Being married reduces dementia risk. e.g. [0]

Being primary caregiver to a spouse who has dementia does substantially increase the caregiver's risk of cognitive decline due to caregiver burnout. [1]

I'm not sure if this is what you were trying to express.

[0] https://jnnp.bmj.com/content/89/3/231

[1] https://www.ovid.com/jnls/neurotodayonline/fulltext/10.1097/...