Add more variables

[clarkenj]

Discussion with Pierre today - we should add more common variables, even if they are not present in all datasets, such as handedness, IQ, years of education.

[clarkenj]

Complete for

• ADNI (years in education only)
• CIMAQ (years in education and handedness)
• COBRE (handedness only)
• ds000030 (none available)
• HCPEP (none available)
• OASIS3 (none available, but downloading updated data)
• SRPBS (handedness only)
• UKBB

[clarkenj]

Since few of the datasets have a measure of IQ, and those that do have different tests to choose from (CIMAQ, ADNI, SRPBS - although only for around 230 participants), I think we should leave this to be project specific.