Predictive accuracy of the wide range assessment of memory and learning in children with attention deficit hyperactivity disorder and reading difficulties

Analyzing Digit Span Components for Assessment of Attention Processes

The Digit Span (DS) subtest of the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) is thought to be a measure of attention, concentration, sequencing, number facility, and auditory short-term memory. An optional WISC-III subtest and part of the Freedom from Distractibility (FD) factor, DS assesses several cognitive constructs, yet its utility in differential diagnosis has been questioned because poor DS or FD performance has been inconsistently associated with attention processes. In this study of 195 children referred for comprehensive neuropsychological evaluations, Digits Forward (DF) and Digits Backward (DB) component scores were found to be differentially predictive of attention, executive function, and behavior rating measures. Results suggest that DB is associated with attention and executive function processes, not the short-term rote auditory memory processes tapped by DF.

There are multiple contributors to the verbal short-term memory deficit in children with developmental reading disabilities

Prior research has put forth at least four possible contributors to the verbal short-term memory (VSTM) deficit in children with developmental reading disabilities (RD): poor phonological awareness that affects phonological coding into VSTM, a less effective phonological store, slow articulation rate, and fewer/poorer quality long-term memory (LTM) representations. This project is among the first to test the four suppositions in one study. Participants included 18 children with RD and 18 controls. VSTM was assessed using Baddeley's model of the phonological loop. Findings suggest all four suppositions are correct, depending upon the type of material utilized. Children with RD performed comparably to controls in VSTM for common words but worse for less frequent words and nonwords. Furthermore, only articulation rate predicted VSTM for common words, whereas Verbal IQ and articulation rate predicted VSTM for less frequent words, and phonological awareness and articulation rate predicted VSTM for nonwords. Overall, findings suggest that the mechanism(s) used to code and store items by their meaning is intact in RD, and the deficit in VSTM for less frequent words may be a result of fewer/poorer quality LTM representations for these words. In contrast, phonological awareness and the phonological store are impaired, affecting VSTM for items that are coded phonetically. Slow articulation rate likely affects VSTM for most material when present. When assessing reading performance, VSTM predicted decoding skill but not word identification after controlling Verbal IQ and phonological awareness. Thus, VSTM likely contributes to reading ability when words are novel and must be decoded.

Sensitivity of the test of memory and learning to attention and memory deficits in children with ADHD

Children with attention deficit hyperactivity disorder (ADHD) exhibit a number of cognitive deficits. The current study compared patterns of attention, learning, and memory impairment on the Test of Memory and Learning (TOMAL) between 80 children with ADHD and 80 normal comparisons who were matched for age and gender. Results demonstrated that children with ADHD performed significantly worse than matched controls on the Attention/Concentration Index and the Sequential Recall Index. ROC analysis indicated that these two indexes had good classification accuracy with AUCs of.76 and.77 respectively. There were also group differences on the other index scores except the Associative Recall Index. Factor analysis of the ADHD sample extracted five factors, including an Attention factor that significantly correlated with performance on nonverbal memory tasks. Significant correlations between the TOMAL Index scores and tests of intelligence and visuomotor integration supported the convergent and discriminant validity of the test. These results provide support for the criterion validity of the TOMAL in assessing neurocognitive deficits in children with ADHD.

Anemia of inflammation is related to cognitive impairment among children in Leyte, the Philippines

Background

Many studies have addressed the relationship between iron deficiency anemia (IDA) and cognitive impairment, but none have evaluated the role of non-iron deficiency anemia (NIDA). One of the main causes of NIDA in developing countries is AI, largely due to infectious diseases, whereby iron is shunted away from bio-available forms to storage forms, making it less accessible for use by host tissues. The objective of this study was to determine the effect of NIDA, due largely to AI in this context, on cognitive function after adjustment for potential confounders.

Methodology

This cross-sectional study was conducted in Leyte, The Philippines among 322 children ages 7–18 years. Blood samples were collected and analyzed at the time of cognition testing. Three stool samples were collected and evaluated by the Kato Katz method for quantitative assessment for Schistosoma japonicum and geo-helminth infection. Socio-economic status (SES) was evaluated by survey. Linear regression models were used to quantify the adjusted relationship between performance in different cognitive domains and both IDA and NIDA.

Principal Findings

After adjusting for age, sex, SES and nutritional status, children in the NIDA had lower scores on the PNIT (P = <0.05) and the WRAML memory domain (P<0.05) compared to children in the non-anemic group. Children in the IDA had lower performance on the PNIT compared to the non-anemic group after controlling for potential confounders (P<0.05).

Conclusions

NIDA, predominantly due to AI in this context, was related to lower performance on two tests of cognitive function. This is likely due to decreased delivery of iron to host tissues in this context, including the CNS.

Past studies have demonstrated that iron deficiency anemia is related to deficits in cognitive fucntioning in children, and treating iron deficiency anemia with iron supplementation can improve cognition. Anemia of inflammation is another type of anemia caused by many diseases of lesser-developed countries including bacterial and parasitic infections. Anemia of inflammation is characterized by disordered iron metabolism, such that iron is sequestered in storage forms, preventing its use from tissues that require it. We hypothesized that decreased iron delivery to the brain in the context of anemia of inflammation might lead to decreased cognitive performance. This study found that children with anemia of inflammation had decreased cognitive performance in specific domains, compared to subjects with no anemia. True total body iron deficiency anemia was related to lower performance in the same domains. The only treatment option for anemia of inflammation is treatment of the underlying disease. Iron supplementation will not prevent cognitive deficits in children with anemia of inflammation. Interventions aimed towards maximizing the cognitive development of children in lesser-developed countries will need to focus on the prevention and treatment of bacterial and parasitic infections.

Memory functioning in children with reading disabilities and/or attention deficit/hyperactivity disorder: a clinical investigation of their working memory and long-term memory functioning

We examined memory functioning in children with reading disabilities (RD), Attention deficit/hyperactivity disorder (ADHD), and RD/ADHD using a clinic sample with a clinical instrument: the Children's Memory Scale, enhancing its generalizability. Participants included 23 children with RD, 30 with ADHD, 30 with RD/ADHD, and 30 controls. Children with RD presented with reduced verbal short-term memory (STM) but intact visual STM, central executive (CE), and long-term memory (LTM) functioning. Their deficit in STM appeared specific to tasks requiring phonetic coding of material. Children with ADHD displayed intact CE and LTM functioning but reduced visual-spatial STM, especially when off stimulant medication. Children with RD/ADHD had deficits consistent with both disorders.

Impact of emotional salience on episodic memory in attention-deficit/hyperactivity disorder: a functional magnetic resonance imaging study

BACKGROUND

Patients with attention-deficit/hyperactivity disorder (ADHD) show episodic memory deficits especially in complex memory tasks. We investigated the neural correlates of memory formation in ADHD and their modulation by stimulus salience.

METHODS

We recorded event-related functional magnetic resonance imaging during an episodic memory paradigm with neutral and emotional pictures in 12 male ADHD subjects and 12 healthy adolescents.

RESULTS

Emotional salience did significantly augment memory performance in ADHD patients. Successful encoding of neutral pictures was associated with activation of the anterior cingulate cortex (ACC) in healthy adolescents but with activation of the superior parietal lobe (SPL) and precuneus in ADHD patients. Successful encoding of emotional pictures was associated with prefrontal and inferior temporal cortex activation in both groups. Healthy adolescents, moreover, showed deactivation in the inferior parietal lobe.

CONCLUSIONS

From a pathophysiological point of view, the most striking functional differences between healthy adolescents and ADHD patients were in the ACC and SPL. We suggest that increased SPL activation in ADHD reflected attentional compensation for low ACC activation during the encoding of neutral pictures. The higher salience of emotional stimuli, in contrast, regulated the interplay between ACC and SPL in conjunction with improving memory to the level of healthy adolescents.

Cognitive functioning in children with and without Attention-deficit/Hyperactivity Disorder with and without comorbid learning disabilities

This study attempted to determine whether children with the combined subtype of attention-deficit/hyperactivity disorder (ADHD) have impairments in cognitive functioning and motor skills. The specific effect of the comorbidity of learning disabilities (LD) was also investigated. A battery of cognitive tests was administered to 26 children with a clinical diagnosis of ADHD-combined subtype (ADHD/C), to 24 children with ADHD/C with a comorbid diagnosis of LD (ADHD/C+LD), and to 102 participants without disabilities, all between ages 7 and 10. The testing battery consisted of tasks assessing memory, visuospatial and verbal abilities, and fine motor skills. In general, the test results of children with ADHD/C were poorer than those of the control group but better than the results of children with a combined ADHD/C+LD diagnosis (with the exception of motor skills). The predictive accuracy of the testing battery tasks in children with ADHD/C and ADHD/C+LD was examined. The results of a standard procedure of discriminant function analyses revealed that the measures correctly classified 73.6% of the children.

The profile of memory function in children with autism

A clinical memory test was administered to 38 high-functioning children with autism and 38 individually matched normal controls, 8-16 years of age. The resulting profile of memory abilities in the children with autism was characterized by relatively poor memory for complex visual and verbal information and spatial working memory with relatively intact associative learning ability, verbal working memory, and recognition memory. A stepwise discriminant function analysis of the subtests found that the Finger Windows subtest, a measure of spatial working memory, discriminated most accurately between the autism and normal control groups. A principal components analysis indicated that the factor structure of the subtests differed substantially between the children with autism and controls, suggesting differing organizations of memory ability.