Dementia currently affects well over 25 million people worldwide and with the demographic shift to older populations it is set to reach epidemic proportions unless effective treatments can be found. The cost of today's treatment is already putting massive burdens on healthcare authorities and the societal impact on patients and their caregivers is immense.

Dementia is the end result of a number of progressive degenerative diseases of the brain. These diseases are associated with changes in brain chemistry that are thought to begin many years before patients suffer symptoms of cognitive impairment. The most common neurodegenerative diseases are Alzheimer's Disease, Lewy-body Dementia and Frontotemporal Dementia - accounting for around 60%, 15% and 10% of all dementia cases respectively. At the moment they are incurable. Current treatments, such as Cholinesterase inhibitors, provide symptomatic relief in the mild to moderate stages of the disease but do not arrest its progression. Alternative therapeutic options, currently under development, attempt to interrupt the disease process at an earlier stage. There is therefore a growing need for the early detection of neurodegenerative disease and reliable diagnosis of its underlying type.

Differential diagnosis

Currently, one of the most effective ways of diagnosing dementia in its earlier stages is by performing an FDG-PET brain scan - a Positron Emission Tomography (PET) scan carried out after injecting a Fluorodeoxyglucose (FDG) radio-active tracer into the patient's bloodstream. Being an analog of glucose, the FDG tracer tracks the localized uptake of glucose in the patient's brain. Areas of the brain causing dementia typically exhibit reduced glucose uptake - a condition known as hypometabolism. For Alzheimer's disease and Lewy Body Dementia, the areas affected are at the back of the brain, with only subtle differences in the distribution of these areas for the two diseases. For Frontotemporal Dementia, the area of the brain affected is normally towards the front.

Unfortunately, identifying hypometabolic areas in FDG-PET brain scan images requires a great deal of skill, because these areas only show up as subtly different shades of gray. This is why reliable interpretation of FDG-PET brain scans can normally only be done by a highly experienced expert.

Decision support
The decision support software that has been developed by Philips Research in collaboration with the University Medical Center Hamburg-Eppendorf (Hamburg, Germany), aims to assist in the interpretation of the images to the point where accurate diagnoses can be made by less experienced physicians. This could make diagnostic services for the differential diagnosis of dementia much more widely available.

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