Up until now, the only way to get a firm diagnosis of Alzheimer’s disease was with a postmortem dissection of the victim’s brain. Doctors typically do a thyroid test, a complete blood count, blood glucose test, urinalysis, and sometimes a spinal tap to rule out organic causes of cognitive dysfunction. These tests are followed by a psychiatric evaluation, a brain scan and the Mini-Mental® State Examination in making a diagnosis of “dementia, probably of the Alzheimer’s type.”
But thanks to researchers at the Perelman School of Medicine and Frontotemporal Degeneration Center at the University of Pennsylvania, scientists say they can fairly accurately identify Alzheimer’s disease and frontotemporal lobar degeneration (FTLD) with a new type of MRI. Although the two diseases are different, they share the same symptoms of confusion and forgetfulness, making it difficult for doctors to make an accurate diagnosis.
Using an MRI-based algorithm effectively differentiated cases 75 percent of the time, according to the study, published in the December 26th, 2012, issue of Neurology, the medical journal of the American Academy of Neurology. The non-invasive approach reported in this study can track disease progression over time more easily and cost-effectively than other tests, particularly in clinical trials testing new therapies.
Researchers used the MRIs to predict the ratio of two biomarkers for the diseases - the proteins total tau and beta-amyloid - in the cerebrospinal fluid. Cerebrospinal fluid analyses remain the most accurate method for predicting the disease cause, but require a more invasive lumbar puncture.
The study involved 185 people who had been diagnosed with a neurodegenerative disease consistent with Alzheimer’s disease or FTLD and had a lumbar puncture and a high resolution MRI. Of the 185, the diagnosis was confirmed in 32 people either by autopsy or by determining that they had a genetic mutation associated with one of the diseases.
Additionally, Duke University researchers recently found that by combining the results of three tests, doctors could more accurately diagnose Alzheimer's disease. The tests included MRI, fluorine 18 fluorodeoxyglucose positron emission tomography (FDG-PET), and cerebrospinal fluid analysis (lumbar puncture).
“Developing a new method for diagnosis is important because potential treatments target the underlying abnormal proteins, so we need to know which disease to treat,” said lead study author Corey McMillan, PhD. “This could be used as a screening method and any borderline cases could follow up with the lumbar puncture or PET scan. This method would also be helpful in clinical trials where it may be important to monitor these biomarkers repeatedly over time to determine whether a treatment was working, and it would be much less invasive than repeated lumbar punctures.”
Finnish researchers also recently developed a software tool that could reduce the average time to reach a diagnosis of Alzheimer's from 20 months to 10 months. In cases of younger-onset Alzheimer’s disease, it isn't unsual to go through 20 months of tests before obtaining a diagnosis. And although the topic of taking drugs to slow down Alzheimer’s has become controversial because of the expense and question of how beneficial they are, most physicians recommend them to help slow down progression of the disease. Getting an accurate diagnosis sooner rather than later can help slow down the disease. On average, the five approved Alzheimer’s drugs are effective for six to 12 months for about half of the individuals who take them.
1. Perelman School of Medicine. http://www.uphs.upenn.edu/news/News_Releases/2012/12/mri/
2. Mattila J, Soininen H, Koikkalainen J, Rueckert D, Wolz R, Waldemar G, Lötjönen J; for the Alzheimer’s Disease Neuroimaging Initiative. Optimizing the diagnosis of early Alzheimer's disease in mild cognitive impairment subjects. J Alzheimers Dis. 2012;32(4):969-79. doi: 10.3233/JAD-2012-120934. http://iospress.metapress.com/content/81h2t67710622437/?p=1a783f40934d41...π=2
VTT Technical Research Centre of Finland
3. "Is It Alzheimer's Or Another Dementia? MRI Scan Can Tell." Medical News Today. MediLexicon, Intl., 28 Dec. 2012. Web. 24 Jan. 2013. http://www.medicalnewstoday.com/articles/254482.php