Forgetting minor things like where you kept your car keys may be a symptom of subjective cognitive impairment (SCI), which is the earliest sign of cognitive decline.
The latter is marked by situations such as when a person recognizes they can't remember a name like they used to or where they recently placed important objects the way they used to.
Studies have shown that SCI is experienced by between one-quarter and one-half of the population over the age of 65. A new study, published in the January 11, 2010, issue of the journal Alzheimer's & Dementia
, finds that healthy older adults reporting SCI are 4.5 times more likely to progress to the more advanced memory-loss stages of mild cognitive impairment (MCI) or dementia than those free of SCI.
The long-term study completed by researchers at NYU Langone Medical Center tracked 213 adults with and without SCI over an average of seven years, with data collection taking nearly two decades. Further cognitive decline to MCI or dementia was observed in 54 percent of SCI persons, while only in 15 percent of persons free of SCI.
"This is the first study to use mild cognitive impairment as well as dementia as an outcome criterion to demonstrate the outcome of SCI as a possible forerunner of eventual Alzheimer's disease," said Barry Reisberg, MD, professor of psychiatry, director of the Fisher Alzheimer's Disease Program and director, Clinical Core, NYU Alzheimer's Disease Center at NYU Langone Medical Center. "The findings indicate that a significant percentage of people with early subjective symptoms may experience further cognitive decline, whereas few persons without these symptoms decline. If decline does occur in those without SCI symptoms, it takes considerably longer than for those with subjective cognitive symptoms."
According to the authors, scientists and physicians can now target the prevention of eventual Alzheimer's disease in the SCI stage, beginning more than 20 years before dementia becomes evident
"These intriguing results more fully describe the possible relationship between early signs of memory loss and development of more serious impairment. This is critical to know, as we look for ways to define who is at risk and for whom the earliest interventions might be successful," said Neil Buckholtz, PhD, National Institute on Aging (NIA) which supported the research. "These findings also underscore the importance of clinicians' asking about, and listening to, concerns regarding changes in cognition and memory among their aging patients."