Clinical Drug Experience Knowledgebase

Investigating the Effects of Omega-3 Fatty Acid Multinutrient Supplement and Exercise on Mobility and Cognition in Older Women

Design and Setting:

The study is a randomized semi-blinded, placebo-controlled trial in females aged 60 years and over. The study examines the effects of a high docosahexaenoic acid omega-3 PUFA multi-nutrient dietary supplement and aerobic exercise, both on their own and in combination, on outcomes related to mobility and cognition. All measurements and data collection, as well as the aerobic exercise, take place at the same study site (Bournemouth University, United Kingdom), with participants instructed to consume the dietary supplement at home.

Blinding Randomization and Allocation:

The dietary supplements are packed in identical containers and coded by the Principal Investigator, who has no involvement in the data collection. Omega-3 PUFA capsules have a distinct odor, therefore a small amount of fish oil is added to the placebo capsules to help maintain blinding. A stratified block randomization design is followed with stratification based on frailty classification of non-frail or pre-frail, followed by permuted block randomization. Randomization is achieved by creating a computer-generated list of numbers consisting of four blocks for each stratum referred to without specification of the intervention group (e.g., A, B, C, and D). The list is generated and stored by the Principal Investigator. Due to the nature of the exercise intervention participants are only be blinded to the dietary intervention; however, the experimenters are blinded to the exercise group allocations.

Participants:

Participants are recruited through local newspaper advertisements and public engagements in Bournemouth, U.K. The public advertisements include a brief study description as well as the contact details for the research team. Those who are interested receive a participant information document including the design, procedure, benefits, and risks of the study. Before any data is collected, all participants provide signed written informed consent forms.

All participants are screened to assess frailty status, according to the Fried et al. (2001) criteria. The criteria include low muscle strength, self-reported exhaustion, slowed gait speed, low levels of physical activity, and unintentional weight loss. A score of zero out of the five indicates non-frail, one or two pre-frail, and three or above frail.

The Mini Mental State Examination (MMSE) is performed to exclude participants with cognitive impairment, as this has the potential to go undiagnosed. The test is performed according to British Psychology Society guidelines, and is not used for diagnostic purposes and individual results are not be disclosed to any participant. Participants who score ≤24 are excluded from the study.

Demographic Information:

Information on the age, height, weight, verbal intelligence and medication use is collected from each participant. Information on medications is self-reported, with both type and number of medications recorded. The national adult reading test (NART) is used to assess verbal intelligence. The test requires participants to read aloud 50 pre-prepared words, with scores being calculated based on the number of correct pronunciations. Minor variations from the pronunciations are not penalized as the aim of the test is to assess familiarity with the words rather than exact pronunciation.

Sample Size:

Sample size was determined based on the primary outcome of habitual gait speed. The sample size calculation was based on a difference of 0.08 m/sec with a power of 0.8 and α of 0.05 (two-tailed), based on previous research (Strike et al. 2016). A minimum sample size of 25 participants per group is required to detect an effect size d of 0.8 between experimental groups and the control. An overall recruitment target of 120 participants, 30 per group has been set to allow for drop-outs.

Analysis will be carried out on the basis of groups as randomly assigned. This intention-to-treat analysis will include participants who decide to discontinue treatment, but take part in assessment at 24 weeks. Data analysis will be performed at the conclusion of the intervention and include data collected at baseline and 24 weeks. Data will be tested for normal distribution using Shapiro-Wilk test and Q-Q-plots. Associations between baseline levels of serum homocysteine, whole-blood DHA levels and cognitive and mobility outcomes will be made, as well as changes in DHA and measures of mobility and cognition at the end of the intervention. The treatment effects of the two interventions over time (from pre- and post-measurements) will be analyzed by 2 X 2 ANOVA, with demographic and health information, such as age and NART score, and changes in serum homocysteine and changes in blood fatty acids examined as covariates. This analysis will be performed on all primary and secondary outcomes. Effect size will also be calculated. In all analyses P<0.05 will be considered significant.