[Isoform 4 of apolipoprotein E and Alzheimer disease. Specificity and clinical study].

We studied apolipoprotein E (apoE) phenotype in 113 patients with possible and probable Alzheimer's disease (AD), 49 patients with Parkinson's disease (including 11 patients with dementia) and 23 patients with mixed and vascular dementia. Normal controls were 498 young, healthy blood donors previously recorded. All patients were assayed for blood lipid parameters. All AD patients underwent a neuropsychological evaluation (including a mini-mental status and 5 subtests of Cole and Dastoor hierarchic dementia scale) and a detailed interrogation of them and their caregivers about their familial and personal medical history. The recorded data included age at onset, clinical subtype (i.e. amnesic or aphaso-apraxic), occurrence of fits, cases of probable dementia in relatives, and ages of their parents at death. There was a significant association between the fourth isoform of apoE and AD, as in previous works. We did not found such an association for PD patients (even with dementia) nor mixed and vascular demented patients. We failed to find any association between any clinical characteristic of the patients and the biological subgroups defined by the number of epsilon 4 alleles, except with regard for the age of onset. Surprisingly, the mothers of epsilon 4 bearers had a significantly longer life than mothers of other patients. We failed to found any significant difference of apoE2 isoform frequency between AD patients and controls. AD patients had higher levels of cholesterol and apoAl than did MP and mixed and vascular demented patients. ApoAl level is known to constitute a protective factor against coronary heart disease, which is usually increased by the presence of apoE-epsilon 4.(ABSTRACT TRUNCATED AT 250 WORDS)