Importance of subtle amnestic and nonamnestic deficits in mild cognitive impairment: prognosis and conversion to dementia.

BACKGROUND/AIMS: To evaluate baseline characteristics and conversion to dementia in mild cognitive impairment (MCI) subtypes. METHODS: We prospectively evaluated conversion to dementia in 106 patients with amnestic MCI (A-MCI) as defined by Petersen's operationalized criteria on a paragraph recall task, amnestic-subthreshold MCI (AS-MCI) as defined by impairment on the ADAS-cog delayed word list recall with normal paragraph recall, nonamnestic MCI (NA-MCI) defined by a nonmemory domain, and in 27 patients with subjective memory loss who had no deficit on formal neuropsychological testing. RESULTS: For all MCI subtypes, the 4-year conversion to dementia was 56% (14% annually) and to AD was 46% (11% annually). Conversion to AD in the A-MCI (56%) was similar to the rate in AS-MCI (50%). Conversion to AD in the A-MCI and AS-MCI combined was 56% (14% annually). Conversion to dementia in the NA-MCI was 52% (13% annually) and the majority converted to AD (62%). CONCLUSIONS: All MCI subtypes are at risk of converting to AD if the groups are carefully defined by an abnormal psychometric domain. All subtypes except subjective memory loss converted to AD at higher than expected rates. Both the A-MCI and AS-MCI subtypes had a similarly high rate of conversion to AD. The deficit on a word list recall task may develop before an abnormality on delayed paragraph recall is evident, at least in some subjects.

Memory and MRI-based hippocampal volumes in aging and AD.

OBJECTIVE: To demonstrate structural-functional relationships between MRI-based volumetric measurements of medial temporal lobe structures and cognitive function. BACKGROUND: Previous work has documented the ability of MRI-based measurements of the hippocampus to discriminate between age-matched control subjects and patients with very mild AD. Relatively less is known about the correlation between medial temporal lobe structures and cognitive functions. METHOD: We evaluated structural-functional relationships among the hippocampal formation, parahippocampal gyrus, and amygdala, and measures of memory, language, and general cognitive performance in 220 probable AD patients and normal control subjects. Standardized instruments of memory and general cognitive function were used to assess subjects enrolled in a longitudinal study of aging and dementia. RESULTS: The volume of the hippocampal formation predicted performance on most acquisition and recall measures across the spectrum of normal aging and AD. If the groups were segregated, most of the expected associations between medial temporal lobe structures and memory measures were observed in the AD patients. CONCLUSION: MRI-based hippocampal volumetry accurately depicts the structural-functional relationships between memory loss and hippocampal damage across the spectrum from normal aging to dementia.

Neurodegenerative diseases of Guam: analysis of TAU.

Mutations in the tau gene have been described in families affected by frontotemporal dementia with parkinsonism linked to chromosome 17. The authors performed a genetic and biochemical analysis of this gene and its product in the parkinsonism dementia complex of Guam, a disorder characterized by the extensive formation of neurofibrillary tangles. The tau gene is not a primary cause of the parkinsonism dementia complex of Guam.

Guamanian neurodegenerative disease: electrophysiologic findings.

Amyotrophic lateral sclerosis (ALS), parkinsonism and/or dementia are highly prevalent among the Chamorro population of Guam. The incidence of Guamanian ALS has markedly declined in recent years, but these incidence figures may reflect underascertainment of subclinical disease. Guamanian Chamorro patients have not been systematically studied using modern clinical neurophysiological techniques. Electromyography (EMG: needle exam and nerve conduction studies) was used to study 29 patients with the major subtypes of Guamanian neurodegenerative disease, as well as 11 neurologically normal Guamanian Chamorro subjects. Central conduction was assessed by somatosensory evoked potentials (SEP's) in 16 patients. EMG evidence of peripheral neuropathy, (often subclinical) was found in 45% of Guamanian patients but no Chamorro control subjects. Diabetes mellitus, which is highly prevalent in this population, was present in some, but not all of these cases. Clinically unsuspected motor neuron disease was identified by EMG in only one of the 23 Guamanian patients with parkinsonism and/or dementia and in none of the 11 Chamorro control subjects. Two of seven patients with the clinical phenotype of Guamanian ALS had a more benign EMG pattern on the needle electrode exam with absence of fibrillation and fasciculation potentials. Three of 16 patients (all with parkinsonism and dementia) had mildly abnormal tibial SEP's. No patient had EMG evidence of myopathy or a defect of neuromuscular transmission. We conclude: (1) peripheral neuropathy may be a manifestation of Guamanian neurodegenerative disease; (2) the declining prevalence of ALS on Guam is not associated with the development of a subclinical form of motor neuron disease; (3) the substantial overlap of Guamanian ALS with parkinsonism-dementia reported in prior decades is no longer apparent; (4) abnormal central conduction, as assessed by tibial SEP's, is present in some patients with Guamanian parkinsonism-dementia.

Prediction of AD with MRI-based hippocampal volume in mild cognitive impairment.

OBJECTIVE: To test the hypothesis that MRI-based measurements of hippocampal volume are related to the risk of future conversion to Alzheimer's disease (AD) in older patients with a mild cognitive impairment (MCI). BACKGROUND: Patients who develop AD pass through a transitional state, which can be characterized as MCI. In some patients, however, MCI is a more benign condition, which may not progress to AD or may do so slowly. PATIENTS: Eighty consecutive patients who met criteria for the diagnosis of MCI were recruited from the Mayo Clinic Alzheimer's Disease Center/Alzheimer's Disease Patient Registry. METHODS: At entry into the study, each patient received an MRI examination of the head, from which the volumes of both hippocampi were measured. Patients were followed longitudinally with approximately annual clinical/cognitive assessments. The primary endpoint was the crossover of individual MCI patients to the clinical diagnosis of AD during longitudinal clinical follow-up. RESULTS: During the period of longitudinal observation, which averaged 32.6 months, 27 of the 80 MCI patients became demented. Hippocampal atrophy at baseline was associated with crossover from MCI to AD (relative risk [RR], 0.69, p = 0.015). When hippocampal volume was entered into bivariate models-using age, postmenopausal estrogen replacement, standard neuropsychological tests, apolipoprotein E (APOE) genotype, history of ischemic heart disease, and hypertension-the RRs were not substantially different from that found univariately, and the associations between hippocampal volume and crossover remained significant. CONCLUSION: In older patients with MCI, hippocampal atrophy determined by premorbid MRI-based volume measurements is predictive of subsequent conversion to AD.

Mild cognitive impairment: clinical characterization and outcome.

BACKGROUND: Subjects with a mild cognitive impairment (MCI) have a memory impairment beyond that expected for age and education yet are not demented. These subjects are becoming the focus of many prediction studies and early intervention trials. OBJECTIVE: To characterize clinically subjects with MCI cross-sectionally and longitudinally. DESIGN: A prospective, longitudinal inception cohort. SETTING: General community clinic. PARTICIPANTS: A sample of 76 consecutively evaluated subjects with MCI were compared with 234 healthy control subjects and 106 patients with mild Alzheimer disease (AD), all from a community setting as part of the Mayo Clinic Alzheimer's Disease Center/Alzheimer's Disease Patient Registry, Rochester, Minn. MAIN OUTCOME MEASURES: The 3 groups of individuals were compared on demographic factors and measures of cognitive function including the Mini-Mental State Examination, Wechsler Adult Intelligence Scale-Revised, Wechsler Memory Scale-Revised, Dementia Rating Scale, Free and Cued Selective Reminding Test, and Auditory Verbal Learning Test. Clinical classifications of dementia and AD were determined according to the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition and the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria, respectively. RESULTS: The primary distinction between control subjects and subjects with MCI was in the area of memory, while other cognitive functions were comparable. However, when the subjects with MCI were compared with the patients with very mild AD, memory performance was similar, but patients with AD were more impaired in other cognitive domains as well. Longitudinal performance demonstrated that the subjects with MCI declined at a rate greater than that of the controls but less rapidly than the patients with mild AD. CONCLUSIONS: Patients who meet the criteria for MCI can be differentiated from healthy control subjects and those with very mild AD. They appear to constitute a clinical entity that can be characterized for treatment interventions.

Postmenopausal estrogen replacement therapy and risk of AD: a population-based study.

OBJECTIVE: To study the association between estrogen replacement therapy in postmenopausal women and AD using a case-control design. BACKGROUND: Studies of the effect of estrogen therapy on the risk of AD have been limited and have yielded conflicting results. METHODS: Case patients were all postmenopausal women who developed AD in the quinquennium 1980 through 1984 in Rochester, MN (n = 222). One control subject from the same population and free of dementia was matched to each case patient by age (+/-3 years) and length of enrollment in the records-linkage system (n = 222). Estrogen exposure was defined as any form of estrogen (oral, parenteral, topical, suppository) used for at least 6 months after the onset of menopause and before the onset of AD (or corresponding year in the matched control subject). Information on dose and duration of use was abstracted. Consistent with the matched design, analyses entailed conditional logistic regression. RESULTS: AD patients and control subjects had identical age at menarche (median: 13.0 versus 13.0 years) and age at menopause (median: 50.0 versus 50.0 years). The frequency of estrogen use was higher among control subjects than AD patients (10% versus 5%; odds ratio = 0.42; 95% confidence interval 0.18 to 0.96; p = 0.04). There was a significant trend of decreasing odds ratios with increasing duration of use. The inverse association between estrogen therapy and AD remained significant after adjustment for education and age at menopause. CONCLUSION: These results from a population-based study suggest that estrogen replacement therapy is associated with a reduced risk of AD in postmenopausal women.

Olfactory dysfunction in Guamanian ALS, parkinsonism, and dementia.

OBJECTIVES: To assess whether olfactory deficits are present in the general Guamanian Chamorro population and to evaluate olfaction in each of the four neurodegenerative disease syndromes of Guam: ALS, pure parkinsonism, pure dementia, and the combined parkinsonism-dementia complex (PDC). BACKGROUND: Olfactory dysfunction was previously reported in patients with PDC of Guam. METHODS: We developed a culturally adjusted olfactory test battery, derived from the original University of Pennsylvania Smell Identification Test (UPSIT), and administered this to Chamorro residents with ALS (n=9), pure parkinsonism (n=9), pure dementia (n=11), PDC (n=31), and 53 neurologically normal Chamorro and 25 North American control subjects. RESULTS: Similar, marked olfactory dysfunction was found in all four syndromes of Guamanian neurodegenerative disease. This correlated poorly with measures of parkinsonism and cognition. In the neurologically normal Chamorro control group, six subjects (11%) had very low olfactory scores; these were less than the lowest North American score, raising a question of subclinical neurodegenerative disease. CONCLUSIONS: Marked olfactory deficits are common to all four Guamanian neurodegenerative syndromes, and suggest the possibility of similar central neuropathologic substrates. The deficit in the Guamanian ALS group contrasts with idiopathic ALS, in which olfactory function has been reported to be only slightly compromised.

Nonsteroidal anti-inflammatory drug use and Alzheimer's disease: a case-control study in Rochester, Minnesota, 1980 through 1984.

OBJECTIVE: To compare the frequency of use of nonsteroidal anti-inflammatory drugs (NSAIDs) among 302 incident cases of Alzheimer's disease (AD) and age- and sex-matched control subjects. DESIGN: We undertook a retrospective case-control study, using the resources of the Rochester Epidemiology Project. MATERIAL AND METHODS: In ongoing studies of dementia in Rochester, Minnesota, we identified all incident cases of AD with onset between 1980 and 1984. From among all Rochester residents who received care at Mayo Clinic Rochester during those years, we selected one age- (within 3 years) and sex-matched control subject. For this study, exposure to a prescription NSAID was defined as prescribed use for 7 or more days during the 2-year window of time encompassing the year of onset and the year before onset among cases and the corresponding index year and the year prior for control subjects. RESULTS: The odds ratio (OR) for exposure, as described, to a prescription NSAID versus no exposure to any NSAID was 0.79 (95% confidence interval [CI], 0.45 to 1.38); the OR was 1.00 (95% CI, 0.52 to 1.92) for women and 0.40 (95% CI, 0.13 to 1.29) for men. Similarly, the overall OR for aspirin exposure versus no NSAID exposure was 0.90 (95% CI, 0.54 to 1.50). CONCLUSION: These data are suggestive but not confirmatory of a protective effect of NSAIDs for AD.

Incidence of dementia and Alzheimer's disease: a reanalysis of data from Rochester, Minnesota, 1975-1984.

For both dementia and Alzheimer's disease (AD), data regarding incidence rates in the oldest old and time trends in incidence are limited. The authors reanalyzed previously reported data on the incidence of dementia and AD in Rochester, Minnesota, from 1975 through 1984, using three new strategies. First, incidence rates were corrected by removing age-, sex-, and calendar year-specific prevalent cases from the census-derived denominator figures. Second, incidence figures for persons above age 84 years were disaggregated. Third, time trends were investigated graphically using age-specific curves and birth cohort curves. Dementia diagnosis and AD diagnosis followed defined ad hoc criteria. Analyses were conducted for men, women, and both sexes combined, and for dementia and AD separately. The age-specific incidence rates were similar in men and women, continued to increase after age 84 years, and remained stable over time for both dementia and AD. No birth cohort effect was present for either dementia or AD. The similar risks seen in men and women, the continuing increase in incidence after age 84 years, and the stability of incidence over time have important implications for etiologic research on AD.

Apolipoprotein E genotype influences cognitive 'phenotype' in patients with Alzheimer's disease but not in healthy control subjects.

We examined the association of apolipoprotein E (apo E) genotype with cognitive performance in Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI) patients and in normal subjects. One hundred fifty-seven AD patients, 35 MCI patients who developed AD during longitudinal follow-up, and 341 normal control subjects from the Mayo Clinic Alzheimer's Disease Patient Registry were studied. All participants were typed for apo E using polymerase chain reaction-based assay, epsilon 4+ and epsilon 4- groups were compared on cognitive factor scores of Verbal Comprehension, Perceptual Organization, Attention/Concentration, Learning, and Retention. Raw delayed verbal recall and visual confrontation naming scores supplemented these scores. Multivariate ANOVA was completed for cognitive scores. As expected, a main effect for diagnostic group was present across all scores. Multivariate main effects for age group and apo E genotype were also statistically significant. Subsequent within-group comparisons revealed no genotype differences for control subjects across all cognitive scores except raw delayed recall where an interaction indicated that older epsilon 4+ control subjects actually scored better than younger epsilon 4+ patients. Genotype differences were present for the Retention factor in the MCI sample and for Verbal Comprehension and Learning in the AD sample. In a combined cognitive impairment sample (AD + MCI), genotype differences were present for Verbal Comprehension, Learning, and Retention. Possession of an apo E epsilon 4 allele did not appear to be associated with poorer cognitive performance among normal control subjects. In the AD and MCI samples, epsilon 4+ status was associated with greater memory impairment in analyses including duration of illness as a covariate. In combined AD + MCI analyses, epsilon 4 homozygosity was associated with poorer retention, learning, and verbal comprehension at a given disease duration. Possession of the epsilon 4 genotype may influence cognition in a dose-response relationship.

Hippocampal atrophy and apolipoprotein E genotype are independently associated with Alzheimer's disease.

A variety of anatomic and functional neuroimaging findings are associated with Alzheimer's disease (AD). One of the strongest imaging associations identified is between AD and hippocampal atrophy. The epsilon4 allele of the apolipoprotein E (ApoE) gene increases the risk of developing AD and lowers the mean age of onset of the disease. The purpose of this study was to assess the association between hippocampal volume and ApoE polymorphisms in elderly control subjects and in patients with probable AD. We performed magnetic resonance imaging-based volume measurements of the hippocampus in 125 cognitively normal elderly controls and 62 patients with probable AD. ApoE genotyping was performed by using standard methods. Hippocampal volumes were significantly smaller in AD cases than in control subjects. Hippocampal volumes did not differ significantly within either clinical group on the basis of ApoE genotype. Both the epsilon4 allele of ApoE and hippocampal atrophy were significantly but independently associated with AD.

Autonomic failure in Guamanian neurodegenerative disease.

Autonomic impairment is minor in idiopathic amyotrophic lateral sclerosis (ALS) and Alzheimer's-type dementia (D) and is usually not marked in Parkinson's disease. The autonomic status of Guamanian parkinsonism (P), ALS, and parkinsonism-dementia complex (PDC) is essentially unknown. We therefore evaluated the autonomic nervous system in Guamanian D, ALS, P, and PDC. Cardiovagal, adrenergic, and postganglionic sudomotor functions were quantitated in 16 patients and 14 paired household controls. Patients comprised PDC (N = 11), D (N = 2), P (N = 2), and ALS (N = 1). Autonomic deficit was expressed on a composite autonomic scoring scale (CASS) and its subsets that corrects for the effects of age and gender. CASS severity was rated from 0 to 10 and the maximal subset scores were 3, 3, and 4 for postganglionic sudomotor, cardiovagal, and adrenergic deficits, respectively. CASS scores for mild, moderate, and severe autonomic failure are 1 to 3, 4 to 6, and 7 to 10, respectively. Symptoms were scored by an Autonomic Symptom Profile (ASP). The affected patients were older than and had a sex distribution different from paired controls (64.2 +/- 8.0 versus 53.1 +/- 13.5; p < 0.01; male/female = 9/7 versus 2/12; p = 0.045). CASS scores were markedly increased over paired controls (6.2 +/- 2.3 versus 1.9 +/- 1.3; p < 0.001), and involvement was generalized by system. There were deficits in sudomotor, cardiovagal, and adrenergic function. Orthostatic hypotension occurred in 6 of 16 patients and 2 of 14 paired controls. Guamanian patients had more autonomic dysfunction than non-Guamanian Parkinson's disease. ASP scores were higher in patients than controls and regressed with CASS. These differences persisted when corrected for the confounding effects of age, gender, and diabetes. We conclude that Guamanian patients have autonomic failure to a greater extent than non-Guamanian Parkinson's disease or ALS. This autonomic failure suggests multisystem autonomic involvement similar to but less severe than in multiple system atrophy.

Medial temporal atrophy on MRI in normal aging and very mild Alzheimer's disease.

Magnetic resonance imaging (MRI)-based volumetric measurements of medial temporal lobe (MTL) structures can discriminate between normal elderly control subjects and patients with Alzheimer's disease (AD) of moderate to advanced severity. In terms of clinical utility, however, a more important issue concerns the ability of the technique to differentiate between normal elderly control subjects and AD patients with the very mildest form of the disease. We performed MRI-based volumetric measurements of the hippocampus, parahippocampal gyrus, and amygdala in 126 cognitively normal elderly control subjects and 94 patients with probable AD. The diagnosis of AD was made according to NINDS/ADRDA criteria, and disease severity was categorized by Clinical Dementia Rating (CDR) scores. Patients with CDR 0.5 were classified as very mild, CDR 1 as mild, and CDR 2 as moderate disease severity. Volumes of each structure declined with increasing age in control subjects and did so in parallel for men and women. The volume of each measured MTL structure also declined with age in patients with AD. The volume of each MTL structure was significantly smaller in AD patients than control subjects (p < 0.001). Of the several MTL measures, the total hippocampal volumetric measurements were best at discriminating control subjects from AD patients. The mean hippocampal volumes for AD patients relative to control subjects by severity of disease were as follows: very mild AD (CDR 0.5) -1.75 SD below the control mean, mild AD (CDR 1) -1.99 SD, and moderate AD (CDR 2) -2.22 SD. Age- and gender-adjusted, normalized MRI-based hippocampal volumetric measurements provide a sensitive marker of the MTL neuroanatomic degeneration in AD early in the disease process.

Comorbidity of dementia and psychiatric disorders in older persons.

To further investigate the relationship between psychiatric disorders and dementia in elderly patients, the authors drew a population-based, age-stratified random sample from residents of Rochester, Minnesota, age 65 and older. A trained paramedic completed a 90-minute screening interview, including the Symptom Checklist-90, Mini-Mental State Exam, and Auditory-Verbal Learning Test. Persons failing the screens were interviewed by a psychiatrist and a neurologist. DSM-III-R diagnoses were assigned for dementia and other psychiatric disorders. Of 201 participants, 37 were evaluated further by both neurologist and psychiatrist. One received a psychiatric diagnosis alone. Dementia alone was present in four people. Concurrent psychiatric diagnoses and dementia were found in 17 subjects. Much of the psychopathology found in older persons occurs in people with cognitive impairment. Current diagnostic nosology may not be able to capture the interrelatedness of psychiatric syndromes and cognitive impairment in elderly patients.

Guamanian neurodegenerative disease: are diabetes mellitus and altered humoral immunity clues to pathogenesis?

On the western Pacific island of Guam, parkinsonism, dementia, and amyotrophic lateral sclerosis are highly prevalent but the cause is not known. To assess the possibility that the pathologic process extends beyond the nervous system, we studied patients with Guamanian neurodegenerative disease (N = 16) and Guamanian Chamorro control subjects (N = 16) in the Clinical Research Center of the Mayo Clinic, Rochester, MN. The principal abnormalities found in those with neurodegenerative disease included diabetes mellitus in 44%, elevated levels of serum immunoglobulin A (IgA) in 50%, and elevated IgG in 44%. The mean serum IgM level in the patient group was significantly lower than in the control group. Diabetes mellitus and elevated IgA and IgG levels were also present in 31% of neurologically normal Guamanian subjects. Some of these control subjects, however, probably have preclinical neurodegenerative disease, as found in previously published postmortem studies. Extensive serologic testing did not reveal any consistent profile of autoimmunity. Other blood and urine studies failed to identify hematologic, nutritional, renal, hepatic, or metabolic abnormalities that distinguished patients. Whether diabetes mellitus or abnormalities of immune regulation share common etiopathology with Guamanian neurodegenerative disease deserves further study.

Guamanian neurodegenerative disease: ultrastructural studies of skin.

It is evident that Guamanian amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia complex (PDC) are clinical variants of a single disease entity and that Guamanian ALS is clinically indistinguishable from sporadic ALS. We studied by electron microscopy the skin tissues from 11 patients with Guamanian neurodegenerative disease (PDC and ALS), 11 Chamorro control subjects, 10 Japanese patients with sporadic ALS and 11 Japanese control patients. Among patients with sporadic ALS, there was an inverse relationship of collagen fiber diameter and the duration of disease and a marked increase of amorphous material in the ground substance. These findings were not observed in the Guamanian patients or controls. Therefore, the skin studies reinforce the view of a different disease mechanism in Guamanian ALS and PDC compared to sporadic ALS.

Response of the pupil to tropicamide is not a reliable test for Alzheimer disease.

OBJECTIVE: To confirm the putative hypersensitivity of the pupil to a weak mydriatic in persons with Alzheimer dementia. DESIGN: Twenty patients with Alzheimer dementia and 20 control subjects were examined. Automated binocular infrared pupillography was performed in the dark after instillation of 0.01% tropicamide or placebo. Ocular penetration of eye drops was assessed simultaneously using 2% fluorescein sodium as a tracer. SETTING: Rochester, Minn. SUBJECTS: Twenty patients and 20 cognitively normal control subjects from the Alzheimer's Disease Patient Registry of the Mayo Clinic, Rochester, Minn. MAIN OUTCOME MEASURE: Percent change in the diameter of the pupil following topical ocular instillation of a diluted concentration of the mydriatic drug tropicamide and penetration of topically applied fluorescein into the aqueous humor. RESULTS: No statistically significant difference was found between patients with Alzheimer disease and control subjects in either the mydriatic response of the pupil or in the rate of penetration of topically applied fluorescein. CONCLUSION: No evidence of pupillary hypersensitivity to an anticholinergic mydriatic drug was found in patients with Alzheimer disease or any evidence that this putative hypersensitivity could be used as an early, simple diagnostic test for Alzheimer disease.

Aging, memory, and mild cognitive impairment.

In recent years, patients who are at high risk for developing Alzheimer's disease (AD) have become a focus of study. Several research groups have identified these patients, developed diagnostic criteria, and followed the patients longitudinally. These patients therefore constitute a clinical entity that is suitable for therapeutic interventions. In this article, we report our 5-year experience at the Mayo Clinic in characterizing a group of patients with mild cognitive impairment. These subjects were recruited from community-dwelling individuals who were receiving general medical care in the Department of Internal Medicine. They received the diagnosis of mild cognitive impairment if they met the following criteria: (a) complaint of defective memory, (b) normal activities of daily living, (c) normal general cognitive function, (d) abnormal memory function for age, and (e) absence of dementia. In following more than 75 of these patients, some of whom have been studied for as long as 5 years, it appears that approximately 10% to 15% of the subjects evolve to AD each year. We therefore evaluated the cognitive profiles of these patients at the time of their initial diagnosis in an attempt to predict who would remain stable and who would evolve to AD. Certain features of learning and memory performance indicated patients who were more likely to progress, but the strongest predictor was their apolipoprotein E status. The patients who possessed an epsilon 4 allele were more likely to convert to AD at a more rapid rate then those who were not carriers. Our results and similar data from other study groups indicate that diagnostic criteria can be defined for patients who are likely to convert to AD; the natural history of these patients is becoming apparent, and variables that predict ultimate conversion can be defined. Consequently, patients with mild cognitive impairment constitute an important group for study, particularly form the aspect of therapeutic interventions.