Neurocognitive correlates of white matter quality in adolescent substance users

Background

Progressive myelination during adolescence implicates an increased vulnerability to neurotoxic substances and enduring neurocognitive consequences. This study examined the cognitive manifestations of altered white matter microstructure in chronic marijuana and alcohol-using (MJ + ALC) adolescents.

Methods

Thirty-six MJ + ALC adolescents (ages 16–19) and 36 demographically similar controls were evaluated with diffusion tensor imaging (Bava et al., 2009) and neurocognitive tests. Regions of group difference in fractional anisotropy (FA) and mean diffusivity (MD) were analyzed in relation to cognitive performance.

Results

In users, lower FA in temporal areas related to poorer performance on attention, working memory, and speeded processing tasks. Among regions where users had higher FA than controls, occipital FA was positively associated with working memory and complex visuomotor sequencing, whereas FA in anterior regions was negatively associated with verbal memory performance.

Conclusions

Findings suggest differential influences of white matter development on cognition in MJ + ALC using adolescents than in non-using peers. Neuroadaptation may reflect additive and subtractive responses to substance use that are complicated by competing maturational processes.     

Changes in illness-related cognitions rather than distress mediate improvements in irritable bowel syndrome (IBS) symptoms and disability following a brief cognitive behavioural therapy intervention

Objective

A previous randomised controlled trial demonstrated that a cognitive behavioural therapy (CBT) self-management intervention significantly improved irritable bowel syndrome (IBS) symptoms and disability compared to treatment as usual (TAU). The current study analysed additional data to establish whether; 1) cognitive, behavioural and emotional factors hypothesized to perpetuate IBS symptoms and disability changed following CBT and, 2) ascertain if changes in these factors over the intervention period mediated treatment effects 6-months later.

Method

IBS patients (CBT = 31, TAU = 33) completed measures pre-and-post intervention including: Brief Illness Perception Questionnaire, Hospital Anxiety & Depression Scale and Cognitive and Behavioural Responses to Symptoms Questionnaire. Path models were evaluated to determine whether changes in cognitive and behavioural factors over the treatment period mediated treatment effects.

Results

Compared to TAU, CBT patients showed significant positive changes on several cognitive variables but not anxiety and depression following intervention. Positive change in illness perceptions following intervention mediated the treatment effect on improved IBS symptom severity and social adjustment six months later. Changes in damaging beliefs mediated the effect on social adjustment.

Conclusions

Change in cognition rather than mood mediated treatment related improvements. Changing negative perceptions of IBS appears to be a particularly important treatment mechanism.     

Recollection training and transfer effects in Alzheimer's disease: effectiveness of the repetition-lag procedure

Objective

This study was designed to extend the use of a memory training technique, known as the repetition-lag procedure, to Alzheimer patients. The specificity of this procedure is to target the process of recollection for improvement.

Method

A group of 12 patients were trained individually for 6 h. The training procedure consisted of a series of yes/no recognition tasks in which some words were repeated throughout the test list across gradually increasing delays. Their performance was evaluated on pre-and-post tests and compared with a recognition practice group and a no contact control group.

Results

Initially, recollection training patients only performed accurately when the delay between repetitions consisted of one intervening word, but by the end of training their performance increased up to four-word intervals. Interestingly, these benefits generalized to other measures of memory, such as working memory, visual memory and source recognition.

Conclusions

Effectiveness of the repetition-lag procedure in Alzheimer’s disease is discussed.     

Functional and connectivity changes during working memory in Huntington’s disease: 18 month longitudinal data from the IMAGE-HD study

Background

This study aimed to characterize, for the first time, 18 month longitudinal changes in both functional activation and functional connectivity during working memory in premanifest Huntington’s disease (pre-HD) and symptomatic HD (symp-HD).

Methods

Functional magnetic resonance imaging (fMRI) was used to investigate longitudinal changes in neuronal activity during working memory performance via an N-BACK task (0-BACK and 1-BACK) in 27 pre-HD, 17 symp-HD, and 23 control participants. Whole-brain analysis of activation and region-of-interest analysis of functional connectivity was applied to longitudinal fMRI data collected at baseline and 18 months follow-up.

Results

Compared with controls, the pre-HD group showed significantly increased activation longitudinally during 1-BACK versus 0-BACK in the lateral and medial prefrontal, anterior cingulate, primary motor, and temporal areas cortically, and caudate and putamen subcortically. Pre-HD far from onset, compared with controls, showed further longitudinal increases in the right and left dorsolateral prefrontal cortex (DLPFC). Longitudinal increased activation in anterior cingulate and medial primary motor areas were associated with disease burden in the pre-HD group. Moreover, in pre-HD increased activation over time in primary motor and putamen regions were associated with average response time during 1-BACK performance. During 1-BACK, functional connectivity between the right DLPFC and posterior parietal, anterior cingulate, and caudate was significantly reduced over 18 months only in the pre-HD group.

Conclusions

Longitudinal reductions in connectivity over 18 months may represent an early signature of cortico-cortical and cortico-striatal functional disconnectivity in pre-HD, whereas the concomitant increased cortical and subcortical activation may reflect a compensatory response to the demands for cognitive resources required during task performance. Our findings demonstrate that functional imaging modalities have the potential to serve as sensitive methods for the assessment of cortical and subcortical responses to future treatment measures.     

Cognitive behaviour therapy for common mental disorders in people with Multiple Sclerosis: A bench marking study

Background

Mental health problems such as depression and anxiety are common in Multiple Sclerosis (MS) and are often under treated.

Aims

This paper reports on the clinical effectiveness of a cognitive behaviour therapy service for common mental disorders in people with MS and compares it to previous randomised controlled trials (RCTs) of cognitive behaviour therapy (CBT) in this population.

Methods

49 patients were deemed appropriate for CBT and 29 accepted treatment. Assessments were completed at baseline and end of treatment and included the Hospital Anxiety & Depression Scale. Results in the form of a standardized effect of treatment were compared with five previous RCTs.

Results

The results from this clinical service indicated statistically significant outcomes with reductions in depression and anxiety. The uncontrolled effect size was large but inferior to those found in published RCTs.

Conclusions

Cognitive behaviour therapy is effective for people with MS in routine clinical practice. Possible limits on effectiveness include more liberal patient selection, lack of specificity in rating scales and heterogeneity of target problems. Given the high rates of distress in this population, routine psychological interventions within neurology services are justifiable. Future research should aim to maximise CBT in such settings.     

Emotional reactivity and regulation in preschool-age children who stutter

Purpose.

This study experimentally investigated behavioral correlates of emotional reactivity and emotion regulation and their relation to speech (dis)fluency in preschool-age children who do (CWS) and do not (CWNS) stutter during emotion-eliciting conditions.

Method.

Participants (18 CWS, 14 boys; 18 CWNS, 14 boys) completed two experimental tasks (1) a neutral (“apples and leaves in a transparent box,” ALTB) and (2) a frustrating (“attractive toy in a transparent box,” ATTB) task, both of which were followed by a narrative task. Dependent measures were emotional reactivity (positive affect, negative affect), emotion regulation (self-speech, distraction) exhibited during the ALTB and the ATTB tasks, percentage of stuttered disfluencies (SDs) and percentage of non-stuttered disfluencies (NSDs) produced during the narratives.

Results.

Results indicated that preschool-age CWS exhibited significantly more negative emotion and more self-speech than preschool-age CWNS. For CWS only, emotion regulation behaviors (i.e., distraction, self-speech) during the experimental tasks were predictive of stuttered disfluencies during the subsequent narrative tasks. Furthermore, for CWS there was no relation between emotional processes and non-stuttered disfluencies, but CWNS's negative affect was significantly related to nonstuttered disfluencies.

Conclusions.

In general, present findings support the notion that emotional processes are associated with childhood stuttering. Specifically, findings are consistent with the notion that preschool-age CWS are more emotionally reactive than CWNS and that their self-speech regulatory attempts may be less than effective in modulating their emotions.Educational objectives. The reader will be able to: (a) communicate the relevance of studying the role of emotion in developmental stuttering close to the onset of stuttering and (b) describe the main findings of the present study in relation to previous studies that have used different methodologies to investigate the role of emotion in developmental stuttering of young children who stutter.     

Response speed, contingent negative variation and P300 in Alzheimer’s disease and MCI

Background

Decreased speed of information processing is a hallmark of Alzheimer’s disease (AD) and mild cognitive impairment (MCI). Recent studies suggest that response speed (RS) measures are very sensitive indicators of changes in longitudinal follow-up studies. Insight into the psycho-physiological underpinnings of slowed RS can be provided by measuring the associated event-related potentials (ERP).

Aims

The current study aims to investigate the relation between RS and its psycho-physiological correlates in AD and MCI.

Methods

Fifteen psychoactive drug-naïve AD patients, 20 MCI patients and twenty age-matched, healthy control subjects participated. Response speed was measured during a simple (SRT) and choice reaction time task (CRT). An oddball and contingent negative variation (CNV) paradigm were used to elicit ERP. To evaluate test-retest reliability (TRR), subjects underwent a similar assessment one week after the first.

Results

The SRT and CRT distinguished the patient groups significantly. The P300 amplitude and latency also distinguished the groups and showed a significant correlation with response speed. The CNV amplitude did not reveal a significant difference between groups and also showed a low TRR.The TRR of the SRT, CRT and P300 amplitude and latency in general was moderate to high.The current study suggests that response speed measures on a behavioural and psycho-physiological level deserve attention as a possible marker in the diagnosis and follow-up of AD.     

Aberrant neural mediation of verbal fluency in autism spectrum disorders

Objective

Contrasts of verbal fluency and automatic speech provide an opportunity to evaluate the neural underpinnings of generativity and flexibility in autism spectrum disorders (ASD).

Method

We used functional magnetic resonance imaging (fMRI) to contrast brain activity in high functioning ASD (n = 17, mean verbal IQ = 117) and neurotypical (NT; n = 20, mean verbal IQ = 112) adolescent and young adult males (12–23 years). Participants responded to three word generation conditions: automatic speech (reciting months), category fluency, and letter fluency.

Results

Our paradigm closely mirrored behavioral fluency tasks by requiring overt, free recall word generation while controlling for differences in verbal output between the groups and systematically increasing the task demand. The ASD group showed reduced neural response compared to the NT participants during fluency tasks in multiple regions of left anterior and posterior cortices, and sub-cortical structures. Six of these regions fell in cortico-striatal circuits previously linked to repetitive behaviors (Langen, Durston, Kas, van Engeland, & Staal, 2011), and activity in two of them (putamen and thalamus) was negatively correlated with autism repetitive behavior symptoms in the ASD group. In addition, response in left inferior frontal gyrus was differentially modulated in the ASD, relative to the NT, group as a function of task demand.

Conclusions

These data indicate a specific, atypical brain response in ASD to demanding generativity tasks that may have relevance to repetitive behavior symptoms in ASD as well as to difficulties generating original verbal responses.     

Effects of green tea extract on learning, memory, behavior and acetylcholinesterase activity in young and old male rats

Objective

To study the effects of green tea extract administration on age-related cognition in young and old male Wistar rats.

Methods

Young and old rats were orally administered 0.5% green tea extract for a period of eight weeks and were evaluated by passive avoidance, elevated maze plus paradigm and changes in acetylcholinesterase activity.

Results

Treatment of young and old rats with the extract resulted in no significant difference in performance on the rota rod treadmill test/righting reflex time. Green tea extract significantly improved learning and memory in older rats, with increased retention latency to enter difference in passive avoidance test. In the elevated maze test, green tea treatment resulted in significantly more number of entries in the enclosed arm by the young and old rats. Decline in acetylcholinesterase activity was observed in the cerebrum of green tea treated old rats in comparison to the green tea treated young rats.

Conclusion

Green tea extract administration is effective in enhancing learning and memory in aged rats, and hence, may serve useful in reversing age-related deficits.     

Investigating the effects of ego depletion on physical exercise routines of athletes

Objectives

Persisting at a task can temporarily reduce one’s ability to persist at subsequent tasks. This phenomenon is known as “ego depletion”. Although ego depletion has been linked to many cognitive tasks less is known about its effect on physical tasks. Even less is known about its effect on practiced physical performance associated with athletes. In modern sport science, the question as to whether or not ego depletion can reduce athletes’ persistence at practiced behaviour should be particularly important. Two experimental studies investigated if ego depletion can reduce athletes’ persistence at a routine physical exercise.

Design

In both experiments, a repeated measures design was employed.

Method

Competitive rowers (Experiment 1) and competitive hockey and rugby players (Experiment 2) attempted to complete as many press-ups (Experiment 1) or sit-ups (Experiment 2) as possible over two separate phases. In one phase, the participants attempted the physical exercise after completing an easy cognitive task. In the other phase, they attempted the physical exercise after completing a difficult cognitive task.

Results

Experiment 1 demonstrated that the competitive rowers completed fewer press-ups after completing a difficult cognitive task than they did after completing an easy task. Experiment 2 demonstrated that the competitive hockey and rugby players completed fewer sit-ups after completing a difficult cognitive task than they did after completing an easy cognitive task.

Conclusions

These findings indicate that athletes’ exercise routines are susceptible to ego depletion and that the strength model of self-regulation is applicable to athletic performance.     

A randomized pilot study of anger treatment for Iraq and Afghanistan veterans

Objective

Anger and aggression are serious problems for a significant proportion of veterans who have served in combat. While prior research has suggested that cognitive behavioral treatments may be effective for anger problems, there are few controlled studies of anger treatment in veterans and no studies of anger treatment focusing exclusively on veterans from the Iraq and Afghanistan wars. This randomized pilot study compared an adapted cognitive behavioral intervention (CBI) to a supportive intervention (SI) control condition for the treatment of anger problems in veterans returning from deployment in Iraq or Afghanistan.

Methods

25 veterans with warzone trauma, problems with anger, and one or more additional hyperarousal symptoms were randomized and 23 started treatment (CBI, n = 12; SI, n = 11). Outcome measures were administered at pre- and post- treatment and at 3 months post-treatment.

Results

CBI was associated with significantly more improvement than SI on measures of anger and interpersonal functioning. Gains were maintained at follow-up.

Conclusions

Findings suggest that CBI may be more effective than an active control providing psychoeducation, relaxation, and supportive therapy for treating anger problems in returning veterans. The findings need to be replicated in an adequately powered and more diverse sample.     

Increased sensitivity to proactive and retroactive interference in amnestic mild cognitive impairment: new insights

Background

Increased sensitivity to proactive (PI) and retroactive (RI) interference has been observed in amnestic mild cognitive impairment (aMCI). PI and RI are often explained as being the result of a response competition mechanism. However, patients with aMCI are supposed to suffer mostly from encoding deficits. We hypothesized that in aMCI interference may occur at encoding and not only at the retrieval stage.

Material and methods

We developed an original paradigm enabling PI and RI to be tested with and without response competitors. Eighteen young controls (YC), 16 elderly controls (EC) and 15 aMCI participated in the study.

Results

The YC and EC groups presented interference effects only in conditions that included a direct response competitor. In contrast, aMCI had interference effects in all conditions including the one without response competitor.

Conclusion

Increased sensitivity to interference in aMCI appears to occur at the encoding/consolidation stage and not only at the retrieval stage, as is the case in healthy subjects. This result is discussed in the context of the associative encoding deficits characterizing aMCI.     

Cognitive Mediators of Treatment for Social Anxiety Disorder: Comparing Acceptance and Commitment Therapy and Cognitive-Behavioral Therapy

Objective

To assess the relationship between session-by-session mediators and treatment outcomes in traditional cognitive-behavioral therapy (CBT) and acceptance and commitment therapy (ACT) for social anxiety disorder.

Method

Session-by-session changes in negative cognitions (a theorized mediator of CBT) and experiential avoidance (a theorized mediator of ACT) were assessed in 50 adult outpatients randomized to CBT (n = 25) or ACT (n = 25) for DSM-IV social anxiety disorder.

Results

Multilevel modeling analyses revealed significant nonlinear decreases in the proposed mediators in both treatments, with ACT showing steeper decline than CBT at the beginning of treatment and CBT showing steeper decline than ACT at the end of treatment. Curvature (or the nonlinear effect) of experiential avoidance during treatment significantly mediated posttreatment social anxiety symptoms and anhedonic depression in ACT, but not in CBT, with steeper decline of the Acceptance and Action Questionnaire at the beginning of treatment predicting fewer symptoms in ACT only. Curvature of negative cognitions during both treatments predicted outcome, with steeper decline of negative cognitions at the beginning of treatment predicting lower posttreatment social anxiety and depressive symptoms.

Conclusions

Rate of change in negative cognitions at the beginning of treatment is an important predictor of change across both ACT and CBT, whereas rate of change in experiential avoidance at the beginning of treatment is a mechanism specific to ACT.     

Long-term stability of cognitive behavioral therapy effects for panic disorder with agoraphobia: A two-year follow-up study

Objective

Cognitive-behavioral therapy (CBT) aims to help patients establish new behaviors that will be maintained and adapted to the demands of new situations. The long-term outcomes are therefore crucial in testing the durability of CBT.

Method

A two-year follow-up assessment was undertaken on a subsample of n = 146 PD/AG patients from a multicenter randomized controlled trial. Treatment consisted of two variations of CBT: exposure in situ in the presence of the therapist (T+) or on their own following therapist preparation (T−).

Results

Both variations of CBT had high response rates and, overall, maintained the level of symptomatology observed at post-treatment with high levels of clinical significance. Effect sizes 24 months following treatment were somewhat lower than at the 6-month follow up. Once patients reached responder status, they generally tended to remain responders at subsequent assessments. Differences were observed for patients that obtained additional treatment during the follow-up period. Expert opinion and subjective appraisal of treatment outcome differed. No robust baseline predictors of 2-year outcome were observed.

Conclusion

Most patients maintain clinically meaningful changes two years following treatment across multiple outcome measures. Approximately 1/3 of patients continued to experience meaningful residual problems.     

Self-help for binge eating disorder in primary care: A randomized controlled trial with ethnically and racially diverse obese patients

Objective

The objective was to examine the effectiveness of a self-help treatment as a first line primary care intervention for binge eating disorder (BED) in obese patients. This study compared the effectiveness of a usual care plus self-help version of cognitive behavioral therapy (shCBT) to usual care (UC) only in ethnically/racially diverse obese patients with BED in primary care settings in an urban center.

Method

48 obese patients with BED were randomly assigned to either shCBT (N = 24) or UC (N = 24) for four months. Independent assessments were performed monthly throughout treatment and at post-treatment.

Results

Binge-eating remission rates did not differ significantly between shCBT (25%) and UC (8.3%) at post-treatment. Mixed models of binge eating frequency determined using the Eating Disorder Examination (EDE) revealed significant decreases for both conditions but that shCBT and UC did not differ. Mixed models of binge eating frequency from repeated monthly EDE-questionnaire assessments revealed a significant treatment-by-time interaction indicating that shCBT had significant reductions whereas UC did not during the four-month treatments. Mixed models revealed no differences between groups on associated eating disorder psychopathology or depression. No weight loss was observed in either condition.

Conclusions

Our findings suggest that pure self-help CBT did not show effectiveness relative to usual care for treating BED in obese patients in primary care. Thus, self-help CBT may not have utility as a front-line intervention for BED for obese patients in primary care and future studies should test guided-self-help methods for delivering CBT in primary care generalist settings.     

The efficacy of massage on short and long term outcomes in preterm infants

Purpose

Premature infants lack the tactile stimulation they would have otherwise experienced in the womb. Infant massage is a developmentally supportive intervention that has been documented for several decades to have a positive effect on both full term and preterm infants. The purpose of this study was to assess the short and long term benefits of massage on stable preterm infants.

Methods

A quasi experimental design was used, 66 infants were recruited from two university hospitals with tertiary level NICUs; 32 infants received the massage therapy by their mothers. Data collection by a researcher blind to the infants’ group assignments included weight at discharge, pain responses on the PIPP scale at discharge, length of stay in hospital, neuro-developmental outcome (Bayley scores) and breastfeeding duration at 12 months corrected age.

Results

Infants who were massaged had significantly lower scores on the PIPP after a heel-stick compared to before the massage and had lower PIPP scores at discharge compared to the control group. Massaged infants had higher cognitive scores at 12 months corrected age. Weight gain, length of stay, breastfeeding duration and motor scores did not differ between groups.

Conclusion

Stable preterm infants benefit from massage therapy given by their mothers and may be a culturally acceptable form of intervention to improve the outcomes of preterm infants.     

Treating PTSD in refugees and asylum seekers within the general health care system. A randomized controlled multicenter study

Objective

There has been uncertainty about whether refugees and asylum seekers with PTSD can be treated effectively in standard psychiatric settings in industrialized countries. In this study, Narrative Exposure Therapy (NET) was compared to Treatment As Usual (TAU) in 11 general psychiatric health care units in Norway. The focus was on changes in symptom severity and in the diagnostic status for PTSD and depression.

Method

Refugees and asylum seekers fulfilling the DSM-IV criteria for PTSD (N = 81) were randomized with an a-priori probability of 2:1 to either NET (N = 51) or TAU (N = 30). The patients were assessed with Clinician Administered PTSD Scale, Hamilton rating scale for depression and the MINI Neuropsychiatric Interview before treatment, and again at one and six months after the completion.

Results

Both NET and TAU gave clinically relevant symptom reduction both in PTSD and in depression. NET gave significantly more symptom reduction compared to TAU as well as significantly more reduction in participants with PTSD diagnoses. No difference in treatment efficacy was found between refugees and asylum seekers.

Conclusions

The study indicated that refugees and asylum seekers can be treated successfully for PTSD and depression in the general psychiatric health care system; NET appeared to be a promising treatment for both groups.

ClinicalTrials.gov registry number

NCT00218959.     

Impaired awareness of movement disorders in Parkinson’s disease

Background

This study analyzed the presence of awareness of movement disorders (dyskinesias and hypokinesias) in 25 patients with Parkinson’s disease (PD) and motor fluctuations (dyskinesias, wearing off, on–off fluctuations). Of the few studies that have dealt with this topic, none have analyzed the differences in the awareness of motor deficits by comparing the on and off states using motor scales and an extensive battery of tests to assess cognitive and behavioral functioning.

Methods

PD patients were compared on three different scales that we have devised to measure awareness of movement disorders: Global Awareness of Movement (GAM) Disorders, dyskinesia/hypo-bradykinesia rating scales.

Results

Data showed that PD patients had greater awareness and psychological suffering in the off state than in the on state. In particular, they were troubled by motor disabilities related to hypokinesias and had mood-related symptoms and a perception of disability in activities of daily living. Interestingly, patients only showed a selective reduction of awareness of movement disorders associated with executive functions and related to dyskinesias in the on state, compared to a preserved awareness of hypokinesias in the off state. On the contrary, no association with executive functions was found in the off state.

Conclusion

Our findings suggest that the dopaminergic overstimulation of mesocorticolimbic pathways may cause a dysfunction of prefrontal–subcortical connections related to the impaired insight.     

Are parenting interventions effective in improving the relationship between mothers and their preterm infants?

Aim

To systematically review the efficacy of parenting interventions in improving the quality of the relationship between mothers and preterm infants.

Method

Randomized or quasi-randomized controlled trials (RCT) of parenting interventions for mothers of preterm infants where mother–infant relationship quality outcomes were reported. Databases searched: The Cochrane Library, PubMed, CINAHL, PsycINFO and Web of Science.

Results

Seventeen studies met the inclusion criteria, 14 with strong methodological quality. Eight parenting interventions were found to improve the quality of the mother–preterm infant relationship.

Conclusions

Heterogeneity of the interventions calls for an integrated new parenting program focusing on cue-based, responsive care from the mother to her preterm infant to improve the quality of the relationship for these mother–preterm infant dyads.     

Comparison of tongue muscle characteristics of preterm and full term infants during nutritive and nonnutritive sucking

Background

Independent oral feeding requires coordination of suck, swallow and breathe and the lingual musculature plays a significant role in this coordinative action. However, clinical benchmarks of lingual function fundamental to successful feeding have not been explored.

Aims

The present study tests our model for quantifying infant lingual force and size and compares the muscle measures of interest in two cohorts: healthy full-term infants (FT) (N = 5) and healthy preterm infants (PT) (N = 6).

Method

Using an instrumented pacifier and bottle nipple, we determined the resultant compressive forces applied to the nipple by the tongue during nutritive (NS) and nonnutritive sucking (NNS). Muscle size was estimated from measures of posterior tongue thickness using ultrasonography.

Results

After controlling for weight and post menstrual age, statistically significant differences were found between FT and PT infants beginning to feed for NNS frequency and NS tongue force. Clinically significant differences were detected for NNS tongue force and posterior tongue thickness. Additionally, PT infants demonstrated a significant difference in mean tongue force between NS and NNS and FT infants did not. FT infants demonstrated a significant difference in mean frequency between NS and NNS and PT infants did not. Linear regression indicated that mean posterior tongue thickness alone predicted 55% of the variance in NS force.

Conclusions

Results demonstrate the feasibility of our approach and suggest that infant tongue muscle characteristics necessary for successful feeding differ between healthy full term infants and preterm infants who are beginning oral feeding.