Lack of Association between the Apolipoprotein E Genotype and Depression in Alzheimer's Disease

Abstract

The epsilon4 allele of apolipoprotein (apo E) is one of the risk factors for late-onset Alzheimer's disease (AD). We evaluated the association between apo E genotypes and depression in patients with AD. A psychiatrist interviewed all patients and their caregivers for depression using a Chinese version of the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised, and for the severity of depression using the Hamilton Depression Rating Scale (HDRS). Twenty-five of the 149 patients with AD were diagnosed with depressive disorders. The numbers of patients in each apo E genotype were 10 in epsilon2/3, 2 in epsilon2/4, 74 in epsilon3/3, 46 in epsilon3/4, and 17 in epsilon4/4. We did not find an association between depression and the presence or absence of the epsilon4 or epsilon2 allele. The HDRS scores were not different in patients with AD with the epsilon4 or epsilon2 allele or in those patients without them. Our study did not find an association between depression and the apo E epsilon4 or epsilon2 allele in AD.

APOE genotype predicts depression in women with Alzheimer's disease: a retrospective study

“…A recent study suggested that depression and APOE ε4 genotype may be higher in women with AD but not in men (Muller-Thomsen et al, 2002). Despite these findings supporting an association between APOE and depression, several other published studies have not supported the notion that APOE ε4 genotype influences depression in AD (Liu et al, 2002;Scarmeas, et al, 2002;Craig et al, 2005).…”

“…A recent study suggested that depression and APOE ε4 genotype may be higher in women with AD but not in men (Muller-Thomsen et al, 2002). Despite these findings supporting an association between APOE and depression, several other published studies have not supported the notion that APOE ε4 genotype influences depression in AD (Liu et al, 2002;Scarmeas, et al, 2002;Craig et al, 2005).Discrepant findings may be due to a number of factors including small sample sizes, differences in sample compositions (e.g., general "dementia" groups versus strictly diagnosed patients with "probable AD"), and the use of very brief, wide-ranging, or unstructured psychopathology inventories. In addition, others have shown trends toward association between APOE genotype and depression but have rendered conclusions of no relationship.…”

“…These highly variable findings may represent significant heterogeneity within depressed groups. For example, Liu et al (2002) included a large proportion of patients with Dysthymic Disorder in their sample (52%) whereas our study contained only 3% with Dysthymia. It appears that greater specification of diagnostic categories is clearly needed to inspect for important subgroup differences.…”

“…One possible explanation for our positive finding and its absence in prior studies may be that we obtained a relatively large sample of depressed AD patients and thus had a greater power to detect group differences. Several recent studies (i.e., Forsell et al, 1997;Liu et al, 2002;Gabryelewicz et al, 2002) included between 21 and 39 depressed individuals, whereas the current study included approximately twice those sample sizes (i.e., 61 depressed AD patients) and many more nondepressed patients. Another factor may be that the use of limited screening measures for determining depression could be leading to poorer diagnostic accuracies and thus different prevalence rates of depression in AD.…”

Genetic Susceptibility to Behavioural and Psychological Symptoms in Alzheimer Disease

“…However, some work suggested that the APOE epsilon4 genotype may be overrepresented in AD depressed patients or among depressed women with AD [42,43]. Other researchers have not confirmed an additional role for APOE in conferring risk to ADrelated depression [44,45].…”