January 1, 2013 Association

From the Journals: January 2013

No Difference Between Computer- and Paper-Based Comprehension

Shifting from paper- to computer-based reading had little to no effect on adolescents' reading comprehension, according to a study in the October 2012 issue of Language, Speech, and Hearing Services in Schools

Researchers asked 14 adolescents with language-learning disabilities and 25 adolescents with typical language development to read literary texts in computer- and paper-based formats and then to answer reading comprehension questions. The students with language-learning disabilities scored significantly lower than students with typically developing language on the reading comprehension measure. But researchers found no significant differences in reading or answering time between groups.

The results were tempered by the study's limitations: a small sample size, not requiring participants to read hyperlinked pages to answer questions correctly, and a lack of information about how students navigated text in both conditions. But given these methodological limitations, reading on a computer screen or sheet of paper did not seem to affect comprehension for either group.

Sound Booth Proves Best for Remote Speech Perception

The listening environment, rather than the software used, has more of an effect on speech perception for people with cochlear implants who receive telehealth audiologic services, according to a study in the October 2012 issue of the Journal of Speech, Language, and Hearing Research. The results suggest that regardless of the remote system used, speech perception is best when evaluated in a sound-treated booth.

Researchers evaluated the effects of remote systems and acoustic environment on speech perception via telehealth for 16 adults and children who use cochlear implants. They measured speech perception in quiet and in noise, using the Polycom visual concert (a system designed to transmit high-resolution graphics and audio remotely) and a hybrid presentation system (custom software designed to eliminate bandwidth and compression issues).

For speech in quiet, the environment played a strong role, with better performance in a sound-treated booth than in a nearby Cochlear Implant Research Laboratory office; the system used had no effect. Speech in noise revealed interactions between environment and system: participants performed more poorly on Polycom visual concert in the office, but performance in a sound-treated booth was no different. The hybrid presentation system was superior for listening to speech-in-noise in a reverberant environment. The authors suggest that future research be geared toward modifications to non-sound-treated environments to improve telehealth service delivery in rural areas.

Earlier CI Implantation Spurs Speech Development

Receiving cochlear implants at a young age has value for children's phonological development, according to a study in the November 2012 American Journal of Speech-Language Pathology. Although their language development was still delayed compared to those in a control group, young cochlear implant recipients showed substantial progress in consonant acquisition.

Eleven young cochlear implant recipients and 11 age- and gender-matched typically developing peers produced target words in short sentences. Researchers examined the children's consonant production accuracy for total scores, initial and final word positions, and three developmental sound classes: early, middle and late.

English-speaking children who received implants before age 3 and participated in oral intervention programs made substantial progress in consonant sound acquisition during their first two years of implant use. According to the overall accuracy rating, they reached a moderate level of competence across a wide variety of consonants. 

But the relatively low scores highlighted in the study suggest that clinicians might need to increase their emphasis on final consonants during speech training with young cochlear implant recipients.

Cardiorespiratory Health May Predict Better Hearing

Physical fitness is a strong predictor of various health outcomes, and improved hearing may soon be added to that list. Researchers have found a correlation between cardiorespiratory fitness and hearing sensitivity, according to a study in the June 2012 American Journal of Audiology, but further research is needed to confirm the findings.

Following up on previous, smaller-scale studies, researchers examined data from the 1999–2004 National Health and Nutrition Examination Survey. Their final sample included 1,082 survey participants ages 20–49 years, a nationally representative sample of U.S. adults. Researchers used an established nonexercise prediction equation, and extrapolation of heart-rates during treadmill tests, to obtain participants' maximum oxygen uptake. They then compared this information with audiometric data showing participants' low and high pure-tone frequency averages.

Maximum oxygen uptake was not associated with hearing when the heart-rate extrapolation method was used. However, with the nonexercise prediction equation, oxygen uptake correlated with greater hearing sensitivity for women. Women with higher predicted cardiorespiratory fitness were six percent more likely than less-fit women to have good hearing as opposed to worse hearing. Although these findings suggest a potentially auditory-protective effect of physical fitness, researchers caution that further confirmatory studies are needed.

Researchers Find Gene That Nearly Triples Risk of Alzheimer's 

An international team including researchers from Mayo Clinic has identified a gene so powerful it nearly triples the risk of Alzheimer's disease. It is the most potent genetic risk factor for Alzheimer's identified in the past 20 years, according to a study in the New England Journal of Medicine (November 2012).

Using new sequencing techniques to home in on the TREM2 gene, researchers then conducted additional TREM2 sequencing. These studies led to identification of a set of rare variants in TREM2 that occurred more often in 1,092 Alzheimer's disease patients than in a control group of 1,107 healthy people. 

Then researchers evaluated the most common variant, R47H, in follow-up studies of a large number of people with Alzheimer's disease and controls. They genotyped and analyzed R47H in DNA samples from 1,994 people with Alzheimer's disease and 4,062 "control" participants—individuals verified not to have Alzheimer's. 

Evaluation of the patients and control participants in follow-up studies showed unequivocally that the R47H variant of TREM2 substantially increases the risk of Alzheimer's disease. Search doi: 10.1056/NEJMoa1211851.

Metal-Binding Agent Ineffective as Autism Treatment

Metal-binding agents rubbed into the skin, prescribed by some alternative practitioners for the treatment of autism, are not absorbed and therefore are unlikely to be effective at helping the body excrete excess mercury, a new study finds. 

The study, published online in Springer's Journal of Medical Toxicology (December 2012), provides evidence against the use of these treatments in children with autism.

In the study, eight healthy adult volunteers and one control subject ingested oral DMPS (2,3-Dimercaptopropane-1-sulfonate), which is proven to increase mercury excretion. DMPS is approved in Europe for the treatment of heavy metal toxicity, but is not approved by the U.S. Food and Drug Administration for use in the United States.

For the first time, researchers looked at whether topically applied DMPS is absorbed into the body by measuring levels in the blood 30, 60, 90, 120, and 240 minutes after application. They also measured whether DMPS applied to the skin leads to increased excretion of mercury in the urine 12 and 24 hours after application. 

None of the urine samples collected from healthy subjects contained detectable DMPS. DMPS also was not detected in 40 of 41 blood samples, with a single sample found to have a small amount of DMPS, considered by the authors to be contamination of the sample. The control subject given oral DMPS had increased levels of DMPS in the blood and also detectable DMPS in the urine. In addition, topical application of DMPS did not lead to increased mercury excretion, whereas oral intake led to a six-fold increase. Search doi: 10.1007/s13181-012-0272-9.

Targeted Genetic Testing Unmasks Unexplained Hearing Loss

Genetic testing for a certain mutation in pediatric patients is valuable in determining a cause for unexplained hearing loss, according to a study in Otolaryngology–Head and Neck Surgery (November 2012). According to the study's authors, targeted testing for some of the most common mutations that cause sensorineural hearing loss yields the best results, rather than generalized screening of hearing loss patients.

University of Miami researchers conducted a nine-year study on 221 adult and 163 pediatric patients with sensorineural hearing loss. They screened blood samples for mutations in GJB2, GJB6 and mitochondrial DNA mutations, conducted audiometric tests, and took patient and family histories.

Researchers identified mutations in the GJB2/GJB6 genes in 23 of 163 pediatric patients, but only 3 of 221 adults. Researchers determined that 13 percent of the pediatric patients carried the mutation. The mitochondrial testing in adults returned a higher rate (three percent) than what is usually reported (one percent). Identifying DFNB1 mutations early will provide carriers with a number of options, including risk factor avoidance and pharmaceutical options to prevent hearing loss from progressing, or to improve existing conditions. Search doi: 10.1177/0194599812453553.

Model Provides Insight Into How Timbre Works

Researchers at Johns Hopkins University have used mathematical models—based on experiments in animals and humans—to accurately predict sound source recognition and perceptual timbre judgments by human listeners. The study is published in PLOS Computational Biology (November 2012).

"Timbre" is a major contributor to humans' ability to analyze music and recognize instruments. Timbre is a hard-to-quantify concept, loosely defined as everything in music that isn't duration, loudness or pitch. For instance, timbre comes into play when a listener can instantly decide whether a sound is coming from a violin or a piano.

The authors devised a computer model to accurately mimic how specific brain regions transform sounds into the nerve impulses that allow listeners to recognize sound types. The model was able to correctly identify which of 13 instruments was playing to an accuracy rate of 98.7 percent.

Then researchers asked 20 people to listen to two sounds played by different musical instruments, and rate how similar the sounds seemed. A violin and a cello are perceived as closer to each other than a violin and a flute. 

The researchers also found that overall, wind and percussive instruments tend to be the most different from each other, followed by strings and percussions, then strings and winds. These subtle judgments of timbre quality were also reproduced by the computer model. Search doi: 10.1371/journal.pcbi.1002759.

Virtual Reality a Better Predictor of Cognitive Impairment?

A virtual reality test being developed at the University of Toronto Scarborough is showing an edge over pencil-and-paper tests at predicting whether a cognitive impairment will have real-world consequences. 

The test, called Multitasking in the City Task, uses a computer-game-like virtual world and asks volunteers to navigate their ways through tasks such as delivering packages or running errands. Researchers tested 13 people who had suffered stroke or traumatic brain injury, giving them a battery of standard tests as well as the virtual reality test. They also gave them a questionnaire to determine how severely their cognitive deficits affected their daily lives. 

The results showed that the standard tests—which require volunteers to solve math problems, sort cards or remember names—didn't predict how big an impact the participants' cognitive deficits had on their daily lives.

For more information visit Applied Neuropsychology Adult.


  

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