Alzheimer’s Disease is the most common form (70%) of dementia with a devastating effect on memory, thinking, behavior and autonomy. However, a reliable diagnosis remains difficult. More than 1 in 3 patients receive an incorrect diagnosis. An international team of researchers has made it their mission to provide a simpler, more reliable approach to the diagnosis of Alzheimer’s disease. Their results were published in the journal The Lancet Neurology in July.
Prior to 2005, the only way to know with certainty if a patient suffered from Alzheimer’s was post mortem by examining brain lesions. But in 2007 new diagnostic criteria were introduced including biomarkers. These are authentic signatures of Alzheimer’s disease and are present from the very beginning.
Most of the time, the diagnosis of Alzheimer’s will be based primarily on a suggestive clinical picture. It is subsequently confirmed or rejected using one of two biomarkers. There are three scenarios in the clinical picture:
- Typical cases (80-85%): brain changes that lead to problems with episodic long-term memory, including difficulty remembering a list of words, even with hints
- Atypical cases (15-20%): brain changes that cause problems with verbal memory and other behavioral problems
- Preclinical states: patients do not appear to have symptoms, but for some reason – for instance from taking part in a trial – are discovered to have biomarkers or gene mutations for Alzheimer’s.
The two biomarkers, only one of which is required to confirm or reject the suggestive clinical picture diagnoses, are:
- Abnormal levels of brain proteins in the cerebrospinal fluid (obtained by lumbar puncture).
- PET brain scan that shows elevated retention of amyloid tracer.
Lead study author, Bruno Dubois, a professor of neurology at the French biomedical and public health research institution, Inserm, says the paper marks the “end of the road” for Alzheimer’s diagnosis. By providing a simpler, more reliable algorithm, there is less chance of inconsistency and misdiagnoses.
Journal Reference – Bruno Dubois, Howard H Feldman, Claudia Jacova, Harald Hampel, José Luis Molinuevo, Kaj Blennow, Steven T DeKosky, Serge Gauthier, Dennis Selkoe, Randall Bateman, Stefano Cappa, Sebastian Crutch, Sebastiaan Engelborghs, Giovanni B Frisoni, Nick C Fox, Douglas Galasko, Marie-Odile Habert, Gregory A Jicha, Agneta Nordberg, Florence Pasquier, Gil Rabinovici, Philippe Robert, Christopher Rowe, Stephen Salloway, Marie Sarazin, Stéphane Epelbaum, Leonardo C de Souza, Bruno Vellas, Pieter J Visser, Lon Schneider, Yaakov Stern, Philip Scheltens, Jeffrey L Cummings. Advancing research diagnostic criteria for Alzheimer’s disease: the IWG-2 criteria. The Lancet Neurology, 2014; 13 (6): 614 DOI: 10.1016/S1474-4422(14)70090-0