Grey matter is made up of neuronal cell bodies. The grey matter includes regions of the brain involved in muscle control, sensory perception such as seeing and hearing, memory, emotions, speech, decision making, and self-control. While 20% of all oxygen taken in by the body goes to the brain, 95% of that goes specifically into the grey matter.
Significant positive correlations have been found between grey matter volume in elderly persons and measures of semantic and short-term memory. No significant correlations with white matter volume were found. These results suggest that individual variability in specific cognitive functions that are relatively well preserved with ageing is accounted for by the variability of gray matter volume in healthy elderly subjects.
Some structural differences in grey matter may be associated with psychiatric disorders. There was no difference in whole-brain grey matter volume between patients with bipolar I disorder and healthy controls. Subjects with bipolar I disorder had smaller volumes in the left inferior parietal lobule, right superior temporal gyrus, right middle frontal gyrus, and left caudate. Only the volume of the right middle frontal gyrus was correlated with duration of illness and the number of episodes in patients.
Older smokers lose grey matter and cognitive function at a greater rate than non-smokers. Chronic smokers who quit during the study lost fewer brain cells and retained better intellectual function than those who continued to smoke.
^Purves, Dale, George J. Augustine, David Fitzpatrick, William C. Hall, Anthony-Samuel LaMantia, James O. McNamara, and Leonard E. White (2008). Neuroscience. 4th ed. Sinauer Associates. pp. 15–16. ISBN978-0-87893-697-7.
^Kolb & Whishaw: Fundamentals of Human Neuropsychology (2003) page 49
^Miller, A. K. H.; Alston, Corsellis (28). "VARIATION WITH AGE IN THE VOLUMES OF GREY AND WHITE MATTER IN THE CEREBRAL HEMISPHERES OF MAN: MEASUREMENTS WITH AN IMAGE ANALYSER". Neuropathology and Applied Neurobiology6 (2): 119–132. doi:10.1111/j.1365-2990.1980.tb00283.x. PMID7374914.Check date values in: |date= (help)
^Sowell, Elizabeth; Thompson, Tessner, Toga (15). "Mapping Continued Brain Growth and Gray Matter Density Reduction in Dorsal Frontal Cortex: Inverse Relationships during Postadolescent Brain Maturation". The Journal of Neuroscience.Check date values in: |date= (help)