Biomedical subjects

Nicole J Rinehart

Publications and source records attributed to Nicole J Rinehart.

9 recordsLinked to original sources

PubMed2006

Gait function in high-functioning autism and Asperger's disorder : evidence for basal-ganglia and cerebellar involvement?

Gait abnormalities have been widely reported in individuals with autism and Asperger's disorder. There is controversy as to whether the cerebellum or the basal-ganglia frontostriatal regions underpin these abnormalities. This is the first direct comparison of gait and upper-body postural features in autism and Asperger's disorder. Clinical and control groups were matched according to age, height, weight, performance, and full scale IQ. Consistent with Hallet's (1993) cerebellar-gait hypothesis, the autistic group showed significantly increased stride-length variability in their gait in comparison to control and Asperger's disorder participants. No quantitative gait deficits were found for the Asperger's disorder group. In support of Damasio and Maurer's (1982) basal-ganglia frontostriatal-gait hypothesis, both clinical groups were rated as showing abnormal arm posturing, however, only the Asperger's group were rated as significantly different from controls in terms of head and trunk posturing. While DSM-IV-TR suggests that Asperger's disorder, but not autism, is associated with motoric clumsiness, our data suggest that both clinical groups are uncoordinated and lacking in motor smoothness. Gait differences in autism and Asperger's disorder were suggested to reflect differential involvement of the cerebellum, with commonalities reflecting similar involvement of the basal-ganglia frontostriatal region.

Asperger Syndrome↗

PubMed2006

An examination of movement kinematics in young people with high-functioning autism and Asperger's disorder: further evidence for a motor planning deficit.

This paper examines upper-body movement kinematics in individuals with high-functioning autism (HFA) and Asperger's disorder (AD). In general, the results indicate that HFA is more consistently associated with impaired motoric preparation/initiation than AD. The data further suggest that this quantitative difference in motor impairment is not necessarily underpinned by greater executive dysfunction vulnerability in autism relative to AD. Quantitative motoric dissociation between autism and AD may have down-stream effects on later stages of movement resulting in qualitative differences between these disorder groups, e.g. "motor clumsiness" in AD versus "abnormal posturing" in autism. It will be important for future research to map the developmental trajectory of motor abnormalities in these disorder groups.

Adolescent↗

PubMed2006

Movement-related potentials in high-functioning autism and Asperger's disorder.

Autism and Asperger's disorder (AD) are neurodevelopmental conditions that affect cognitive and social-communicative function. Using a movement-related potential (MRP) paradigm, we investigated the clinical and neurobiological issue of 'disorder separateness' versus 'disorder variance' in autism and AD. This paradigm has been used to assess basal ganglia/supplementary motor functioning in Parkinson's disease. Three groups (high functioning autism [HFA]: 16 males, 1 female; mean age 12y 5mo [SD 4y 4mo]; AD: 11 males, 2 females; mean age 13y 5mo [SD 3y 8mo]; comparison group: 13 males, 8 females; mean age 13y 10mo [SD 3y 11mo]) completed a cued motor task during electroencephalogram recording of MRPs. The HFA group showed reduced peak amplitude at Cz, indicating less activity over the supplementary motor area during movement preparation. Although an overall significant between-group effect was found for early slope and peak amplitude, sub-analysis revealed that the group with AD did not differ significantly from either group. However, it is suggested that autism and AD may be dissociated on the basis of brain-behaviour correlations of IQ with specific neurobiological measures. The overlap between MRP traces for autism and Parkinson's disease suggests that the neurobiological wiring of motor functioning in autism may bypass the supplementary motor area/primary motor cortex pathway.

Adolescent↗

PubMed2006

Gait function in newly diagnosed children with autism: Cerebellar and basal ganglia related motor disorder.

We investigated gait in newly diagnosed children with autism. From our previous study with 6- to 14-year-olds, we hypothesized that motor symptoms indicative of basal ganglia and cerebellar dysfunction would appear across the developmental trajectory of autism. Two groups were recruited: children with autism (eight males, three females; mean age 5 y 10 mo [SD 9 mo]; range 4 y 4 mo-6 y 9 mo) and a comparison group of typically developing children (eight males, three females; mean age 5 y 9 mo [SD 1 y 1 mo]; range 4 y 3 mo-7 y 2 mo). The GAITRite Walkway was used to gather data from average gait and intra-walk measurements. Experienced physiotherapists analyzed gait qualitatively. Groups were matched according to age, height, weight, and IQ; although not statistically significant, IQ was lower in the group with autism. Spatiotemporal gait data for children with autism were compatible with findings from patients with cerebellar ataxia: specifically, greater difficulty walking along a straight line, and the coexistence of variable stride length and duration. Children with autism were also less coordinated and rated as more variable and inconsistent (i.e. reduced smoothness) relative to the comparison group. Postural abnormalities in the head and trunk suggest additional involvement of the fronto-striatal basal ganglia region. Abnormal gait features are stable across key developmental periods and are, therefore, promising for use in clinical screening for autism.

Adolescent↗

PubMed2006

Pseudo-random number generation in children with high-functioning autism and Asperger's disorder: further evidence for a dissociation in executive functioning?

The repetitive, stereotyped and obsessive behaviours, which are core diagnostic features of autism, are thought to be underpinned by executive dysfunction. This study examined executive impairment in individuals with autism and Asperger's disorder using a verbal equivalent of an established pseudo-random number generating task. Different patterns of disinhibition emerged in the autism (n = 12) and Asperger's disorder (n = 12) groups. Consistent with previous research, the autism group repeated single numbers (e.g. 2, 2, 2) more frequently than the control group. In contrast to past research suggesting intact executive abilities, this study found that the Asperger's disorder group generated more repetitive number patterns (e.g. 45, 45) than the controls. Executive functioning in children with Asperger's disorder may be particularly vulnerable to a lack of visual cueing and concrete rules. Qualitative differences in executive dysfunction between these groups may implicate differential disruption within the fronto-striatal circuitry.

Asperger Syndrome↗

PubMed2005

Autism and Asperger's disorder: are they movement disorders involving the cerebellum and/or basal ganglia?

Autism and Asperger's disorder (AD) are childhood developmental disorders of unknown aetiology. Autism and AD share several behavioural features, and it is not clear whether they are distinct disorders or variants of the same disorder. Recent studies indicate that disordered movement may be another feature of autism and AD, and that this may reflect dysfunction within the frontostriatal and/or cerebellar motor circuits. While disordered movement in autism and AD has been examined in a variety of ways, it is relatively under-researched compared to the cognitive, affective, and behavioural disturbances seen in these disorders. This review examines the role of the frontostriatal and cerebellar motor systems in the behavioural features of autism and AD, with gait as a proxy, and discusses difficulties with their diagnosis and their possible pathogenesis.

Animals↗

PubMed2002

Lateralization in individuals with high-functioning autism and Asperger's disorder: a frontostriatal model.

Neurobiological and behavioural studies of possible left hemisphere dysfunction in autism have generated conflicting results. Left hemisphere dysfunction may manifest in autism only in tasks that invoke executive functions. Moreover, left hemisphere dysfunction may underpin autism but not Asperger's disorder. We thus aimed to systematically investigate reports of anomalous lateralization in individuals with high-functioning autism and Asperger's disorder. Two of the tasks were sensitive to executive dysfunction: a serial choice reaction-time task and a Posner-type paradigm; the remaining tasks instead investigated aspects of perceptual lateralisation. Compared with age- and IQ-matched controls, the autism group displayed deficiencies in right hemispace (and by implication, left hemisphere) performance on both executive function tasks; however, this group demonstrated normal lateralization effects on the nonexecutive, visual-perceptual tasks. In contrast, the Asperger's disorder group showed similar laterality effects to their age- and IQ-matched controls on both executive and nonexecutive function tasks. The etiological relevance of this neurobehavioral dissociation between high-functioning autism and Asperger's disorder was discussed; in particular, it was suggested that the period where dominance shifts from right to left hemisphere is important in whatever process might dictate the emergence of either autism or Asperger's disorder.

Adolescent↗

PubMed2002

Random number generation in autism.

This study explored the ability of individuals with autism to generate a unique series of digits. Fourteen low-functioning individuals with autism, 14 intellectually disabled individuals, and 14 postgraduate university students generated a series of pseudo-random digits. Individuals with autism were more likely to repeat previous digits than were either of the control groups. The normal control group, however, was less likely to attempt cycling through all digits before repeating. Accordingly, low-functioning individuals with autism may exhibit a short-fall in response inhibition. This finding supports the executive dysfunction theory of autism.

Adolescent↗

PubMed2002

A clinical and neurobehavioural review of high-functioning autism and Asperger's disorder.

OBJECTIVE: To compare, contrast and review clinical and neuropsychological studies of high-functioning autism and Asperger's disorder. METHOD: This paper reviews past and contemporary conceptualizations of autism and Asperger's disorder, together with epidemiological information, genetic and neurobehavioural findings. This paper focuses on neurobehavioural studies, in particular, executive functioning, lateralization, visual-perceptual and motor processing, which have provided an important source of information about the potential neurobiological dissociation that may exist between autism and Asperger's disorder. RESULTS: The clinical profiles of autism and Asperger's disorder contain a mixture of psychiatric and neurological symptoms: for example, movement abnormalities (i.e. stereotyped behaviours, hand flapping, toe walking, whole-body movements), atypical processing of parts and wholes, verbal and non-verbal deficits, ritualistic/compulsive behaviour, disturbances in reciprocal social interaction and associated depression and anxiety. The considerable clinical overlap between autism and Asperger's disorder has led many to question whether Asperger's disorder is merely a mild form of autism, or whether it should be considered as a separate clinical entity. CONCLUSION: In light of the growing body of epidemiological information, genetic, and neurobehavioural evidence that distinguishes autism from Asperger's disorder, it is premature to rule out the possibility that these disorders may be clinically, and possibly neurobiologically separate.

Adolescent↗