Variables, including depression timeline/onset and its clinical course, apolipoprotein E4 (APOE4) genotype status, sex, dose/duration of antidepressant treatment, and AD biomarkers need to be incorporated in future trials to better elucidate the effect of antidepressants on AD risk.
Genetic polymorphisms of 4 genes, methylenetetrahydrofolate reductase (MTHFR) and apolipoprotein E (ApoE) have been demonstrated to associate with the increased risk for both MDD and stroke, while the association between identified polymorphisms in angiotensin converting enzyme (ACE) and serum paraoxonase (PON1) with depression is still under debate, for the existing studies are insufficient in sample size.
Individual participant data meta-analyses of multivariable linear mixed model results pooled across cohorts revealed that for at least 1 cognitive outcome, age (B = -0.1, SE = 0.01), APOE*4 carriage (B = -0.31, SE = 0.11), depression (B = -0.11, SE = 0.06), diabetes (B = -0.23, SE = 0.10), current smoking (B = -0.20, SE = 0.08), and history of stroke (B = -0.22, SE = 0.09) were independently associated with poorer cognitive performance (p < 0.05 for all), and higher levels of education (B = 0.12, SE = 0.02) and vigorous physical activity (B = 0.17, SE = 0.06) were associated with better performance (p < 0.01 for both).
Significantly lower plasma melatonin concentration was found in patients with AD but not in controls, who were noncarriers of the APOE ε4 allele, regardless of the presence of depression or the severity of dementia in AD.
Subanalyses were inconclusive for APOE ɛ4-positive participants, although mean anxiety and depression scores were still well below cutoffs for clinical concern.ConclusionTelephone disclosure of APOE results and risk for Alzheimer disease is generally safe and helps providers meet demands for services, even when results identify an increased risk for disease.
Our findings indicate a role of APOE genotype in onset of comorbid depression in a subgroup of patients with AD who are not carriers of the APOE ε4 allele.
In survival analyses, age (hazard ratio [HR] 1.04, 95% 1.03-1.05), baseline Mini-Mental State Exam (HR 0.85, 95% confidence interval 0.83-0.87), amnestic subtype of mild cognitive impairment (HR 1.66, 95% 1.30-2.12), presence of APOE4 allele (HR 1.99, 1.69-2.36), and presence of active depression within the last two years (HR 1.44, 95% confidence interval 1.16-1.79) were all independently associated with increased risk of Alzheimer dementia.
Analyses were adjusted by baseline covariates: age, race, sex, poverty status, marital status, body mass index, smoking status, ApoE4 status, and mCES-D.
As indicated by Cox regression modeling, dementia risk of low-educated individuals was not significantly different between ethnic groups but was related to having an APOE e4 allele (hazard ratio [HR] 1.89), depression (HR 1.67), stroke (HR 1.60), and smoking (HR 1.32).
Depression and dementia in the elderly have been suggested to share similar risk factors and pathogenetic background, and recently the authors reported that the APOEɛ4 allele is a risk factor for both disorders in the general population.
The prevalence of APOE ɛ4 allele was higher in participants with dementia than in controls (50% versus 29.4%; p = 0.0002), as was the prevalence of depression (48% versus 32%; p < 0.001).
Results supported the hypothesized path model (root mean square error of approximation = 0.041; comparative fit index = 0.959); however, APOE-conferred risk was not a significant moderator of the 2004 or 2011 vascular depression effect and only approached significance as a predictor of depression in 2011 (P = .079).
After statistical modelling that controlled for the effects of age, depression and apolipoprotein E genotype, HDL-C was significantly associated with better verbal learning and memory performance, specifically short and long delay-free recalls (F = 3.062; p < .05 and F = 3.2670; p < .05, respectively).
Other highly relevant risk factors were activities of daily living (ADL), instrumental ADL, aging, depression, gender, the APOE ε4 allele, and comorbidities (depression as well as gastrointestinal, osteoarticular, and neurodegenerative diseases).
Demographic data, the Consortium to Establish a Registry for Alzheimer's Disease 10-word delayed recall, APOE ɛ4 status, Cornell Scale for Depression in Dementia, and comorbid hypertension were used as covariates.
Taken together, these results indicate that ApoE4 negatively impacts BDNF-5-HT<sub>2A</sub> signaling in the female brain, which could in part underlie the ApoE4-mediated increased risk for depression.
Abnormal FDG-PET was associated with depression as measured by NPI-Q (OR = 2.12; 1.23-3.64); the point estimate was further elevated for APOE ɛ4 carriers (OR = 2.59; 1.00-6.69), though marginally significant.
In cognitively healthy research participants with a first-degree relative with AD, disclosure of APOE ε4-positivity does not lead to elevated anxiety and depression levels, but does increase test-related distress and results in behavior changes concerning insurance and health.