Post-Cueing Deficits with Maintained Cueing Benefits in Patients with Parkinson's Disease Dementia

In Parkinson's disease (PD), internal cueing mechanisms are impaired leading to symptoms like hypokinesia. However, external cues can improve movement execution by using cortical resources. These cortical processes can be affected by cognitive decline in dementia. It is still unclear how dementia in PD influences external cueing. We investigated a group of 25 PD patients with dementia (PDD) and 25 non-demented PD patients (PDnD) matched by age, sex, and disease duration in a simple reaction time task using an additional acoustic cue. PDD patients benefited from the additional cue in similar magnitude as did PDnD patients. However, withdrawal of the cue led to a significantly increased reaction time in the PDD group compared to the PDnD patients. Our results indicate that even PDD patients can benefit from strategies using external cue presentation but the process of cognitive worsening can reduce the effect when cues are withdrawn

Plasma Ceramide and Glucosylceramide Metabolism Is Altered in Sporadic Parkinson's Disease and Associated with Cognitive Impairment: A Pilot Study

BACKGROUND: Mutations in the gene coding for glucocerebrosidase (GBA), which metabolizes glucosylceramide (a monohexosylceramide) into glucose and ceramide, is the most common genetic risk factor for sporadic Parkinson's disease (PD). GBA mutation carriers are more likely to have an earlier age of onset and to develop cognitive impairment and dementia. We hypothesized that plasma levels of lipids involved in ceramide metabolism would also be altered in PD non-GBA mutation carriers and associated with worse cognition. METHODS: Plasma ceramide, monohexosylceramide, and lactosylceramide levels in 26 cognitively normal PD patients, 26 PD patients with cognitive impairment or dementia, and 5 cognitively normal non-PD controls were determined by LC/ESI/MS/MS. RESULTS: Levels of all lipid species were higher in PD patients versus controls. Among PD patients, levels of ceramide C16:0, C18:0, C20:0, C22:0, and C24:1 and monohexosylceramide C16:0, C20:0 and C24:0 species were higher (all P<0.05) in those with versus without cognitive impairment. CONCLUSION: These results suggest that plasma ceramide and monohexosylceramide metabolism is altered in PD non-GBA mutation carriers and that higher levels are associated with worse cognition. Additional studies with larger sample sizes, including cognitively normal controls, are needed to confirm these findings

Phylogenetic relationships of species of Raymunida (Decapoda: Galatheidae) based on morphology and mitochondrial cytochrome oxidase sequences, with the recognition of four new species

19 pages.-- RECEIVED: 10 April 2000, ACCEPTED: 8 November 2000.The species of the genus Raymunida from the Pacific and Indian oceans are revised using morphological characters and the mitochondrial cytochrome oxidase subunit I sequences. Four new species are described (R. confundens, R. dextralis, R. erythrina, and R. insulata), and the status of R. bellior and R. elegantissima are revised. The species of Raymunida can be identified by subtle morphological characters, which match differences in mitochondrial nucleotide sequences. Therefore, the sequence divergences confirm the specific and phylogenetic value of some morphological characters (e.g., length of the mesial spine on the basal antennal segment, length of the walking legs). Furthermore, they confirm the importance of the color pattern as a diagnostic character. The widespread species (R. elegantissima), known from the Philippines to Fiji, shows minimal divergence between specimens from different localities (maximum of 3 nucleotide differences or 0.2% mean divergence). The phylogenetic reconstruction agreed with the monophyletic condition of Raymunida and its differentiation with respect to the genus Munida (in which Raymunida species had previously been included) and Agononida.Peer reviewe