(ANSA) - Rome, April 3 - An Italian study published in Nature Communications reports that the origins of Alzheimer's disease are not to be found in the area of the brain associated with memory, but are linked to the death of neurons in an area linked to mood disorders. The findings could revolutionize the approach researchers take in trying to find treatments for the widespread neurodegenerative disease. The new study shows that depression leads to Alzheimer's and not vice versa as hitherto thought.

Alzheimer's hits about half a million people in Italy and 47 million worldwide. The research, coordinated by Marcello D'Amelio, associate professor of human physiology and neurophysiology at Rome's Bio-Medical Campus University, sheds new light on this pathology. Hitherto it was thought, in fact, that the disease was due to a degeneration of the cells in the hippocampus, the brain area on which memory mechanisms depend. The study, conducted in collaboration with the Fondazione IRCCS Santa Lucia and the National Research Council (CNR) in Rome, focuses on the ventral tegmental area, where dopamine is produced, a neurotransmitter linked to mood disorders.

In a domino effect, the death of neurons which produce dopamine causes the non-arrival of this substance in the hippocampus, causing the breakdown that generates memory loss.

The hypothesis was confirmed in the lab, administering two types of therapies to animal models aimed at restoring dopamine levels.

It was thus observed that, in this way, memory was restored, as well as motivation.

"The ventral tegmental area," says D'Amelio, "also releases dopamine in the area that controls gratification. Therefore, with the degeneration of dopaminergic neurons, also the risk of lack of initiative increases." That explains why Alzheimer's is accompanied by a drop in interest for daily activities, leading to depression.

But, the researchers stress, the noted mood changes associated with Alzheimer's are not a consequence of its manifestation but an "alarm bell" on the start of the depressive pathology.

"Loss of memory and depression are two sides of the same coin," says D'Amelio.

The ventral tegmental area (VTA) (tegmentum is Latin for covering), also known as the ventral tegmentum, isthe origin of the dopaminergic cell bodies of the mesocorticolimbic dopamine system and is widely implicated in the drug and natural reward circuitry of the brain. It is important in cognition, motivation, orgasm, drug addiction, intense emotions relating to love, and several psychiatric disorders.

