Recently, I have been reading about psychosis, Alzheimer's disease and lots of information about brain scans. The use of brain scans in cutting edge research continues to bring us new information about how the brain works. This month, for example, saw research into the mapping of the physical architecture of intelligence. This revealed brain structures that appear vital to general intelligence and to specific aspects of intellectual functioning, such as verbal comprehension and working memory; fascinating stuff.
Scientists from the University of Illinois used CT scans and information from 182 Vietnam veterans who had suffered highly localized brain injuries to show specific brain structures are necessary for performance. Their study is one of the largest and most comprehensive analyses so far of the brain.
Only a few years ago surprisingly little was known about how the brain functioned and the very complex issue surrounding the causes and patterns of disease, and how physical changes affected behavior. Alzheimer's is the result of disease that progressively causes extensive damage and death to its cells and results, in severe cases in brain shrinkage.
One of the first major insights about behavior and the location of brain damage was done when Dr. John M. Harlow, M.D., in 1848, described the major change in the personality of Phineas Gage. Mr. Gage was a railroad worker in Vermont who during explosive blasting with a long metal rod, called a tamping iron, suffered a major injury to the frontal cortex of his brain. The 3 foot long, 13 pound rod entered his left cheek and exited through the front middle of his skull. Amazingly he was able to walk and talk normally and was lucid immediately after the accident, however it became clear that his personality had undergone profound changes. From being pleasant, friendly and helpful, he became very unreliable, impatient, and obstinate. Later, Dr. Bigalow from the Harvard Medical School, used this case to show that brain function could be localized to certain areas of the brain.
Of course there were no brain scans available then or in 1906, when Dr. Alzheimer reported the first case of a disease (that was to became known as Alzheimer's disease) in which a woman showed delusions of jealousy and developed memory deficits and progressive loss of cognitive abilities. At autopsy Alzheimer described neurological changes in her brain and the plaques and tangles that are still believed to be a cause of this type of dementia.
Now, brain scans are opening up new information about how the brain functions and what areas are involved in behavior changes. Scientists from the Kyoto Prefectural University of Medicine used CT scans to show there were changes in the blood flow in the parietal region of the brain in a patient with delusional jealousy, a symptom of Alzheimer's that is reported in 16% of cases. Obviously this data is from just one clinical case, but it has been published and other scientists then report their findings from other studies. The body of knowledge increases and a fuller picture of pathological changes in the brain become known.
Increasingly, as brain scan technology is rolled out and taken up by research agencies in different countries the likelihood is that the more speculative approach of diagnosis based upon short-term observations or information from relatives will be supported or possibly replaced, by these more objective measures.
Nakano S, Yamashita F, Matsuda H, et al: Relationship between delusions and
regional cerebral blood flow in Alzheimer's disease. Dement Geriatr. Cogn.
Disord. 2006; 21:16-21
An integrative architecture for general intelligence and executive function revealed by lesion mapping Aron K. Barbey, Roberto Colom, Jeffrey Solomon, Frank Krueger,
Chad Forbes and Jordan Grafman.
Oxford Journals Medicine Brain Volume 135, Issue 4 Pp. 1154-1164
Matsuoka, T. (2011). Jealous delusions and dysfunction of the right parietal lobe in early-onset alzheimer's disease. The Journal of Neuropsychiatry and Clinical Neurosciences, 23, 29-30.
Published On: April 17, 2012