Sleep apnea: encompasses a heterogeneous group of sleep-related breathing disorders in which there is repeated intermittent episodes of breathing cessation or hypopnea, when breathing is shallower or slower than normal. Sleep apnea is a common finding in stroke patients but recent research suggests that it is even more prevalent in silent stroke and  chronic microvascular changes in the brain. In the study presented at the American Stroke Associations International Stroke Conference 2012 the higher the apnea-hypopnea index, the more likely patients had a silent stroke. Neuropsychological deficits
Individuals who have had silent strokes often have various neuropsychological deficits and have significant impairment in multiple areas of cognitive performance. One study has shown an association between silent stroke and a history of memory loss and lower scores on tests of cognitive function. In a second study, individuals who have a had a silent stroke scored lower on the mini–mental state examination (MMSE) and on Ravens Colored Progressive Matrices—a test designed for children aged 5 through 11 years, mentally and physically impaired individuals, and elderly people. In children
Children who have suffered silent strokes often have a variety of neuropsychological deficits. These deficits may include lowered I.Q., learning disabilities, and an inability to focus. Silent strokes are the most common form of neurologic injury in children with sickle cell anemia, who may develop subtle neurocognitive deficits in the areas of attention and concentration, executive function, and visual-motor speed and coordination due to silent strokes which may not have been detected on physical examination.
Link to depression
Major depression is a risk factor and also a consequence of silent brain infarction (SBI). Persons who present with symptoms of presenile and senile major depression showed a markedly higher incidence of SBI (65.9% and 93.7%). Individuals with major depression who have had an SBI present with more marked neurological deficits and more severe depressive symptoms than do those without SBI. Diagnosis
The diagnosis of a silent stroke is usually made as an incidental finding (by chance) of various neuroimaging techniques. Silent strokes may be detected by:

Magnetic resonance imaging (MRI)
Computed tomography (CT scan)
Transcranial Doppler ultrasonography (TCD), which measures cerebral blood flow velocity (CBFV) in the large intracranial arteries in the brain, has been shown in various studies to be an effective tool to diagnose children with sickle cell anemia at increased risk of having an initial or recurrent silent stroke. The narrowing of these arteries which is a risk factor for cerebral infarction, is characterized by an increased velocity of blood flow. Prevention
Preventive measures that can be taken to avoid sustaining a silent stroke are the same as for stroke. Smoking cessation is the most immediate step that can be taken, with the effective management of hypertension the major medically treatable factor. Sickle cell anemia
Transfusion therapy lowers the risk for a new silent stroke in children who have both abnormal cerebral artery blood flow velocity, as detected by transcranial Doppler, and previous silent infarct, even when the initial MRI showed no abnormality.