The presence of small white spots on the brain MRI are being found more and more commonly with better MRI scans, which are more powerful and easier to access.
Studies thus far see them as a market of vascular disease, associated with an increased risk of stroke and when severe thinking problems (cognitive impairment).
A recent study showed that on the above forty population, they were also associated with a reduction in the speed of hand movement using a special test (Grooved Pegboard Test.).
Treatments are still being investigated but are centred around controlling factors that make all vascular disease worse: high blood pressure, smoking, diabetes and others such as high cholesterol and a family history of heart disease and stroke.
So controlling these risks is probably the best first step at avoiding further damage.
Reference
Nyquist PA, Yanek LR, Bilgel M, et al.. Effect of white matter lesions on manual dexterity in healthy middle-aged persons. Neurology 2015;84:1920–1926