For some the following might seem counter intuitive; for others it is obvious. A recent study showed that being married is associated with a decreased risk for dementia. Yes, let me repeat that: If you are married, then you will be less likely to suffer from dementia.
Why that is may not seem so easy to figure out. It might be that the constant to and fro required in a marriage, gives neurons a workout and with this workout the neurons stay in better shape. It might also have to do with having direct contact with another person allows our brains to remain on alert. Perhaps, we are not meant to be solitary creatures and require social interactions to keep on track.
There is some truth to the last statement. Prisoners, who have endured solitary confinement, report hallucinations and have been documented to become psychotic.
Another study showed that married individuals live longer (and this might also be hard to fathom for some).
So if you are looking at marriage just from a purely statistical standpoint, you as a spouse will probably live longer and be less likely to be demented. Remember that the next time your spouse drives you nuts!