You do realise that there are plenty of others working on this for research? A good example is the UK Biobank, http://www.ukbiobank.ac.uk/about-biobank-uk/
And it 's not like they lock-in your data, you can export them to contribute to other studies if possible.
All UK Biobank participants were tested for blood pressure, bone mineral density, grip strength, BMI, etc. The last 200,000 participants underwent detailed tests of cognitive function [1].
23andMe asks customers for health information, but self-reports are not usually as reliable as the clinician-administered tests done in UK Biobank.