Other Cognitive Abilities Declining in Alzheimer's Disease

From Geriatric Pharmacy Intern, Phuong Pham, PharmD(c)
University of Florida College of Pharmacy

Researchers have been trying to identify the signs and symptoms that can lead to the diagnosis of Alzheimer's disease as early as possible. Alzheimer's disease has been commonly linked to a loss of episodic memory, in which a person fails to remember a past event that has occurred in his or her life. However, according to a study done, they found that other cognitive abilities, besides memory, may start to decline years before the diagnosis of Alzheimer is made. The study had enrolled 444 individuals without dementia between 1979 and 2006. These individuals had a clinical evaluation and a psychometric assessment done, including four cognitive factors: global cognition, verbal memory, visuospatial skill, and working memory. Visuospatial skill means the ability to process and interpret the relationship between objects and their location in space. After an average follow-up of 5.9 years, they found that 134 individuals had developed dementia and 44 with dementia died with a confirmed diagnosis of Alzheimer’s disease. When the researchers graphed the data from the psychometric assessments, they found that there was a sudden and steeper decline in the slope of the visuospatial skills three years before patients with dementia were diagnosed. The global cognition graph showed a steep decline two years before clinical diagnosis of dementia, while verbal and working memory did not show until one year before. The authors concluded, "Some of the earliest signs of preclinical disease may occur on tests of visuospatial and speeded psychomotor skills. Furthermore, the greatest rate of preclinical decline may occur on executive and attention tasks. These findings suggest that research into early detection of cognitive disorders using only episodic memory tasks, such as word lists or paragraph recall, may not be sensitive to either all of the earliest manifestations of disease or the most rapidly changing domain."