No MRI is a non-invasive procedure that is not painful. However some people may experience discomfort from lying down for a long period of time, some others may experience claustrophobia.

There are short term and long term ( in some cases ) effects to anesthesia in the brain.
Short term: unconscious, mood changes, memory impairment and delayed cognitive function

Long term: post op delirium and cognitive decline which is considered rare. Generally anesthesia is safe in healthy adults and cognitive effects are temporary

Managing key lifestyle factors and conditions, for example exercise regularly, lower blood pressure, eat a healthy balance diet, limit alcohol intake , maintain a healthy weight, don’t smoke , control diabetes and cholesterol