The association between depression and apolipoprotein E (apoE) was investigated in 137 out-patients with Alzheimer's disease. An ICD-10 diagnosis of depression was found in 21.1% of all patients. There was a good correlation between clinicians' diagnoses and blinded rating by the Montgomery-Asberg Depression Rating Scale (r = 0.70). In male patients, apoE 3/3 was detected in 34.1%, 3/4 in 38.6%, 4/4 in 13.6%, 2/4 in 6.8% and 2/3 in 6.8% of cases. In female patients, apoE 3/3 was detected in 35.5%, 3/4 in 45.2%, 4/4 in 12.8%, 2/4 in 3.2% and 2/3 in 3.2% of cases. When analyzing the variance of gene dosage effect, the frequency of the apoE epsilon 4 allele was significantly increased in depressed women but not in men. This effect remained stable in stepwise regression analysis when depression as the dependent variable was tested against the independent variables age, age of onset, duration of disease, cognitive status and years of school education.
