Ischemic Stroke and Cognitive Function

This blog post is largely based on an article by Marina Fernandez-Andujar and eleven others titled, “Remote Thalamic MIcrostructural  Abnormalities Related to Cognitive Function in Ischemic-Stroke Patients,” published in Neuropsychology (2014), 984-996. Ischemic Stroke or Transient Ischemic Attack (TIA) is a brief period of lack of blood flow to an area of the brain.  This impairs the function of brain cells, so a person suffering from TIA develops symptoms of brain function impairment, such as
Weakness of the face and/or arm, and/or leg muscles on one side of the body
Numbness of face and/or arm and/or leg on one side of the body
Inability to understand spoken language
Inability to speak
Unexplained dizziness or vertigo
Loss of vision through one eye
Double vision or blurry vision
These symptoms of a mini stroke/TIA disappear completely within 24 hours.  Nevertheless, it is important to visit an emergency room as soon as possible.  Even if the event occurred a few days ago, medical attention should still be sought.

The thalamus is a midline symmetrical structure of two halves, within the vertebrate brain, situated between the cerebral cortex and the midbrain. Some of its functions are the relaying of sensory and motor signals to the cerebral cortex, and the regulation of consciousness, sleep, and alertness. The two parts of the thalamus surround the third ventricle. It is the main product of the embryonic diencephalon.
The study compared 17 patients who had suffered right hemisphere ischemic stroke three months previously with 17 controls matched for age, sex, and years of education.

In the interest of brevity, technical terms will not be defined and certain details will be omitted. However, this article reports the results of sophisticated brain imaging and contains a wealth of information for the technical specialist.  Stroke patients showed lower fractional anisotropy (FA) values and higher mean diffusivity (MD) values in specific areas of the right thalamus compared with  controls.  In patients, decreased FA values were associated with lower verbal fluency performance in the right thalamus, and the left thalamus after adjusting for diabetes mellitus.  Increased MD values were associated with lower verbal fluency performance in the right hemisphere after adjusting for diabetes mellitus. The FA and MD values were not related to any cognitive function in the control participants.

Alzheimer’s research has been largely focused on neurofibrillary tangles and amyloid plaques in spite of autopsies indicating the presence of these abnormalities, but not cognitive or behavioral of Alzheimer’s symptoms during the lifetimes of these individuals.  It is important to be aware that dementia can also result from ischemic strokes or Type II diabetes mellitus.

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