The gut microbiome and cognition in Parkinson's disease: a systematic review

BACKGROUND

The pathology underlying cognitive changes in people with Parkinson's disease (PD) is not well understood. In healthy older adults, gut microbiome composition has been associated with cognitive function. In people with PD, preliminary evidence suggests that cortical spreading of abnormal alpha-synuclein aggregates may be associated with cognitive impairment. As changes in the gut have been linked to PD onset and associated Lewy body pathology, an investigation of the gut microbiome and cognition in PD is warranted.

OBJECTIVE

To synthesise existing evidence on the relationship between the gut microbiome and cognitive function in PD.

METHODS

A systematic review was conducted to search for peer-reviewed articles and grey literature published to July 2021 across seven electronic databases (MEDLINE, EMBASE, PsycINFO, Scopus, Cochrane Library, ProQuest, and ProQuest Dissertations and Theses). English language articles reporting the relationship between cognition and the gut microbiome in human participants with PD were considered for inclusion. Results were qualitatively synthesised and evidence quality was assessed using the QualSyst tool for quantitative studies.

RESULTS

Five cross-sectional studies reporting the association between the gut microbiome and cognition in 395 participants with PD were included. Studies provided preliminary evidence of a relationship between cognition and gut microbiota within the Bacteroidetes and Firmicutes phyla, however, associations with specific genera were inconsistent across studies.

CONCLUSIONS

Some species of short-chain fatty acid-producing bacteria (e.g. acetate, butyrate, and propionate producers) appear to be reduced in participants with PD with cognitive impairment. More research with larger samples and more consistent methodology is needed to substantiate these findings.

Experiences of parents of trans young people accessing Australian health services for their child: Findings from Trans Pathways

Background

Many trans young people seek mental health support and gender-affirming medical interventions including puberty suppression, gender-affirming hormones and/or surgeries. Trans young people and their parents face multiple barriers in accessing gender-affirming care and mental health support, however little is known about the parent perspective on accessing services for their trans child.

Aims

This study aimed to understand the experiences of parents accessing medical and mental health services with and for their trans children within Australia.

Methods

Using data from Trans Pathways, a large mixed-methods cross-sectional study, we examined the experiences of parents (N = 194) in Australia accessing primary care, psychiatry, therapy/counseling, mental health inpatient, and gender-affirming medical services with/for their trans children (aged 25 years or younger). Qualitative data on service experiences were thematically analyzed. Quantitative analyses included frequency of access to services, wait times, service satisfaction, and mental health diagnoses of the parents' trans child.

Results

Services were mostly first accessed when the young person was between 12 and 17 years of age, with primary care physicians being the most accessed service. Parents reported that some practitioners were respectful and knowledgeable about gender-affirming care, and others lacked experience in trans health. Across all services, common barriers included long wait times, complicated pathways to navigate to access support, as well as systemic barriers such as sparsity of gender speciality services. Across services, parents reported feeling as though they do not have the necessary tools to best support their child in their gender affirmation.

Discussion

This study highlights the crucial need for systemic changes in the processes of accessing gender-affirming care and mental health support to enable access to appropriate and timely care. These findings also indicate the importance of improving individual practitioner knowledge around trans health, to enhance the support provided to trans young people and their parents.

Motor cortex excitability in chronic low back pain

Chronic pain is associated with dysfunctional cortical excitability. Research has identified altered intracortical motor cortex excitability in Chronic Lower Back Pain (CLBP). However, research identifying the specific intracortical changes underlying CLBP has been met with inconsistent findings. In the present case-control study, we examined intracortical excitability of the primary motor cortex using transcranial magnetic stimulation (TMS) in individuals with CLBP. Twenty participants with CLBP (M_age = 54.45 years, SD_age = 15.89 years) and 18 age- and gender-matched, pain-free controls (M = 53.83, SD = 16.72) were included in this study. TMS was applied to the hand motor area of the right hemisphere and motor evoked potentials (MEPs) were recorded from the first dorsal interosseous muscle of the contralateral hand. Resting motor threshold (rMT) and MEP amplitude were measured using single-pulse stimulation. Short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were assessed using paired-pulse stimulation. Individuals with CLBP had significantly higher rMT (decreased corticospinal excitability) and lower ICF compared to controls. No significant differences were found in MEP amplitude and SICI. These findings add to the growing body of evidence that CLBP is associated with deficits in intracortical modulation involving glutamatergic mechanisms.

Measuring General Expectations of Advanced Stage Treatment Outcomes in Parkinson's Disease

BACKGROUND

Recent research suggests that a significant number of those who receive advanced treatments for Parkinson's disease (PD) do not report improvements for some symptoms, which may relate to their pre-treatment expectations. It is important that expectations of treatment are measured and discussed prior to advanced treatment.

OBJECTIVE

The primary aim of this study was to develop a measure of treatment expectations of two advanced-stage treatments in PD, deep brain stimulation (DBS), and Levodopa/Carbidopa Intestinal Gel (LCIG). A secondary aim was to explore potential predictors of treatment expectations.

METHODS

The questionnaire-based measure was developed by researchers in conjunction with a highly experienced clinician, and evaluated treatment expectations in 189 people aged 46-91 years (M = 71.35, SD = 8.73; 61% male) with idiopathic PD.

RESULTS

The overall measure demonstrated excellent internal consistency (α= 0.96). Exploratory factor analysis suggested the scale was unidimensional for both DBS and LCIG. Participant expectations of the two treatments differed significantly, with expectations being higher for DBS. Perceived symptom severity was the strongest predictor of treatment expectations.

CONCLUSION

This scale has potential to inform clinicians about client expectations prior to advanced stage therapy for PD, with a view to the management of these expectations. Further evaluation of the scale is required across different treatment contexts.

Cognitive profile and mild cognitive impairment in people with chronic lower back pain

A growing body of evidence suggests Chronic Lower Back Pain (CLBP) is associated with cognitive dysfunction. Little is known, however, about the extent of cognitive impairment in CLBP. The present study explored the cognitive profile of people with CLBP and sought to determine the extent of Mild Cognitive Impairment (MCI) according to the DSM-V and the Movement Disorders Society criteria for MCI. Thirty-one participants with CLBP and 27 age and gender matched healthy controls completed a full neuropsychological battery, consisting of two tasks for each of the five cognitive domains (Executive Function, Attention/Working Memory, Memory, Language, and Visuospatial). Participants with CLBP performed worse, compared to controls, on measures of Attention/Working Memory, Memory, Language, and Visuospatial performance. Cognitive performance in CLBP was also compared to equivalent normative data to determine cognitive impairment. Sixteen CLBP participants were impaired on at least one cognitive measure, with 5 participants meeting criteria for MCI. MCI was not associated with pain-related experience, or psychological health. The present study supports and extends previous findings that CLBP is associated with cognitive dysfunction and some people with CLBP meet criteria for MCI. These findings support that rehabilitation in people with CLBP requires a multidisciplinary approach.

Hearing Loss and Depression in Older Adults: A Systematic Review and Meta-analysis

Background and Objectives

Studies reporting an association between hearing loss and depression in older adults are conflicting and warrant a systematic review and meta-analysis of the evidence.

Research Design and Methods

A search of academic databases (e.g., MEDLINE) and gray literature (e.g., OpenGrey) identified relevant articles published up to July 17, 2018. Cross-sectional or cohort designs were included. Outcome effects were computed as odds ratios (ORs) and pooled using random-effects meta-analysis (PROSPERO: CRD42018084494).

Results

A total of 147,148 participants from 35 studies met inclusion criteria. Twenty-four studies were cross-sectional and 11 were cohort designs. Overall, hearing loss was associated with statistically significantly greater odds of depression in older adults (OR = 1.47, 95% confidence interval [CI] = 1.31−1.65). When studies were stratified by design, hearing loss was associated with greater odds of depression in cross-sectional studies (OR = 1.54, 95% CI = 1.31−1.80) and cohort studies (OR = 1.39, 95% CI = 1.16 − 1.67), and there was no difference between cross-sectional or cohort effect estimates (Q = 0.64, p = .42). There was no effect of moderator variables (i.e., hearing aid use) on the association between hearing loss and depression, but these findings must be interpreted with caution. There was no presence of publication bias but certainty in the estimation of the overall effect was classified as “low.”

Discussion and Implications

Older adults may experience increased odds of depression associated with hearing loss, and this association may not be influenced by study or participant characteristics.

Beyond factor analysis: Multidimensionality and the Parkinson's Disease Sleep Scale-Revised

Many studies have sought to describe the relationship between sleep disturbance and cognition in Parkinson’s disease (PD). The Parkinson’s Disease Sleep Scale (PDSS) and its variants (the Parkinson’s disease Sleep Scale-Revised; PDSS-R, and the Parkinson’s Disease Sleep Scale-2; PDSS-2) quantify a range of symptoms impacting sleep in only 15 items. However, data from these scales may be problematic as included items have considerable conceptual breadth, and there may be overlap in the constructs assessed. Multidimensional measurement models, accounting for the tendency for items to measure multiple constructs, may be useful more accurately to model variance than traditional confirmatory factor analysis. In the present study, we tested the hypothesis that a multidimensional model (a bifactor model) is more appropriate than traditional factor analysis for data generated by these types of scales, using data collected using the PDSS-R as an exemplar. 166 participants diagnosed with idiopathic PD participated in this study. Using PDSS-R data, we compared three models: a unidimensional model; a 3-factor model consisting of sub-factors measuring insomnia, motor symptoms and obstructive sleep apnoea (OSA) and REM sleep behaviour disorder (RBD) symptoms; and, a confirmatory bifactor model with both a general factor and the same three sub-factors. Only the confirmatory bifactor model achieved satisfactory model fit, suggesting that PDSS-R data are multidimensional. There were differential associations between factor scores and patient characteristics, suggesting that some PDSS-R items, but not others, are influenced by mood and personality in addition to sleep symptoms. Multidimensional measurement models may also be a helpful tool in the PDSS and the PDSS-2 scales and may improve the sensitivity of these instruments.

Cognitive Training and Noninvasive Brain Stimulation for Cognition in Parkinson's Disease: A Meta-analysis

BACKGROUND

Many people with Parkinson's disease (PD) experience cognitive decline. It is not known whether cognitive training or noninvasive brain stimulation are effective at alleviating cognitive deficits in PD.

OBJECTIVE

To examine cognitive training and non-invasive brain stimulation interventions for cognition in PD.

METHODS

An extensive search was conducted of published and unpublished studies in online databases. Studies were selected if they were controlled trials examining standard (not individualized) or tailored (individualized) cognitive training, repetitive transcranial magnetic stimulation (rTMS), or transcranial direct current stimulation (tDCS) in PD, with outcomes measured by standardized neuropsychological tests.

RESULTS

Fourteen controlled trials met inclusion criteria. For executive function, the pooled effect size (Hedges' g) for cognitive training (standard and tailored combined) was small ( g = 0.42) but statistically significant (95% CI 0.15-0.68). The pooled effect for standard cognitive training (alone) was medium ( g = 0.51) and significant (95% CI 0.16-0.85). For attention/working memory, small pooled effect sizes were found when combining standard and tailored cognitive training ( g = 0.23; 95% CI 0.02-0.44) and for standard cognitive training alone ( g = 0.29; 95% CI 0.04-0.53), both significant. For memory, small but significant pooled effect sizes were also found when combining standard and tailored cognitive training and for standard cognitive training alone.

CONCLUSIONS

The results suggest that standard and tailored cognitive training may improve executive function, attention/working memory, and memory in PD. Future studies must adopt randomized controlled trial designs to explore the therapeutic potential of these interventions.

Prevalence and Subtypes of Mild Cognitive Impairment in Parkinson's Disease

The current study examined the prevalence and subtypes of Mild Cognitive Impairment (MCI) in an Australian sample of people with Parkinson’s Disease (PD). Seventy participants with PD completed neuropsychological assessments of their cognitive performance, using MDS Task Force Level II diagnostic criteria for PD-MCI. A cut-off score of less than one standard deviation (SD) below normative data determined impaired performance on a neuropsychological test. Of 70 participants, 45 (64%) met Level II diagnostic criteria for PD-MCI. Among those with PD-MCI, 42 (93%) were identified as having multiple domain impairment (28 as amnestic multiple domain and 14 as nonamnestic multiple domain). Single domain impairment was less frequent (2 amnestic/1 nonamnestic). Significant differences were found between the PD-MCI and Normal Cognition groups, across all cognitive domains. Multiple domain cognitive impairment was more frequent than single domain impairment in an Australian sample of people with PD. However, PD-MCI is heterogeneous and current prevalence and subtyping statistics may be an artifact of variable application methods of the criteria (e.g., cut off scores and number of tests). Future longitudinal studies refining the criteria will assist with subtyping the progression of PD-MCI, while identifying individuals who may benefit from pharmacological and nonpharmacological interventions.

Psychological Literacy Weakly Differentiates Students by Discipline and Year of Enrolment

Psychological literacy, a construct developed to reflect the types of skills graduates of a psychology degree should possess and be capable of demonstrating, has recently been scrutinized in terms of its measurement adequacy. The recent development of a multi-item measure encompassing the facets of psychological literacy has provided the potential for improved validity in measuring the construct. We investigated the known-groups validity of this multi-item measure of psychological literacy to examine whether psychological literacy could predict (a) students' course of enrolment and (b) students' year of enrolment. Five hundred and fifteen undergraduate psychology students, 87 psychology/human resource management students, and 83 speech pathology students provided data. In the first year cohort, the reflective processes (RPs) factor significantly predicted psychology and psychology/human resource management course enrolment, although no facets significantly differentiated between psychology and speech pathology enrolment. Within the second year cohort, generic graduate attributes (GGAs) and RPs differentiated psychology and speech pathology course enrolment. GGAs differentiated first-year and second-year psychology students, with second-year students more likely to have higher scores on this factor. Due to weak support for known-groups validity, further measurement refinements are recommended to improve the construct's utility.

The relationship between sleep and cognition in Parkinson's disease: A meta-analysis

It is well established that sleep disorders have neuropsychological consequences in otherwise healthy people. Studies of night-time sleep problems and cognition in Parkinson's disease (PD), however, paint a mixed picture, with many reporting no relationship between sleep problems and neuropsychological performance. This review aimed to meta-analyse this research and to examine the factors underlying these mixed results. A literature search was conducted of published and unpublished studies, resulting in 16 papers that met inclusion criteria. Data were analysed in the domains of: global cognitive function; memory (general, long-term verbal recognition, long-term verbal recall); and executive function (general, shifting, updating, inhibition, generativity, fluid reasoning). There was a significant effect of sleep on global cognitive function, long-term verbal recall, long-term verbal recognition, shifting, updating, generativity, and fluid reasoning. Although there are effects on memory and executive function associated with poor sleep in PD, the effects were driven by a small number of studies. Numerous methodological issues were identified. Further studies are needed reliably to determine whether disturbed sleep impacts on cognition via mechanisms of hypoxia, hypercapnia, sleep fragmentation, chronic sleep debt or decreased REM and/or slow wave sleep in PD, as this may have important clinical implications.

Patterns and predictors of mental health service utilization in people with Parkinson's disease

BACKGROUND

Comorbid psychiatric complications are a common occurrence in Parkinson's disease (PD). However, the majority of people with PD experiencing mental health problems do not receive any professional treatment.

METHOD

A total of 327 Australian adults with PD completed a cross-sectional survey examining patterns of mental health service utilization and predictors of willingness to seek future mental health treatment.

RESULTS

Only 8% of participants were currently engaged in mental health treatment despite elevated levels of depressive and anxiety symptoms. The lifetime service use rate was also low at 24%. Logistic regression analysis showed that, second to prior treatment experience (odds ratio [OR] = 3.28, 95% confidence interval [CI] = 1.46-7.35), having had a discussion about psychological symptoms with a primary PD neurologist was the next most important predictor and tripled the likelihood of an individual being willing to seek future treatment, (OR = 3.01, 95% CI = 1.72-5.27).

CONCLUSION

This study highlights the integral role of the PD neurologist in facilitating awareness and treatment of mental health problems for individuals with PD.

The measurement of psychological literacy: a first approximation

Psychological literacy, the ability to apply psychological knowledge to personal, family, occupational, community and societal challenges, is promoted as the primary outcome of an undergraduate education in psychology. As the concept of psychological literacy becomes increasingly adopted as the core business of undergraduate psychology training courses world-wide, there is urgent need for the construct to be accurately measured so that student and institutional level progress can be assessed and monitored. Key to the measurement of psychological literacy is determining the underlying factor-structure of psychological literacy. In this paper we provide a first approximation of the measurement of psychological literacy by identifying and evaluating self-report measures for psychological literacy. Multi-item and single-item self-report measures of each of the proposed nine dimensions of psychological literacy were completed by two samples (N = 218 and N = 381) of undergraduate psychology students at an Australian university. Single and multi-item measures of each dimension were weakly to moderately correlated. Exploratory and confirmatory factor analyses of multi-item measures indicated a higher order three factor solution best represented the construct of psychological literacy. The three factors were reflective processes, generic graduate attributes, and psychology as a helping profession. For the measurement of psychological literacy to progress there is a need to further develop self-report measures and to identify/develop and evaluate objective measures of psychological literacy. Further approximations of the measurement of psychological literacy remain an imperative, given the construct's ties to measuring institutional efficacy in teaching psychology to an undergraduate audience.

Activities of daily living, depression, and quality of life in Parkinson's disease

This study examined whether activities of daily living (ADL) mediate the relationship between depression and health-related quality of life (HR-QOL) in people with Parkinson's disease (PD). A cross-sectional, correlational research design examined data from 174 participants who completed the Geriatric Depression Scale (GDS-15), Parkinson's Disease Questionnaire-39 (PDQ-39), and Unified Parkinson's Disease Rating Scale-section 2 (UPDRS-section 2 [ADL]). Multiple Regression Analysis (MRA) was used to examine the mediator model. Depression and ADL significantly (p<.001) predicted HR-QOL, and depression significantly (p<.001) predicted ADL. Whilst ADL did not impact on the relationship between depression and HR-QOL, there was a significant (p<.001) indirect effect of depression on HR-QOL via ADL, suggesting both direct and indirect (via ADL) effects of depression on HR-QOL. The magnitude of this effect was moderate (R² = .13). People with PD who report depression also experience greater difficulty completing ADL, which impacts upon their HR-QOL. It is recommended that clinicians adopt a multidisciplinary approach to care by combining pharmacological treatments with psycho/occupational therapy, thereby alleviating the heterogeneous impact of motor and non-motor symptoms on HR-QOL in people with PD.

Personality affects aspects of health-related quality of life in Parkinson's disease via psychological coping strategies

BACKGROUND

Personality traits influence health-related quality of life (HRQoL) in Parkinson's disease (PD). Further, an individual's personality traits can influence the strategies they use to cope with a particular stressful situation. However, in PD, the interplay between personality traits, choice of coping strategy, and their subsequent effect on HRQoL remains unclear.

OBJECTIVE

The objective of this study was to examine whether personality (neuroticism and extraversion) indirectly affects HRQoL through the use of specific psychological coping strategies.

METHODS

One hundred and forty-six patients with PD completed questionnaires on personality (Big Five Aspects Scale; BFAS), coping (Ways of Coping Questionnaire; WCQ), and mood-specific (Depression, Anxiety and Stress Scale; DASS-21) and disease-specific HRQoL (Parkinson's Disease Questionnaire; PDQ-39).

RESULTS

After controlling for gender, age at diagnosis, and age at testing, the emotion-focused coping strategy of escape-avoidance was significantly correlated with neuroticism and certain aspects of HRQoL (cognitive impairment and social support). This suggests that neurotic personality traits may negatively impact on some aspects of HRQoL due to an increased use of escape-avoidance coping strategies. By contrast, planned problem-solving and escape-avoidance coping strategies were both significantly linked to extraversion and interpersonal and mood-related domains of HRQoL. This suggests that extraversion may positively impact on some aspects of HRQoL due to patients adopting greater planned, problem-solving coping strategies, and using fewer escape-avoidance coping mechanisms.

CONCLUSIONS

Psychological interventions aimed at targeting maladaptive coping strategies, such as the use of escape-avoidance coping, may be effective in minimising the negative impact of neuroticism on HRQoL in PD.

A meta-analysis of randomised placebo-controlled treatment trials for depression and anxiety in Parkinson's disease

BACKGROUND

Psychopharmacotherapy currently constitutes the first-line treatment for depression and anxiety in Parkinson's disease (PD) however the efficacy of antidepressant treatments in PD is unclear. Several alternative treatments have been suggested as potentially more viable alternatives including dopamine agonists, repetitive transcranial magnetic stimulation, and cognitive behavioural therapy (CBT).

METHOD

A meta-analysis of randomised placebo-controlled trials for depression and/or anxiety in PD was conducted to systematically examine the efficacy of current treatments for depression and anxiety in PD.

RESULTS

Nine trials were included. There was only sufficient data to calculate a pooled effect for antidepressant therapies. The pooled effect of antidepressants for depression in PD was moderate but non-significant (d = .71, 95% CI = -1.33 to 3.08). The secondary effect of antidepressants on anxiety in PD was large but also non-significant (d = 1.13, 95% CI = -.67 to 2.94). Two single-trials of non-pharmacological treatments for depression in PD resulted in significant large effects; Omega-3 supplementation (d = .92, 95% CI = .15 to 1.69) and CBT (d = 1.57, 95% CI = 1.06 to 2.07), and warrant further exploration.

CONCLUSIONS

There remains a lack of controlled trials for both pharmacological and non-pharmacological treatments for depression and anxiety in PD which limits the conclusions which can be drawn. While the pooled effects of antidepressant therapies in PD were non-significant, the moderate to large magnitude of each pooled effect is promising. Non-pharmacological approaches show potential for depression in PD however more research is required.

Identifying needs, burden, and distress of carers of people with Frontotemporal dementia compared to Alzheimer’s disease

The literature on carers of people with Frontotemporal dementia (FTD) is negligible compared to the vast literature on carers of people with Alzheimer’s disease (AD), and little research has compared the two groups. Research has mainly focused on identifying the behavioural characteristics of people with FTD or AD. The impact of these behaviours on the psychological well-being of carers of people with FTD is relatively unexplored. This study investigated the needs, burden, and extent of depression and anxiety in carers of people with FTD ( n = 30) compared to carers of people with AD ( n = 30). Findings indicated that needs of carers of people with FTD were significantly higher than those of the carers of people with AD. The elevated needs were related to the younger onset of FTD, financial dissatisfaction, typical FTD characteristics, and access to appropriate services, information and support. Results also suggested that female carers were more likely to report a greater severity and impact of disruptive symptoms associated with FTD. No significant differences were found between the two groups on carers’ levels of burden, depression or anxiety. In order to address the needs of carers of people with FTD, we recommend specific educational and support programs, raising community awareness and understanding, and tailoring existing domiciliary services and activities for people with FTD.

The role of early fine and gross motor development on later motor and cognitive ability

The aim of this study was to determine whether information obtained from measures of motor performance taken from birth to 4 years of age predicted motor and cognitive performance of children once they reached school age. Participants included 33 children aged from 6 years to 11 years and 6 months who had been assessed at ages 4 months to 4 years using the ages and stages questionnaires (ASQ: [Squires, J. K., Potter, L., & Bricker, D. (1995). The ages and stages questionnaire users guide. Baltimore: Brookes]). These scores were used to obtain trajectory information consisting of the age of asymptote, maximum or minimum score, and the variance of ASQ scores. At school age, both motor and cognitive ability were assessed using the McCarron Assessment of Neuromuscular Development (MAND: [McCarron, L. (1997). McCarron assessment of neuromuscular development: Fine and gross motor abilities (revised ed.). Dallas, TX: Common Market Press.]), and the Wechsler Intelligence Scale for Children-Version IV (WISC-IV: [Wechsler, D. (2004). WISC-IV integrated technical and interpretive manual. San Antonio, Texas: Harcourt Assessment]). In contrast to previous research, results demonstrated that, although socio-economic status (SES) predicted fine motor performance and three of four cognitive domains at school age, gestational age was not a significant predictor of later development. This may have been due to the low-risk nature of the sample. After controlling for SES, fine motor trajectory information did not account for a significant proportion of the variance in school aged fine motor performance or cognitive performance. The ASQ gross motor trajectory set of predictors accounted for a significant proportion of the variance for cognitive performance once SES was controlled for. Further analysis showed a significant predictive relationship for gross motor trajectory information and the subtests of working memory and processing speed. These results provide evidence for detecting children at risk of developmental delays or disorders with a parent report questionnaire prior to school age. The findings also add to recent investigations into the relationship between early motor development and later cognitive function, and support the need for ongoing research into a potential etiological relationship.

Limb and gender differences in the development of coordination in early infancy

Young infants produce a variety of spontaneous arm and leg movements in the first few months of life. Coordination of leg joints has been extensively investigated, whereas arm joint coordination has mainly been investigated in the sitting position in the context of early reaching and grasping. The current study investigated arm and leg joint coordination of movements produced in the supine position in 10 fullterm infants aged 6, 12 and 18 weeks. Longitudinal comparisons within limbs (intralimb) as well as between limbs (interlimb, ipsilateral and contralateral) were made as well as an exploration of differences in the development for boys and girls. The relationship between the joint angles was examined by measuring pair-wise cross-correlation functions for the angular displacement curves of the leg (hip, knee and ankle) and arm (shoulder, elbow and wrist) joints of both the right and left side. Both the arms and legs were found to follow a similar pattern of intralimb coordination, although the leg joints were more tightly coupled than the arm joints, particularly the proximal with the middle joint. In support of earlier findings, differences in the development of the right and left side were identified. In addition, gender differences in joint coordination were found for both intralimb and interlimb coordination. This contrasts with the view that gender differences in motor development may be primarily a result of environmental influences.

Analysis and classification of the rotational growth pattern without implants

A morphogenetic classification of malocclusion based upon a group of implant patients is applied to a group of patients without implants. This allows an analysis of the general trend of the rotational growth Pattern of the jaws without the use of implants.

The maxillary rotation: Its relation to the cranial base and the mandibular corpus. An implant study

A material of 22 patients with metallic implants was used in a longitudinal study, based on lateral head-plates, of the relationship between: 1) the maxillary rotation and the cranial base 2) the maxillary rotation and the different mandibular rotations. No connection has been found between the variation of the maxillary rotation and the growth of the cranial base. The correlation between the maxillary and the mandibular rotations is the highest when the rotation of the corpus is considered. A strong correlation is found between the variation of the condylar growth direction and the variation of the maxillary rotation.

Direction and intensity of mandibular rotation in the sagittal adjustment during growth of the jaws

A material of 22 patients with metallic implants in both jaws has been used to study, longitudinally on lateral headplates, the relationship between the degree of mandibular rotation, the difference in amount of growth of both jaws, represented by the value (E), and the sagittal intermaxillary relationship (G). It has been established that the variation of sagittal intermaxillary relationship and the variation of the degree of mandibular rotation are two phenomena presenting a "balance mechanism" when related to the value (E). The different combinations of these three variables during mandibular growth are proposed, represented in diagrams. This study reveals that several possible mandibular responses correspond to a single given initial condition.

Operational definitions of mandibular morphogenetic and positional rotations

A material of 30 patients with metallic implants was used in a longitudinal study, based on lateral headplates, of the mandibular rotational pattern. The complexity of the rotational phenomenon in the mandibular rotation has necessitated the proposal of some operational definitions: morphogenetic and positional rotations of the mandible. A relationship has been established between the variation of the gonial angle and the variation of both morphogenetic and positional rotations of the mandible. A relationship has been established between the variation of the condylar growth direction and the variation of both morphogenetc and positional rotations of the mandible: this relationship is the strongest when the morphogenetic rotation of the corpus is considered.

Maxillary rotation during human growth: annual variation and correlations with mandibular rotation. A metal implant study

For a longitudinal study of the maxillary rotation, based on lateral headplates, a material of 22 patients with metallic implants in both jaws has been used. It has been established that the degree of maxillary rotation shows variations in direction and in intensity each year. It is smaller, in absolute value, than the degree of mandibular rotation. Due to the fact the direction of the maxillary and mandibular rotations are not always the same, it appears that the interaction between the maxillary and mandibular rotations plays an important role in the vertical and sagittal relationships of both jaws.