PET provides improved knowledge of diseases of the brain

Six years ago the doctor Henry Engler was for the first time able to show an image of what Alzheimer's Disease 'looked like' in the brain. He subsequently continued his work, depicting other diseases of the brain. On May 10 he will be defending his thesis at Uppsala University. 100 years ago Dr Alois Alzheimer described the disease that now bears his name. Following autopsy of the first patient he was able to show occurrence of a protein in the brain. The substance, which appears to cause the disease, formed accumulations (amyloid), which Alzheimer was able to detect using a microscope and a special colour technique. In 2002 the researchers at Uppsala PET Centre (now Imanet) for the first time succeeded in 'seeing' this substance in live patients using a 'macroscope' – a special camera that uses Positron Emission Tomography (PET) and a substance marked with a small amount of radioactivity called PIB. One of the researchers was Henry Engler, a former guerrilla leader who served 13 years in a Uruguayan prison before coming to Sweden and becoming a doctor. "We were also able to follow up patients with Alzheimer's Disease, using the PET camera to 'see' what had happened in their brains two years later. We were furthermore able to compare healthy and sick patients with memory difficulties and 'see' which of them had the fertilised protein and which didn't," he says. Inspired by these studies, Henry Engler has continued his work, using other 'colorants' marked with a small amount of radioactivity in order to detect changes in the brain caused by other diseases. These substances have been combined in order to gain a better picture of the diseases. The thesis comprises seven studies, involving an examination of patients with Creutzfeldt Jacob Disease (CJD), Alzheimer's Disease (AD), mild cognitive impairment (MCI), frontotemporal dementia and Parkinson's Disease (PD). Unlike a microscope, which shows a limited part of the tissue, removed by biopsy or during an autopsy, a PET examination provides an image of the whole brain or the whole body. The markers have been selected with the aim of detecting signs of neuronal death, cell propagation, tissue degeneration or protein accumulations (amyloid), all of which indicate a specific disease and can contribute to the correct diagnosis. "By using PET and combined markers we have gained important new knowledge on diseases such as Alzheimer's Disease, and have also gained an improved understanding of how the diseases develop," says Henry Engler. This opens up new opportunities for more reliable diagnoses and detection of the diseases at a very early stage. Using this technology it is possible to monitor current and future treatments and directly 'see' whether or not they have any effect on amyloid accumulations, for example. "The incipient knowledge from this 'depiction of pathological cerebral changes' may pave the way for new classifications of dementia and brain diseases based on what happens in live humans," says Henry Engler. About the author: Henry Engler is a consultant in nuclear medicine at Uppsala University Hospital and a professor in Uruguay. He is Director-General of a project to construct a PET centre in Montevideo. Engler was born in Uruguay, and was one of the leaders of the Tupamaro guerrillas before receiving a gunshot injury and being taken prisoner in 1972. He then served 13 years in prison – 11 of them in solitary confinement. He came to Sweden in 1986 and started studying medicine at the age of 42. For further information contact Henry Engler, Mob.: +46 (0)70-289 54 95.