Alzheimer’s disease studies that focus on the earliest stage of the disease, which is mild cognitive impairment (MCI), have typically focused on short-term memory loss. Now, a study published last month in the American Journal of Psychiatry has concluded that people who develop Alzheimer’s may have shown knowledge based (semantic) impairment prior to memory loss, had they been tested for this cognitive deficit.
Terry Goldberg, PhD, a professor of psychiatry and behavioral science at the Hofstra North Shore-LIJ School of Medicine believes that more attention should be given to studying people who have mild cognitive impairment (MCI) to see if they also have early signs of impaired knowledge based cognition.
In the study, the test given to participants was simple, yet specific. Goldberg and his colleagues wanted to maintain distance from verbal abilities, so they used the size of objects to test the study participants’ cognition.
Goldberg explained that, “If you ask someone what is bigger, a key or an ant, they would be slower in their response than if you asked them what is bigger, a key or a house.” He clarified by explaining that the greater the difference in size between two objects, the faster any person, with or without cognitive decline, can recognize the difference and react to the question.
Researchers recruited 25 patients with MCI, 27 patients with Alzheimer's and 70 cognitively healthy people for testing. During testing, they found large differences between the healthy controls and the MCI and Alzheimer's patients. According to Goldberg, “This finding suggested that semantic processing was corrupted…MCI and AD (Alzheimer's disease) patients are really affected when they are asked to respond to a task with small size differences."
Semantic processing is performed in the left temporal lobe of the brain. According to the researchers, “The semantic system is organized in networks that reflect different types of relatedness or association. Semantic items and knowledge have been acquired remotely, often over many repetitions, and do not reflect recent learning.”
Goldberg believes that this finding is extremely important because it may be possible for therapists to strengthen these semantic processing connections through training. “It tells us that something is slowing down the patient and it is not episodic memory but semantic memory," he said.
While therapy to strengthen semantic processing in people with MCI isn’t going to cure AD, the discovery that this type of memory is critical in the Alzheimer’s disease process is one more step in the knowledge base of scientists looking for a cure.
Newswise. (2012, December 28) Study Shows Early Cognitive Problems Among Those Who Eventually Get Alzheimer's. Retrieved from http://www.newswise.com/articles/view/597687/?sc=rsmn&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+NewswiseMednews+%28Newswise%3A+MedNews%29&utm_content=FeedBurner