Background-Recent studies indicate an increased frequency of mutations in the gene for Gaucher disease, glucocerebrosidase (GBA), among patients with Parkinson disease. An international collaborative study was conducted to ascertain the frequency of GBA mutations in ethnically diverse patients with Parkinson disease.

Until recently, gait was generally viewed as a largely automated motor task, requiring minimal higher-level cognitive input. Increasing evidence, however, links alterations in executive function and attention to gait disturbances. This review discusses the role of executive function and attention in healthy walking and gait disorders while summarizing the relevant, recent literature. We describe the variety of gait disorders that may be associated with different aspects of executive function, and discuss the changes occurring in executive function as a result of aging and disease as well the potential impact of these changes on gait. The attentional demands of gait are often tested using dual tasking methodologies. Relevant studies in healthy adults and patients are presented, as are the possible mechanisms responsible for the deterioration of gait during dual tasking. Lastly, we suggest how assessments of executive function and attention could be applied in the clinical setting as part of the process of identifying and understanding gait disorders and fall risk. © 2007 Movement Disorder Society Key words: gait; executive function; attention; Parkinson's disease; Alzheimer's disease; aging; dual task; review article The relationship between higher-level cognitive function and gait disturbances has received considerable attention in recent years. Gait is no longer considered as merely an automated motor activity that utilizes minimal higher-level cognitive input. Instead, the multifaceted neuropsychological influences on walking and the interactions between the control of mobility and related behaviors are increasingly appreciated. This is manifest in part by an individual's awareness of a destination, the ability to appropriately control the limb movements that produce gait, and the ability to navigate within often complex environs to successfully reach the desired location. Studies on cognitive function and gait now include many areas of research, ranging from physiology and biomechanics to brain mapping, physics and neuropsychology. For example, imaging studies have demonstrated frontal and parietal activity during locomotion. 1,2 This review covers the importance and relevance of two specific cognitive functions, executive function (EF) and attention, to the performance of gait during normal walking, as well as in aging and in pathological conditions. We review the physiology underlying these cognitive processes, describe the clinical findings and consequences of these relationships and discuss the physiological mechanisms that are brought into play. Finally, we summarize the implications of these associations for the daily lives of individuals affected by impaired function of one or more or these elements and provide suggestions for applying these insights to augment the diagnosis of gait disorders in the clinic. This review article is based on a systematic literature search for reviews and trials reported in English in the electronic databases of Medline and Psychinfo up to April, 2007. Relevant s...

The Movement Disorder Society Task Force for Rating Scales for Parkinson's disease (PD) prepared a critique of the Hoehn and Yahr scale (HY). Strengths of the HY scale include its wide utilization and acceptance. Progressively higher stages correlate with neuroimaging studies of dopaminergic loss, and high correlations exist between the HY scale and some standardized scales of motor impairment, disability, and quality of life. Weaknesses include the scale's mixing of impairment and disability and its non-linearity. Because the HY scale is weighted heavily toward postural instability as the primary index of disease severity, it does not capture completely impairments or disability from other motor features of PD and gives no information on nonmotor problems. Direct clinimetric testing of the HY scale has been very limited, but the scale fulfills at least some criteria for reliability and validity, especially for the midranges of the scale (Stages 2-4). Although a "modified HY scale" that includes 0.5 increments has been adopted widely, no clinimetric data are available on this adaptation. The Task Force recommends that: (1) the HY scale be used in its original form for demographic presentation of patient groups; (2) when the HY scale is used for group description, medians and ranges should be reported and analysis of changes should use nonparametric methods; (3) in research settings, the HY scale is useful primarily for defining inclusion/exclusion criteria; (4) to retain simplicity, clinicians should "rate what you see" and therefore incorporate comorbidities when assigning a HY stage; and (5) because of the wide usage of the modified HY scale with 0.5 increments, this adaptation warrants clinimetric testing. Without such testing, however, the original five-point scales should be maintained.

Freezing of gait (FoG) is a unique and disabling clinical phenomenon characterised by brief episodes of inability to step or by extremely short steps that typically occur on initiating gait or on turning while walking. Patients with FoG, which is a feature of parkinsonian syndromes, show variability in gait metrics between FoG episodes and a substantial reduction in step length with frequent trembling of the legs during FoG episodes. Physiological, functional imaging, and clinical-pathological studies point to disturbances in frontal cortical regions, the basal ganglia, and the midbrain locomotor region as the probable origins of FoG. Medications, deep brain stimulation, and rehabilitation techniques can alleviate symptoms of FoG in some patients, but these treatments lack efficacy in patients with advanced FoG. A better understanding of the phenomenon is needed to aid the development of effective therapeutic strategies.