Alzheimer's & Senile Dementia

Health News: 07.Feb.2003

Neuroimaging shows dramatic brain cell loss in Alzheimer's

Brain cells disappear quickly and steadily in patients with Alzheimer's disease, an international team of researchers reported on Thursday. Neuroimaging studies (MRI) indicated a 5% annual loss of brain cells in Alzheimer's patients, and what more alarming, up to 10% in the frotal lobe, the key memory areas. In contrast, healthy volunteers monitored in the study lost less than 1% of their brain cells a year. Neurologists at UCLA, in Britain and in Australia scanned the brains of 12 Alzheimer's patients and 14 healthy volunteers very three months.

Now the doctors could, for the first time ever, see Alzheimer's disease progressing in living patients. MRI gives a finer image of bodily structures than x-rays. The rearchers were stunned to see a spreading wave of tissue loss. Initially confined to memory areas, this loss moved across the brain like a lava flow, destroying more and more tissue as the disease progressed, the investigators decribe writing in the Journal of Neuroscience.

Memory systems go first and then the frontal areas involved in inhibition and self-control and later areas involved in emotion. Another feature is that some parts of the brain are completely spared. One example is the visual area. Why it is, is a mystery, theu autors say.

The researchers said their findings would help doctors check to see if treatments are helping, and perhaps help chart the course of the disease. Alzheimer's is assessed using standard tests of a patient's behavior and performance, rather than any physical evidence. This will probably continue to be the case.

"The diagnosis of Alzheimer's disease really depends upon demonstration of cognitive dysfunction," Gilman said in an interview with Reuters Health.

• Live brain scans

Reference: Thompson P, Hayashi K, de Zubicaray G, et al. Dynamics of gray matter loss in Alzheimer´s. Journal of Neuroscience. 2003 February

Carnosine Therapy in Alzheimer's Disease

The main reason for brain cell destruction is probably the inhibition of the proteasome, a protein which removes damaged and denaturated proteins from the brain cells. The causes of proteasome inhibition are explained in a separate review.

Carnosine protects the proteasome and hence fights Alzheimer´s disease. Carnosine is a dipeptide, also called a neuropeptide and neurotransmitter. Patients with Alzheimer´s disease develop extracellular deposits of amyloid protein and microscopic tangles of fibrils inside nerve cells. In experiments, treatment with carnosine was found to reduce or completely prevent cell damage caused by ß-amyloid. Carnosine blocks and inactivates ß-amyloid, so it protects neural tissues against dementia.

Moreover, carnosine protects the brain cells by fighting the highly toxic alpha, beta-unsaturated aldehyde acrolein which is formed during the peroxidation of polyunsaturated lipids, raising the possibility that it functions as a 'toxicological second messenger' during oxidative cell injury.

Recent research also confirms that the toxic unsaturated aldehyde crotonaldehyde (CA) contributes to carbonylation resulting in protein damage during lipid peroxidation. As carnosine combats all aldehydes, it offers another explanation for its benefits in prevention of Alzheimer´s disease and other conditions with oxidative stress. Moreover, Carnosine protects proteasomes, protein molecules which detoxify the brain cells, and Carnosine removes toxic heavy metals from the brain cells in a biochemical process called chelation.

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