Although FTD and SemD are associated with different overall patterns of brain atrophy, regions of gray matter tissue loss in the orbital frontal, insular, and anterior cingulate regions are present in both groups. The authors suggest that pathology in the areas of atrophy associated with both FTD and SemD may underlie some the behavioral symptoms seen in the two disorders.

These results indicate that AD alone, in the absence of clinically confirmed extrapyramidal dysfunction, is associated with motor slowing in a stage-dependent manner. It remains to be determined whether this motor slowing represents a general characteristic of mild AD or indicates other neuropathology such as PD or the Lewy body variant of AD.

Pathologically confirmed preclinical AD is not associated with cognitive impairment or decline, even on measures shown to be sensitive to very mild DAT.

The concept of age-associated memory impairment (AAMI) suggests that clinically recognized memory dysfunction can be a feature of normal aging. To determine whether AAMI represents a variant of normal aging, we longitudinally studied individuals meeting AAMI criteria for development of dementia. Two hundred two community-living individuals (mean age, 77 years) with or without mild memory impairment were assessed annually for an average of 3 years at the Washington University Alzheimer's Disease Research Center. At baseline, no individual was unequivocally demented, as defined by a Clinical Dementia Rating (CDR) score of 1 or greater. Modified National Institute of Mental Health criteria were used to identify individuals with AAMI who otherwise met a criterion for cognitive normality. The Short Blessed Test (SBT) was used as a measure of general cognitive function; conservative (SBT = 5) and permissive (SBT = 10) cutoff scores were used as indicators of cognitive normality. With the more permissive measure of cognitive normality, 59 (29%) of the 202 individuals met AAMI criteria. Progression to dementia by 3 years occurred in 42% of AAMI individuals versus 16% of the individuals who did not meet AAMI criteria. With the more restrictive SBT cutoff of 5, 22% of individuals met AAMI criteria; progression to dementia occurred in 31% of these individuals versus 9% of the individuals without AAMI. Survival times to dementia differed significantly between AAMI and non-AAMI groups defined by either cutoff score. Our findings indicate that individuals with AAMI have a three-fold greater risk for development of dementia than individuals who do not meet AAMI criteria. Hence, AAMI may represent a dementia prodrome rather than a benign variant of aging.

This study evaluated the early cognitive and neurobehavioral outcomes of older adults with mild versus moderate traumatic brain injury (TBI). Thirty-five patients who were age 50 years and older and sustained mild or moderate TBI were prospectively recruited from acute care hospitals. Patients were administered cognitive and neurobehavioral measures up to 2 months post-injury. Demographically comparable control participants received the same measures. Patients and controls did not have previous histories of substance abuse, neuropsychiatric disturbance, dementia, or neurologic illness. Moderate TBI patients performed significantly poorer than mild TBI patients and controls on most cognitive measures, whereas the mild patients performed comparably to controls. In contrast, both mild and moderate patients exhibited significantly greater depression and anxiety/somatic concern than controls. The results indicate that the classification of TBI as mild versus moderate is prognostically meaningful as applied to older adults. The findings extend previous investigations in young adults by demonstrating a relatively good cognitive outcome on objective measures, but subjective complaints after a single, uncomplicated mild TBI in older persons. (JINS, 2001, 7, 373–383.)