Correlates of Gait Speed Among Older Adults From 6 Countries: Findings From the COSMIC Collaboration

BACKGROUND

Few studies have compared gait speed and its correlates among different ethnogeographic regions. The goals of this study were to describe usual and rapid gait speed, and identify their correlates across Australian, Asian, and African countries.

METHODS

We used data from 6 population-based cohorts of adults aged 65+ from 6 countries and 3 continents (N = 6 472), with samples ranging from 231 to 1 913. All cohorts are members of the Cohort Studies of Memory in an International Consortium collaboration. We investigated whether clinical (body mass index [BMI], hypertension, stroke, apolipoprotein status), psychological (cognition, mood, general health), and behavioral factors (smoking, drinking, physical activity) correlated with usual (N = 4 cohorts) and rapid gait speed (N = 3 cohorts) similarly across cohorts. Regression models were controlled for age, sex, and education, and were sex-stratified.

RESULTS

Age- and sex-standardized usual gait speed means ranged from 0.61 to 1.06 m/s and rapid gait speed means ranged from 1.16 to 1.64 m/s. Lower BMI and better cognitive function consistently correlated with faster gait speed in all cohorts. Less consistently, not having hypertension and greater physical activity engagement were associated with faster gait speed. Associations with mood, smoking, and drinking were largely nonsignificant. These patterns were not attenuated by demographics. There was limited evidence that the associations differed by sex, except physical activity, where the greater intensity was associated with usual gait among men but not women.

CONCLUSIONS

This study is among the first to describe the usual and rapid gait speeds across older adults in Africa, Asia, and Australia.

We think you can dance! A pilot randomised controlled trial of dance for nursing home residents with moderate to severe dementia

OBJECTIVES

To evaluate the feasibility of a dance program for people with moderate to severe dementia living in nursing homeswith regards to recruitment and retention, assessment tools, intervention safety, attendance and engagement.

DESIGN

Pilot randomised controlled trial with assessments at weeks 0, 16 and 32.

SETTING

A nursing home in Sydney, Australia.

INTERVENTIONS

Experienced dance teachers conducted dance groups (intervention) or music appreciation and socialisation groups (control) for 45min, three times a week for 16 weeks.

MAIN OUTCOME MEASURES

Descriptive statistics for recruitment and retention, adverse events and attendance and engagement.

RESULTS

Recruitment was smooth, attrition was17% over 32 weeks. Engagement during the sessions was high, and no serious falls or behavioural incidents occurred. Average attendance was poorer than anticipated for dance groups (67%) in comparison to music groups (89%). A ceiling effect on the Severe Impairment Battery and the logistical challenges of the Clinical Global Impression of Change meant they may not be optimal tools.

CONCLUSIONS

It is feasible to conduct a study of group dance for people with moderate to severe dementia in residential care. Choice of attention control condition should be reconsidered.

Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53949)

General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53,949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P=3.93 × 10(-9), MIR2113; rs17522122, P=2.55 × 10(-8), AKAP6; rs10119, P=5.67 × 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P=1 × 10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N=6617) and the Health and Retirement Study (N=5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.

The prevalence of "cognitive impairment no dementia" in community-dwelling elderly: a pilot study

OBJECTIVE

To determine the prevalence of "cognitive impairment no dementia" (CIND) and "amnestic mild cognitive impairment" (aMCI) in a population sample of 70-79-year-olds and the risk factors for CIND.

METHOD

Cross sectional population survey.

SETTING

Sutherland Shire, Sydney, Australia.

SUBJECTS

150 community-dwelling 70-79-year-olds were screened by telephone, 42 of whom were assessed at home.

MEASURES

Demographics, subjective ratings of physical and emotional health and memory, cardiovascular risk factors, medications, the Mini-Mental State Examination, Boston Naming Test, Trail Making Tests A and B, Block Design, Rey Auditory Verbal Learning Test (RAVLT), Visual Reproduction, Logical Memory, letter and category fluency, the National Adult Reading Test (NART), the Geriatric Depression Scale (GDS) and the "state" section of the State-Trait Anxiety Inventory (STAI-S).

RESULTS

From the 400 subjects contacted initially, 150 consented to be interviewed and 131 eligible subjects were recruited. Of a 1-in-3 random sample of 42 subjects assessed at home, 14 (33.3%) subjects met criteria for CIND, 1 (2.4%) had possible dementia and the 27 remaining (64.3%) were cognitively normal. Four (9.5%) met criteria for aMCI. Subjects with CIND were older, had lower ranking occupations and were less likely to be currently working than those classified as cognitively normal. Ten subjects with CIND did not meet criteria for aMCI because they lacked subjective memory impairment (n = 3) or had cognitive deficits other than memory (n = 7). All subjects with aMCI met criteria for CIND.

CONCLUSIONS

One-third of individuals in this population sample met criteria for CIND. CIND is a broader definition than aMCI. Further research is needed to determine the longitudinal course and clinical utility of these definitions of cognitive impairment.

Experimental investigation of stochastic pulsation and formation of light bullets with megagauss magnetic fields by an intense laser pulse propagating in a preionized plasma

The generation of extremely stable light bullets in a preformed plasma near critical density has been observed experimentally during the interaction of intense picosecond laser beam with a metallic target in air. Optical probing measurements indicate the formation of pulsating channels, typically of about 5 microm in diameter, directed towards a heating laser beam, as well as of disconnected massive plasma blocks moving also towards the laser beam. The velocities of the dense plasma blocks reach the values of 4.5x10(8) cm/s. The blocks are stable during their acceleration and propagation in air. Self-generated magnetic fields up to 4-7 MG were observed by means of the Faraday rotation of a probe laser beam.

HIV risk-taking behaviour among injecting drug users currently, previously and never enrolled in methadone treatment

This study compares the injecting and sexual risk-taking behaviour among injecting drug users (IDUs) currently, previously and never enrolled in methadone maintenance treatment (MMT). All subjects had injected during the 6 months prior to the day of interview. The current MMT group showed significantly lower injecting risk-taking behaviour subscale scores on the HIV Risk-taking Behaviour Scale (HRBS) of the Opiate Treatment Index than the previous MMT and non-MMT groups together. The current MMT group differed from the other two groups in the frequency of injecting and cleaning of injection equipment with bleach. There was no difference between the current MMT group and the other two groups combined in sexual risk-taking behaviour scores on the HRBS. There were no differences between the previous MMT and non-MMT groups in injecting and sexual risk-taking behaviour. HIV seroprevalence was low and there was no difference in seroprevalence between groups. Thus, IDUs currently enrolled in MMT are at reduced risk for HIV infection when compared with IDUs who have previously or never been enrolled in MMT. However, the absence of a difference between the current MMT and other two groups in frequency of sharing behaviours suggests the need for additional strategies among MMT clients to reduce needle-sharing. Possible strategies include the application of relapse prevention interventions and the availability of sterile injecting equipment in MMT clinics. Further research is needed to identify factors which increase attraction and retention of IDUs to MMT.

Controlled evaluation of a brief intervention for HIV prevention among injecting drug users not in treatment

This study evaluated the effectiveness of a brief intervention (BI), a one-session motivational interview, in reducing HIV risk-taking behaviour among injecting drug users (IDU) not enrolled in any form of treatment for drug dependence. IDU were randomly assigned to either BI or a non-intervention control condition (NIC). One hundred and twenty-one subjects were successfully contacted for a 3-month follow-up and 88 subjects were followed up at 6 months. There were significant reductions for the sample as a whole for injecting risk-taking subscale scores on the HIV Risk-taking Behaviour Scale between pre-treatment and follow-up. There was no significant change in sexual risk-taking behaviour. There were no significant differences between groups on any measure at 3- and 6-month follow-up. There are a number of possible reasons why the sample as a whole showed significant improvements from initial to follow-up assessments. It is possible that, having had their attention directed to their risk-taking behaviour, subjects attempted to reduce their injecting risk-taking behaviour. If this is the case and subjects in the NIC condition can be considered as having received a BI, this suggests that BIs involving a personal risk assessment are effective in reducing risk behaviours associated with injecting. However, this suggestion could only be confirmed by comparison with a non-assessment control group.

Drug use and HIV risk-taking behaviour among injecting drug users not currently in treatment in Sydney, Australia

This study investigated the drug use patterns and HIV risk-taking behaviour of 200 injecting drug users (IDU) not currently in treatment in Sydney, Australia. Although there was low HIV seroprevalence, unsafe injecting and sexual practices were common. Variables that were predictive of injecting risk-taking were higher level of heroin use, sexual relationship with an IDU and greater polydrug use. Two variables were predictive of sexual risk-taking: higher level of hallucinogen use and sexual relationship with an IDU. Female subjects were significantly more likely to have an IDU sexual partner. A higher level of cannabis use was associated with greater polydrug use and a higher level of amphetamine use was associated with greater use of opiates other than heroin. The findings are discussed in terms of the need for interventions aimed towards reducing sexual risk-taking among users of hallucinogens and towards reducing injecting and sexual risk-taking among IDU and their sexual partners. The potential difficulty in producing behaviour change among polydrug users is highlighted.