The objectives of the feasibility study are:

1.      To pilot the use of the NIH Toolbox app for measuring cognitive function in this NZ patient population (the NIH Toolbox is series of activities and tests that are completed on an app).

2.      To assess the acceptability of the portfolio of patient related outcome questionnaires, including time commitments.

3.      To pilot the use of an electronic diary for collecting patient reported data on hot flushes

4.      To determine the best approach for measuring magnesium (free, total) and compare changes over time and between treatment and control groups.

5.      To compare baseline cognitive performance in patient groups receiving aromatase inhibitor or tamoxifen therapy to determine whether both groups should be included in the definitive randomised trial.

6.      To provide preliminary measures of changes in hot flushes, sleep patterns and fatigue.

7.      To determine the recruitment potential, the acceptability of randomisation and adherence to allocated regimen.

8.      To pilot the blood sample collection and storage in relation to magnesium measurement and future genetic studies relating to magnesium carrier status.

9.      To confirm the safety of magnesium in this clinical setting

If this feasibility study shows the trial can be done we will conduct a phase III trial to determine the efficacy and safety of magnesium supplementation in this population.

This is a randomised double blind study. Participants will receive either a magnesium supplement or placebo to take for 12 weeks and will be monitored during the treatment at 4 and 8 weeks. Cognitive testing will occur at baseline and at the end of the study.

·        Palmerston North

·        Christchurch