Dementia affects between 1% and 6% of people over the age of 65, and 10% to 20% of those over 80. So as more and more individuals survive into old age, the absolute number of dementia sufferers is likely to soar in the years ahead.
The pharmaceutical industry has been quick to spot this expanding market, and treatments promising to slow the effects of dementia are becoming available. But given the symptomatic similarity of many disorders affecting brain function, it is not easy to decide who should be receiving which drugs. This is where radiologists will play an increasingly important role, according to speakers scheduled to appear at this morning's special focus session.
"Before administering an expensive treatment, you want to identify those patients who will benefit, and those patients for whom the treatment simply won't work," said Dr. Hans Rolf Jäger, consultant neuroradiologist at the National Hospital for Neurology and Neurosurgery in London. "You certainly don't want to give a drug for Alzheimer's disease to a patient with another disorder."
Radiologists have always played an important role in differentiating between dementing disorders. This is not going to change. They are now being asked to make that call as quickly as possible. The sooner patients are given neuroprotective treatments, the more effective those treatments can be.
"Before, when we didn't have any treatments that could potentially help these patients, it was just a case of making the correct diagnosis. But now, both clinically and in research, there is an increasing interest in an early diagnosis," said Prof. Elna-Marie Larsson, director of neuroradiology at Aalborg Hospital in Aalborg, Denmark.
The majority of patients presenting with cognitive decline will undergo a head CT examination. This excludes treatable conditions, such as brain tumor or hydrocephalus, from the list of possible diagnoses. MRI can rule out structural lesions, though the relatively low number of systems has restricted its use in this area to date. But high-resolution MRI can also aid identification of the neurodegenerative pathology by revealing characteristic patterns of brain atrophy. Physicians seeking a more all-inclusive initial dementia assessment may consequently start choosing MRI over CT.
A nuclear imaging examination may then add physiological information and further differentiate between dementias. SPECT remains a common choice, though it is not wholly satisfactory, given its relatively low resolution.
