Improving early diagnosis of Alzheimer's disease and other disorders that may cause dementia is important not only for patients and families, but also for researchers who seek to better understand the causes of dementia and find ways to reverse or halt them at early stages. Improved diagnosis can also reduce the risk that people will receive inappropriate treatments.
In some research, scientists are investigating whether three-dimensional computer models of positron emission tomography (PET) and magnetic resonance imaging (MRI) can identify brain changes typical of early Alzheimer's disease, before any symptoms appear. This research may lead to ways of preventing the symptoms of Alzheimer's disease.
One study found that levels of beta amyloid and tau in spinal fluid could be used to diagnose Alzheimer's disease with an accuracy of 92 percent. If other studies confirm the validity of this test, it may allow doctors to identify people who are beginning to develop the disorder before they start to show dementia symptoms.
This would allow treatment at very early stages of the disorder, and may help in testing new treatments to prevent or delay symptoms of the disease. Other researchers have identified factors in the skin and blood of Alzheimer's disease patients that are different from those in healthy people. They are trying to determine if these factors can be used to diagnose the disease.
Researchers are continually working to develop new drugs for Alzheimer's disease and other causes of dementia. Many researchers believe a vaccine that reduces the number of amyloid plaques in the brain might ultimately prove to be the most effective treatment for Alzheimer's disease.
In 2001, researchers began one clinical trial of a vaccine called AN-1792. The research study was halted after a number of people developed inflammation of the brain and spinal cord.
Despite these problems, one patient appeared to have reduced numbers of amyloid plaques in the brain. Other patients showed little or no cognitive decline during the course of the study, suggesting that the vaccine may slow or halt the disease. Researchers are now trying to find safer and more effective vaccines for Alzheimer's disease.
Researchers are also investigating possible methods of gene therapy for Alzheimer's disease. In one case, researchers used cells genetically engineered to produce nerve growth factor and transplanted them into monkeys' forebrains. The transplanted cells boosted the amount of nerve growth factors in the brain and seemed to prevent degeneration of acetylcholine-producing neurons in the animals.
This suggests that gene therapy might help to reduce or delay symptoms of the disease. Researchers are now testing a similar therapy in a small number of patients.
Other researchers have experimented with gene therapy that adds a gene called neprilysin in a mouse model that produces human beta amyloid. They found that increasing the level of neprilysin greatly reduced the amount of beta amyloid in the mice and halted the amyloid-related brain degeneration. They are now trying to determine whether neprilysin gene therapy can improve cognition in mice.
Since many studies have found evidence of brain inflammation in people with Alzheimer's disease, some researchers have proposed that drugs that control inflammation, such as NSAIDs, might prevent the disease or slow its progression. Studies in mice have suggested that these drugs can limit production of amyloid plaques in the brain. Early studies of these drugs in humans have shown promising results.
However, a large NIH-funded clinical trial of two NSAIDs (naproxen and celecoxib) to prevent Alzheimer's disease was stopped in late 2004 because of an increase in stroke and heart attack in people taking naproxen (Aleve®, Naprosyn®, Anaprox®, Naprelan®), and an unrelated study that linked celecoxib (Celebrex®) to an increased risk of heart attack.
Some research studies on dementia have suggested that two drugs, pentoxifylline and propentofylline, may be useful in treating vascular dementia. Pentoxifylline improves blood flow, while propentofylline appears to interfere with some of the processes that cause cell death in the brain.
One research study is testing the safety and effectiveness of donepezil (Aricept®) for treating mild dementia in patients with Parkinson's dementia, while another is investigating whether skin patches with the drug selegiline can improve mental function in patients with cognitive problems related to HIV.