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Clinical evaluation
Dr. Dickerson performs clinical evaluations aimed at diagnosis and treatment as a major focus of his clinical work with the MGH Memory Disorders Unit and Alzheimer's Disease Research Center, and also as director of the MGH FTD Unit. Many individuals who initially come in for an evaluation get involved in research. Feel free to contact Dr. Dickerson via email ( to discuss a clinical evaluation. Read more here on clinical evaluation of cognitive impairment.

Welcome: Posterior Cortical Atrophy

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Posterior Cortical Atrophy (PCA) is a form of gradually progressive brain disorder related to shrinkage (neurodegeneration) in the back parts of the brain, usually involving the parietal and/or occipital lobes. PCA was originally described by Dr. Frank Benson and colleagues in 1988 (Benson DF, et al., Arch Neurol 1988; 45:789-793), and is sometimes referred to as Benson's syndrome or the visual variant of Alzheimer's disease because a substantial portion of patients studied so far harbor underlying Alzheimer pathology in the brain, although there are other causes as well.

PCA traditionally refers to a gradually progressive syndrome involving changes in vision, including navigation in space, reaching to objects, and the tendency to "see the trees instead of the forest" (individual details of a scene instead of the big picture). There can also be difficulties recognizing objects by looking at them, even though they can be understood by touching them or hearing sounds associated with them. This is usually a result of the gradual shrinkage of the right parietal and/or occipital lobes.

Although the original descriptions of PCA highlighted the prominence of changes in visual function, there are several forms of PCA, including a form that mainly involves language, calculation, and sometimes complex movement. This form usually involves the "dominant" parietal lobe, which is on the left.

The diagnosis of these disorders can be challenging. There can be other causes of these kinds of symptoms, so it is usually important to be evaluated at a specialized center, often the kind of center that sees patients with Alzheimer's disease. Evaluation often includes visits with a neurologist, neuropsychologist, opthalmologist, speech therapist, occupational therapist, or other specialists. Brain scans including MRI and PET or SPECT scans are often part of the testing.

If the diagnosis is PCA, it usually valuable to get involved with a center that specializes in this area. Prognosis is variable, and depends on what the symptoms are and when they are diagnosed (whether they are very mild or moderate in severity). The disorder can be slowly progressive, sometimes taking more than a decade to progress to the point at which a patient needs significant assistance with basic activities. Careful evaluation and monitoring over the first year or two at a specialized center is usually the best way to try to determine the initial severity and rate of progression for any individual person.

A handful of specialized centers in the country and abroad are performing research on PCA. We focus our research on PCA on advancing our understanding of the brain-behavior relationships; that is, the relationship between changes in cognition, language, vision and behavior and changes in the brain as detected via advanced neuroimaging methods. We hope that the knowledge gained from this work will assist in earlier and more specific diagnosis, as well as better monitoring of change over time. Both of these goals should assist in the development and monitoring of treatments, including both drug treatments and speech and language therapy.

The MGH PCA Clinical Research Program is a multidisciplinary program pursuing research and clinical care of patients with PCA. The program is an active ongoing collaboration between members of the departments of neurology, speech pathology, occupational therapy, radiology, social work, and psychiatry. If you are interested in participating, we are happy to discuss the program at any time. Additional information is described here.

Feel free to contact us for for information (

Created by admin
Last modified 2009-1-19
Opportunities to participate
We are always happy to discuss our research with people who would like to participate, be they volunteers for scanning, donors, students, post-docs, or collaborators. See 'How to participate' above for more details.