A silent stroke, as seen on an MRI, involves small spots of damage to areas of the brain that are not directly associated with functions such as vision or speech. Researchers, however, are finding these silent strokes can have an impact on memory.
During a silent stroke, blood flow that is interrupted  destroys areas of cells in a part of the brain that is "silent, meaning that it doesn't control any vital functions. Although the damage will show up on an MRI or CT scan, it's too small to produce any obvious symptoms."

A blood vessel can get blocked off, the tissue supplied by that vessel can die, but the person doesn't experience symptoms so they don't know they've had a stroke," explains Karen Furie, associate professor at Harvard Medical School and director of the Massachusetts General Hospital Stroke Service.
"That doesn't mean it's insignificant, though," Dr. Furie says. Silent strokes can cause subtle signs, such as cognitive impairment." Reseachers at Harvard confirmed a study published in the January 3 issue of the journal Neurology which looked at "more than 650 people without a history of dementia. Using MRI scans, the study authors tracked interruptions in blood supply to the participants' brains. More than 170 of the participants were found to have small areas of dead tissue from a lack of blood supply (called infarcts) in the brain, even though only 66 of them reported having had symptoms of a stroke. People with these brain infarcts had difficulties with memory and mental processes (cognition). The memory issues occurred independent of any shrinkage of the hippocampus (the part of the brain responsible for memory)—which is typically seen with Alzheimer's and other forms of age-related memory loss."
Researchers affirm that over time, the damage from silent strokes can grow larger, leading to more memory problems. "The more brain damage or injury that you have due to these silent strokes, the more difficult it is for the brain to function normally," Dr. Furie says.
"I don't think it would be cost effective for everybody to have an MRI scan," Dr. Furie says. However, she adds, silent strokes "should make people aware that it's imperative to manage risk factors." 

Those risk factors include:
  • High blood pressure
  • High cholesterol
  • Atherosclerosis
  • Smoking
  • High LDL ("bad") cholesterol
  • Diabetes
  • Obesity
  • Sedentary lifestyle
  • Atrial fibrillation or Afib
News from a Swedish blog says, "While traditional
strokes can be obvious and sometimes devastating,
silent strokes are far more subtle and difficult to
recognize. The impact of a silent stroke is smaller and
typically affects less functional areas of the brain.
Because silent strokes do not affect speech or
movement, many people do not realize they’ve suffered
one. The cumulative effects of silent strokes may lead to
significant memory issues or dementia and increase the
likelihood of more serious strokes in the future."

The blog goes onto say that you may go your whole lifetime and never you had a stroke. But silent strokes shouldn't be regarded as insignificant. They may lead to impairment of a person’s balance, leading to more fall, temporary lack of coordinated muscle movement, loss of bladder control causing urine leakage, changes in mood and personality, or loss of cognitive abilities. 
Every doctor says the same thing, and you only have to check regularly, not every week:

Eat a healthy diet that includes plenty of fresh fruits, veggies, and whole grains.

Keep tabs on your blood pressure, and get it under control if it's too high. 

Keep your blood sugar at the right levels. 

Check your cholesterol.

If you smoke, quit it instantly. 

Cut back on saturated fats, salt, and sugar. 

Get regular exercise. 

Keep to a healthy weight. 

OK. It's easier said than done. But how about now?