Correlation of frailty assessment metrics in one-year follow-up of aged care residents: a sub-study of a randomised controlled trial

INTRODUCTION

Frailty is increasingly recognised as a dynamic syndrome, with multiple causes, dimensions and consequences. There is little understanding of how those frailty assessment metrics interact over time. The aim of this study was to describe the longitudinal correlation between five frailty metrics, namely multimorbidity, muscular strength, mood alterations, cognitive capacity, and functional capacity in a cohort study of aged care (nursing home) residents.

METHODS

248 aged care residents with Frailty Index at baseline of < 0.4 and no dementia were followed for 12 months. A multimorbidity score and an activity of daily living limitation score were created using individual items of the Frailty Index. Muscular strength was measured by grip strength. Cognitive capacity was measured using the Montreal Cognitive Assessment (MoCA) test. Mood alterations were measured using the anxiety/depression screening question from EQ-5D. We analysed the inter-individual correlation at baseline, association between baseline and future change, and within-individual correlation at baseline, 6 and 12 months.

RESULTS

Population analysis shows that metrics were not associated at baseline. All of the studied metrics at baseline were associated with change in 12 months, with the exception of anxiety/depression scores. Pairwise within-individual correlation was strong between MoCA and grip strength (0.13, p = 0.02) and activity of daily living (- 0.48, p < 0.001), and between activities of daily living and multimorbidity index (0.28, p < 0.001). No within-individual correlation was found between anxiety depression score and other metrics.

CONCLUSION

The results suggest an interdependence between comorbidities, physical capacity, cognition and activities of daily living in aged care residents. Comprehensive measurement of frailty-related metrics may provide improved understanding of frailty progression at later life stages.

Genomic structure and expression analysis of the spastic paraplegia gene, SPG7

SPG7 is a newly identified gene involved in an autosomal recessive form of hereditary spastic paraplegia (HSP), a genetically heterogeneous group of neurodegenerative disorders. This gene encodes a protein characterized as a nuclear-encoded mitochondrial metalloprotease. The present report describes the genomic structure of the SPG7 gene. It is organized into 17 exons ranging from 78 to 242 bp and spans approximately 52 kb within three overlapping cosmids. The exon/intron boundaries and all splice junctions are consistent with the published consensus sequences for donor and acceptor sites. The provided genomic structure of SPG7 should facilitate the screening for mutations in this gene in patients with HSP and other related mitochondrial disease syndromes. SPG7 has been mapped to chromosome 16q24.3, a region of frequent loss of heterozygosity (LOH) seen in sporadic breast and prostate cancer. We have performed single-strand conformation polymorphism analysis of ten exons of this gene in a number of sporadic breast cancer samples showing LOH at 16q24.3. No mutations were detected; only single nucleotide polymorphisms were observed in exon 11, intron 7, intron 10 and intron 12. An expression analysis study has revealed the differential expression of SPG7 mRNA in various tissues and at different developmental stages.

The Batten disease gene product (CLN3p) is a Golgi integral membrane protein

Batten disease (juvenile neuronal ceroid lipofuscinosis) is a recessive neurodegenerative disorder of childhood. The gene, CLN3, was recently identified and found to encode a novel 438 amino acid protein of unknown function. In order to gain insight into the function of the Batten disease protein (CLN3p), we investigated its subcellular localization. Protein constructs incorporating CLN3p fused to the green fluorescence protein or an eight amino acid peptide tag were transiently expressed in fibroblasts, HeLa and COS-7 cells. A juxtanuclear, asymmetric localization pattern was observed that correlated with the Golgi apparatus in all three cell types. However, a proportion of transiently transfected cells exhibited a punctate vesicular distribution throughout the cytoplasm in addition to or without the Golgi localization. In order to account for localization patterns arising from intracellular protein transport disruption due to exaggerated overexpression in transiently transfected cells, we isolated a stably transfected cell line expressing only one copy of the CLN3 -GFP DNA construct. Fluorescence and biochemical analyses using this cell line demonstrated that CLN3p is an integral membrane protein that localizes primarily in the Golgi apparatus. The functional implications of this finding are discussed.