed dementia scale, Sandoz clinical assessment geriatric scale but not the Folstein mini-mental state examination. Of the specific cognitive functions, attention and psychomotor performance were significantly impaired in stroke patients when compared to normal controls. The impairment in global cognitive functions, attention and psychomotor performance was more evident in chronic than acute cases. Increasing age correlated positively to the deterioration in psychomotor performance and perception. Cranial tomographic size of infarction was significantly related to global cognitive as well as intentional (sensory) memory impairment. The more marked the conventional electroencephalographic abnormalities, the more impaired were the global cognitive functions. High limit of the theta percent power correlated positively to deterioration in psychomotor performance. All P300 parameters except amplitude correlated significantly with impairment of global cognitive function and psychomotor performance in stroke patients.

Eighty-eight normal Egyptian volunteers above the age of 40 years were studied for brain aging and subjected to neuropsychological (the Paced Auditory Serial Addition Test; the Trailmaking test A, B; the Digit Symbol Substitution Test; sensory and secondary memory tests), electrophysiological (computerized EEG, P300 and reaction time measures), and Computerized Cranial Tomography (CCT) assessment. A significant correlation was found between age and both perception (Digit Symbol Substitution Test (DDST) and psychomotor performance (Trailmaking B test (TMb)), reaction time (RT) and the size of the third ventricle. Whereas females were worse in attention (Paced Auditory Serial Addition Test (PASAT)), males had worse performance in secondary memory test. Elderly subjects with vascular risk factors did worse in psychomotor performance (TMa) than subjects with no risk factors. Non-educated subjects showed worse perception (DSST) than educated subjects. A significant decrease in upper and lower limit percent power of the alpha band was found in subjects above 60 years, males, and non-educated subjects. A significant increase in theta activity was found only in non-educated subjects. It is concluded that decline in specific cognitive functions occurs with advancing age. Vascular risk factors and lack of education early in life enhance these changes. Moreover, the EEG slowing in the elderly was linked to lack of education early in life.