We determined whether a battery of neuropsychological tests could predict who would develop Alzheimer's disease (AD) in a group of 123 memory-impaired nondemented patients. Patients were followed longitudinally for 2 years with a research battery of neuropsychological tests. After 2 years, 29 developed probable AD, and 94 did not develop dementia. We used logistic regression analyses to examine the classification accuracy of subjects' performance at entry to the study on the research battery. The logistic regression model was significant with an accuracy of 89%, sensitivity of 76%, and specificity of 94%. Two tests contributed significantly to this model: the delayed recall from the Rey Auditory Verbal Learning Test and the Mental Control subtest of the Wechsler Memory Scale. These two tests alone produced the same accuracy, sensitivity, and specificity as the larger model. These results demonstrate that probable AD can be predicted with a high degree of accuracy and with a relatively brief battery of neuropsychological tests.

Fatty acid differences, including docosahexaenoic acid (DHA; 22:6n-3) have been shown in the brains of Alzheimer's patients (AD) as compared with normal age-matched individuals. Furthermore, low serum DHA is a significant risk factor for the development of AD. The relative concentration of DHA and other fatty acids, however, in the plasma of AD patients compared with patients with other kinds of dementias (other dementias; OD), patients who are cognitively impaired but nondemented (CIND), or normal patients is not known. In this study we analyzed the total phospholipid, phosphatidylcholine (PC), phosphatidylethanolamine (PE), and lysophosphatidylcholine (lysoPC) fractions of plasma from patients diagnosed with AD, OD, or CIND and compared them with a group of elderly control subjects with normal cognitive functioning. Plasma phospholipid and PC levels of 20:5n-3, DHA, total n-3 fatty acids, and the n-3/n-6 ratio were lower in the AD, OD, and CIND groups. Plasma phospholipid 24:0 was lower in the AD, OD, and CIND groups as compared with the group of control patients, and total n-6 fatty acid levels were higher in the AD and CIND groups only. In the plasma PE fraction, levels of 20:5n-3, DHA, and the total n-3 fatty acid levels were significantly lower in the AD, OD, and CIND groups. DHA levels were lower in the lysoPC fraction of CIND individuals only. There were no other differences in the fatty acid compositions of the different phospholipid fractions. Therefore, in AD, OD, and CIND individuals, low levels of n-3 fatty acids in the plasma may be a risk factor for cognitive impairment and/or dementia. Interestingly, a decreased level of plasma DHA was not limited to the AD patients but appears to be common in cognitive impairment with aging.

Neuropathologic confirmation is required to validate the NINCDS-ADRDA Work Group criteria for the clinical diagnosis of Alzheimer's disease (AD). Neuropathologic inclusion and exclusion criteria for AD, however, are not uniform. The purpose of this investigation was to examine the confirmation rate for the Work Group criteria against differing neuropathologic criteria for AD. The sample consisted of 57 cases, 22 of which had received a clinical diagnosis of AD. Nine neuropathologic criteria for AD were applied in a blind fashion to each of the 57 cases. Our results indicated that, depending on the neuropathologic criteria applied, the clinicopathologic agreement ranged from 64% to 86%. These findings demonstrate the need for universally accepted neuropathologic and clinical criteria for AD.