Gait and risk of falls associated with frontal cognitive functions at different stages of Alzheimer's disease

ABSTRACT

The decline in frontal cognitive functions contributes to alterations of gait and increases the risk of falls in patients with dementia, a category which included Alzheimer's disease (AD). The objective of the present study was to compare the gait parameters and the risk of falls among patients at different stages of AD, and to relate these variables with cognitive functions. This is a cross-sectional study with 23 patients with mild and moderate AD. The Clinical Dementia Rating was used to classify the dementia severity. The kinematic parameters of gait (cadence, stride length, and stride speed) were analyzed under two conditions: (a) single task (free gait) and (b) dual task (walking and counting down). The risk of falls was evaluated using the Timed Up-and-Go test. The frontal cognitive functions were evaluated using the Frontal Assessment Battery (FAB), the Clock Drawing Test (CDT) and the Symbol Search Subtest. The patients who were at the moderate stage suffered reduced performance in their stride length and stride speed in the single task and had made more counting errors in the dual task and still had a higher fall risk. Both the mild and the moderate patients exhibited significant decreases in stride length, stride speed and cadence in the dual task. Was detected a significant correlation between CDT, FAB, and stride speed in the dual task condition. We also found a significant correlation between subtest Similarities, FAB and cadence in the dual task condition. The dual task produced changes in the kinematic parameters of gait for the mild and moderate AD patients and the gait alterations are related to frontal cognitive functions, particularly executive functions.     

Development of a new fear of hypoglycemia scale: FH-15

Hypoglycemia is the most common adverse event associated with insulin treatment in diabetes. The consequences of hypoglycemia can be quite aversive and potentially life threatening. The physical sequelae provide ample reason for patients to fear hypoglycemia and avoid episodes. For these reasons, our purpose in this study was to develop a new measure that explores specific fear of hypoglycemia (FH) in adult patients with type 1 diabetes and to examine its psychometric properties. The instrument developed to assess FH was initially made up of 20 items, of which 18 were negative and 2 were positive, assessed on a 5-point Likert scale (1-5). This scale was completed by 229 patients with type 1 diabetes. Additionally, a structured interview and a closed question called subjective fear of hypoglycemia were included as diagnostic criteria. A factor analysis employing the principal-components method and promax rotation was carried out, resulting in a new scale composed of 15 items. Three factors (fear, avoidance, and interference) were obtained and explained 58.27% of the variance. The scale showed good internal consistency (Cronbach's α = .891) and test-retest reliability (r = .908, p < .001), as well as adequate concurrent and predictive validity. The cutoff score that provided the highest overall sensitivity and specificity was set at 28 points. The Fear of Hypoglycemia 15-item scale (FH-15) demonstrated good reliability and validity. This study suggests that the new instrument may serve as a valuable measure of specific FH for use in research and clinical practice.     

Measuring gratitude in youth: assessing the psychometric properties of adult gratitude scales in children and adolescents

Before the developmental trajectory, outcomes, and related interventions of gratitude can be accurately and confidently studied among the youth, researchers must ensure that they have psychometrically sound measures of gratitude that are suitable for this population. Thus, considering that no known scales were specifically designed to measure gratitude in youth, this study aimed to answer an important question: Are the existing gratitude scales used with adults valid for use with youth? The present study is an empirical investigation, based on a large youth sample (N = 1,405) with ages ranging from 10 to 19 years old, of the psychometric properties of scores of the Gratitude Questionnaire-6 (GQ-6; M. E. McCullough, R. A. Emmons, & J.-A. Tsang, 2002), the Gratitude Adjective Checklist (GAC; M. E. McCullough, R. A. Emmons, & J.-A. Tsang, 2002), and the Gratitude Resentment and Appreciation Test (GRAT)-short form (M. Thomas & P. Watkins, 2003). Single-group and multiple-group confirmatory factor analyses indicated that the factor structures of these gratitude scales resemble those found with adults and were invariant across age groups. Scores of all three gratitude scales revealed acceptable internal consistency estimates (i.e., >.70) across age groups. Results showed that whereas scores of all three gratitude scales were positively correlated with each other for 14- to 19-year-olds, GRAT-short form scores tended to display relatively low correlations with scores of the other two measures for younger children (10-13 years old). Furthermore, the nomological network analysis showed that scores of all three gratitude scales were positively correlated with positive affect and life satisfaction scores across the age groups. The relationships with negative affect and depression scores, however, seemed dependent on the child's age. Pending results from subsequent research recommendations for researchers interested in studying gratitude in youth are offered.     

A grammar of action generates predictions in skilled musicians

The present study investigates shared representations of syntactic knowledge in music and action. We examined whether expectancy violations in musical harmonic sequences are also perceived as violations of the movement sequences necessary to produce them. Pianists imitated silent videos showing one hand playing chord sequences on a muted keyboard. Results indicate that, despite the absence of auditory feedback, imitation of a chord is fastest when it is congruent with the preceding harmonic context. This suggests that the harmonic rules implied by observed actions induce expectations that influence action execution. As evidence that these predictions are derived at a high representational level, imitation was more accurate for harmonically incongruent chords than for congruent chords executed with unconventional fingering. The magnitude of the effects of context and goal prioritization increased with musical training. Thus, musical training may lead to a domain-general representation of musical grammar, i.e., to a grammar of action.     

Conditional Discriminations by Preverbal Children in an Identity Matching-to-Sample Task

This study sought to develop methodology for assessing whether children aged 16-21 months could learn to match stimuli on the basis of physical identity in conditional discrimination procedures of the type routinely used in stimulus equivalence research with older participants. The study was conducted in a private room at a daycare center for children and toddlers. The child and the research sat together on the floor facing an apparatus with two windows. Stimuli to be discriminated were toys especially designed to attract the child's attention and maintain continued interest. On simple discrimination and discrimination reversal trials that were programmed in initial training, S+ and S- toys were displayed within the two windows. When the child touched the window containing the toy defined as S+ on a given trial, s/he was allowed to manipulate/play with that toy. Selections of the S- toy ended the trial without a play opportunity. On subsequent identity matching-to-sample trials, the child was first allowed to manipulate a sample toy. Then, S+ (matching) and S- (nonmatching) comparison toys were displayed within the windows, and the selection consequences were the same as on simple discrimination trials. The study provides evidence that preverbal children can master simple and conditional discrimination performances via such procedures, perhaps setting the stage for subsequent studies aimed at establishing procedural control of the discrimination baselines needed to assess the stimulus equivalence potential of children in this age range.     

Cognitive and behavioral functioning in Coffin-Siris syndrome and epilepsy: a case presentation

The authors characterized the cognitive, adaptive, and behavioral sequelae of Coffin-Siris (CS) syndrome and epilepsy in a 7.5-year-old child. Little is known about the early neurobehavioral presentation of CS. Clinical features consistent with this genetic anomaly include underdeveloped tips and nails of the fifth fingers, extended infranasal depression, and craniofacial abnormalities. MRI findings often reveal callosal agenesis. The authors conducted a neuropsychological evaluation and obtained parental ratings of behavioral and adaptive functioning. Attentional abilities were limited. As assessed by the Mullen Scales of Early Learning, receptive language abilities (age equivalent [AE]: 3-3) were relatively stronger than expressive skills (AE: 1-4). Adaptive functioning was low across all domains (Vineland Adaptive Behavior Composite AE: 1-9). On the Behavior Assessment for Children (BASC-2), social skills dysfunction, stereotyped and self-stimulatory behaviors, restricted interests, ritualistic play, and inappropriate object usage were noted. No significant mood disturbances were endorsed. Study findings indicate a diffuse pattern of neurobehavioral deficits in a child with CS and epilepsy. Further clinical assessment and research should include multidimensional assessment techniques, including evaluation of adaptive behavior, in an effort to capture the full range developmental sequelae in children with CS.     

Reorganization of functional and effective connectivity during real-time fMRI-BCI modulation of prosody processing

Mechanisms of cortical reorganization underlying the enhancement of speech processing have been poorly investigated. In the present study, we addressed changes in functional and effective connectivity induced in subjects who learned to deliberately increase activation in the right inferior frontal gyrus (rIFG), and improved their ability to identify emotional intonations by using a real-time fMRI Brain-Computer Interface. At the beginning of their training process, we observed a massive connectivity of the rIFG to a widespread network of frontal and temporal areas, which decreased and lateralized to the right hemisphere with practice. Volitional control of activation strengthened connectivity of this brain region to the right prefrontal cortex, whereas training increased its connectivity to bilateral precentral gyri. These findings suggest that changes of connectivity in a functionally specific manner play an important role in the enhancement of speech processing. Also, these findings support previous accounts suggesting that motor circuits play a role in the comprehension of speech.     

Belief Change in Branching Time: AGM-consistency and Iterated Revision

We study belief change in the branching-time structures introduced in Bonanno (Artif Intell 171:144–160, 2007). First, we identify a property of branching-time frames that is equivalent (when the set of states is finite) to AGM-consistency, which is defined as follows. A frame is AGM-consistent if the partial belief revision function associated with an arbitrary state-instant pair and an arbitrary model based on that frame can be extended to a full belief revision function that satisfies the AGM postulates. Second, we provide a set of modal axioms that characterize the class of AGM-consistent frames within the modal logic introduced in Bonanno (Artif Intell 171:144–160, 2007). Third, we introduce a generalization of AGM belief revision functions that allows a clear statement of principles of iterated belief revision and discuss iterated revision both semantically and syntactically.     

Man-Machine interaction in natural language: Computational models of dialogue

This article presents a state-of-the-art review of studies on computational modeling of dialogue. Particular attention is given to the treatment of ill-formed input, the prevention of the hearer’s misconceptions, the inference of the speaker’s plans, the generation of language, and the recognition of dialogue focus—particularly in terms of implications for linguistics. Specifications and initial results of some recent studies carried out by the author are provided. This article is a revised version of a lecture held at the Third Scientific Meeting “Computer Processing of Linguistic Data,” Bled, 1985.