How cognition changes before dementia hits

Study finds language-processing difficulties are an indicator - more so than memory loss - of amnestic mild cognitive impairment. Individuals with mild cognitive impairment, especially of the "amnestic subtype" (aMCI), are at increased risk for dementia due to Alzheimer's disease relative to cognitively healthy older adults. Now, a study co-authored by researchers from MIT, Cornell University, and Massachusetts General Hospital has identified a key deficit in people with aMCI, which relates to producing complex language. This deficit is independent of the memory deficit that characterizes this group and may provide an additional "cognitive biomarker" to aid in early detection - the time when treatments, as they continue to be developed, are likely to be most effective. The researchers found that while individuals with aMCI could appreciate the basic structure of sentences (syntax) and their meaning (semantics), they struggled with processing certain ambiguous sentences in which pronouns alluded to people not referenced in the sentences themselves. "These results are among the first to deal with complex syntax and really get at the abstract computation that's involved in processing these linguistic structures," says MIT linguistics scholar Suzanne Flynn, co-author of a paper detailing the results. The focus on subtleties in language processing, in relation to aMCI and its potential transition to dementia such as Alzheimer's disease is novel, the researchers say.