Novel late-onset Alzheimer disease loci variants associate with brain gene expression

OBJECTIVE

Recent genome-wide association studies (GWAS) of late-onset Alzheimer disease (LOAD) identified 9 novel risk loci. Discovery of functional variants within genes at these loci is required to confirm their role in Alzheimer disease (AD). Single nucleotide polymorphisms that influence gene expression (eSNPs) constitute an important class of functional variants. We therefore investigated the influence of the novel LOAD risk loci on human brain gene expression.

METHODS

We measured gene expression levels in the cerebellum and temporal cortex of autopsied AD subjects and those with other brain pathologies (∼400 total subjects). To determine whether any of the novel LOAD risk variants are eSNPs, we tested their cis-association with expression of 6 nearby LOAD candidate genes detectable in human brain (ABCA7, BIN1, CLU, MS4A4A, MS4A6A, PICALM) and an additional 13 genes ±100 kb of these SNPs. To identify additional eSNPs that influence brain gene expression levels of the novel candidate LOAD genes, we identified SNPs ±100 kb of their location and tested for cis-associations.

RESULTS

CLU rs11136000 (p = 7.81 × 10(-4)) and MS4A4A rs2304933/rs2304935 (p = 1.48 × 10(-4)-1.86 × 10(-4)) significantly influence temporal cortex expression levels of these genes. The LOAD-protective CLU and risky MS4A4A locus alleles associate with higher brain levels of these genes. There are other cis-variants that significantly influence brain expression of CLU and ABCA7 (p = 4.01 × 10(-5)-9.09 × 10(-9)), some of which also associate with AD risk (p = 2.64 × 10(-2)-6.25 × 10(-5)).

CONCLUSIONS

CLU and MS4A4A eSNPs may at least partly explain the LOAD risk association at these loci. CLU and ABCA7 may harbor additional strong eSNPs. These results have implications in the search for functional variants at the novel LOAD risk loci.

Common variants at MS4A4/MS4A6E, CD2AP, CD33 and EPHA1 are associated with late-onset Alzheimer's disease

The Alzheimer Disease Genetics Consortium (ADGC) performed a genome-wide association study of late-onset Alzheimer disease using a three-stage design consisting of a discovery stage (stage 1) and two replication stages (stages 2 and 3). Both joint analysis and meta-analysis approaches were used. We obtained genome-wide significant results at MS4A4A (rs4938933; stages 1 and 2, meta-analysis P (P(M)) = 1.7 × 10(-9), joint analysis P (P(J)) = 1.7 × 10(-9); stages 1, 2 and 3, P(M) = 8.2 × 10(-12)), CD2AP (rs9349407; stages 1, 2 and 3, P(M) = 8.6 × 10(-9)), EPHA1 (rs11767557; stages 1, 2 and 3, P(M) = 6.0 × 10(-10)) and CD33 (rs3865444; stages 1, 2 and 3, P(M) = 1.6 × 10(-9)). We also replicated previous associations at CR1 (rs6701713; P(M) = 4.6 × 10(-10), P(J) = 5.2 × 10(-11)), CLU (rs1532278; P(M) = 8.3 × 10(-8), P(J) = 1.9 × 10(-8)), BIN1 (rs7561528; P(M) = 4.0 × 10(-14), P(J) = 5.2 × 10(-14)) and PICALM (rs561655; P(M) = 7.0 × 10(-11), P(J) = 1.0 × 10(-10)), but not at EXOC3L2, to late-onset Alzheimer's disease susceptibility.

Depression and coronary heart disease: a review for cardiologists

Major depression is a common comorbid condition in patients with coronary heart disease (CHD). Although mild emotional distress may be a normal reaction to myocardial infarction or other manifestations of CHD, major depression should not be considered a normal reaction, nor should it be ignored. Major depression is a debilitating comorbid disorder that can seriously complicate recovery and increase the risks of further cardiac morbidity and mortality. Fortunately, it is one that can be successfully treated in the majority of cases. The purpose of this review is to present the evidence for the negative prognostic effects of depression in cardiac patients and to discuss methods for assessing and treating depression in these patients.

No association between SNP rs498055 on chromosome 10 and late-onset Alzheimer disease in multiple datasets

SNP rs498055 in the predicted gene LOC439999 on chromosome 10 was recently identified as being strongly associated with late-onset Alzheimer disease (LOAD). This SNP falls within a chromosomal region that has engendered continued interest generated from both preliminary genetic linkage and candidate gene studies. To independently evaluate this interesting candidate SNP we examined four independent datasets, three family-based and one case-control. All the cases were late-onset AD Caucasian patients with minimum age at onset >or= 60 years. None of the three family samples or the combined family-based dataset showed association in either allelic or genotypic family-based association tests at p < 0.05. Both original and OSA two-point LOD scores were calculated. However, there was no evidence indicating linkage no matter what covariates were applied (the highest LOD score was 0.82). The case-control dataset did not demonstrate any association between this SNP and AD (all p-values > 0.52). Our results do not confirm the previous association, but are consistent with a more recent negative association result that used family-based association tests to examine the effect of this SNP in two family datasets. Thus we conclude that rs498055 is not associated with an increased risk of LOAD.

Identification of MeCP2 mutations in a series of females with autistic disorder

Rett disorder and autistic disorder are both pervasive developmental disorders. Recent studies indicate that at least 80% of Rett Disorder cases are caused by mutations in the methyl-CpG-binding protein 2 (MeCP2) gene. Since there is some phenotypic overlap between autistic disorder and Rett disorder, we analyzed 69 females clinically diagnosed with autistic disorder for the presence of mutations in the MeCP2 gene. Two autistic disorder females were found to have de novo mutations in the MeCP2 gene. These data provide additional evidence of variable expression in the Rett disorder phenotype and suggest MeCP2 testing may be warranted for females presenting with autistic disorder.

Sex differences in chest pain in patients with documented coronary artery disease and exercise-induced ischemia: Results from the PIMI study

BACKGROUND

Sex differences in the pathophysiologic course of coronary artery disease (CAD) are widely recognized, yet accurate diagnosis of coronary artery disease in women remains challenging.

METHODS

To determine sex differences in the clinical manifestation of CAD, we studied chest pain reported during daily activities, exercise, and mental stress in 170 men and 26 women. All patients had documented CAD (>50% narrowing in at least 1 major coronary artery or prior myocardial infarction) and all had 1-mm ST-segment depression on treadmill exercise. We collected psychologic test results, serum samples (potassium, epinephrine, norepinephrine, cortisol, b-endorphin, and glucose), and cardiac function, sensory threshold, and autonomic function data at specified times before, during, or after exercise and mental stress tests to assess measures of depression, anxiety, and neurohormonal and thermal pain perception.

RESULTS

Women reported chest pain more often than men during daily activities (P =.04) and during laboratory mental stressors (P =.01) but not during exercise. Men had lower scores than women on measures of depression, trait anxiety, harm avoidance, and reward dependence (P <.05 for all). Women had significantly lower plasma b-endorphin levels at rest (4.2 +/- 3.9 vs 5.0 +/- 2.5 pmol/L for men, P =.005) and at maximal mental stress (6.4 +/- 5.1 vs 7.4 +/- 3.5 pmol/L for men, P <.01). A higher proportion of women than men had marked pain sensitivity to graded heat stimuli applied to skin (hot pain threshold <41 degrees C, 33% vs 10%, P =.001).

CONCLUSIONS

Our results reflect sex differences in the affective and discriminative aspects of pain perception and may help explain sex-related differences in clinical presentations.

Depression, heart rate variability, and acute myocardial infarction

BACKGROUND

Clinical depression is associated with an increased risk for mortality in patients with a recent myocardial infarction (MI). Reduced heart rate variability (HRV) has been suggested as a possible explanation for this association. The purpose of this study was to determine if depression is associated with reduced HRV in patients with a recent MI.

METHODS AND RESULTS

Three hundred eighty acute MI patients with depression and 424 acute MI patients without depression were recruited. All underwent 24-hour ambulatory electrocardiographic monitoring after hospital discharge. In univariate analyses, 4 indices of HRV were significantly lower in patients with depression than in patients without depression. Variables associated with HRV were then compared between patients with and without depression, and potential confounds were identified. These variables (age, sex, diabetes, and present cigarette smoking) were entered into an analysis of covariance model, followed by depression status. In the final model, all but one HRV index (high-frequency power) remained significantly lower in patients with depression than in patients without depression.

CONCLUSIONS

We conclude that greater autonomic dysfunction, as reflected by decreased HRV, is a plausible mechanism linking depression to increased cardiac mortality in post-MI patients.

Change in heart rate and heart rate variability during treatment for depression in patients with coronary heart disease

OBJECTIVE

Major depression is a common problem in patients with coronary heart disease (CHD) and is associated with an increased risk for cardiac morbidity and mortality. It is not known whether treating depression will improve medical prognosis in patients with CHD. Depression is also associated with elevated heart rate and reduced heart rate variability (HRV), which are known risk factors for cardiac morbidity and mortality that may explain the increased risk associated with depression. The purpose of this study was to determine whether treatment for depression with cognitive behavior therapy (CBT) is associated with decreased heart rate or increased HRV.

METHODS

Thirty depressed patients with stable CHD, classified as either mildly or moderately to severely depressed, received up to 16 sessions of CBT. The 24-hour heart rate and HRV were measured in these patients and in 22 medically comparable nondepressed controls before and after treatment of the depressed patients.

RESULTS

Average heart rate and daytime rMSSD (reflecting mostly parasympathetic activity) improved significantly in the severely depressed patients, but remained unchanged in the mildly depressed and the control patients. However, only rMSSD improved to a level comparable to the control patients. None of the remaining indices of HRV showed improvement.

CONCLUSIONS

The results suggest that treating depression with CBT may reduce heart rate and increase short-term HRV. Thus, CBT may have a beneficial effect on a risk factor for mortality in depressed patients with coronary heart disease. A randomized, controlled study is needed to confirm these findings.

Psychosocial considerations in elderly patients with heart failure

Neuropsychiatric conditions, such as Alzheimer's dementia, and complications, such as delirium, are common in elderly patients with heart failure. Persistent alcohol abuse and cigarette smoking sometimes contribute to the onset and progression of heart failure. Major depression and other depressive disorders are common in this population and have adverse effects on functional status, quality of life, and prognosis. Anxiety and social isolation are clinically significant problems in many cases. These problems often are treatable and deserve more clinical attention than they typically receive.

Depression and poor glycemic control: a meta-analytic review of the literature

OBJECTIVE

Depression is common among patients with diabetes, but its relationship to glycemic control has not been systematically reviewed. Our objective was to determine whether depression is associated with poor glycemic control.

RESEARCH DESIGN AND METHODS

Medline and PsycINFO databases and published reference lists were used to identify studies that measured the association of depression with glycemic control. Meta-analytic procedures were used to convert the findings to a common metric, calculate effect sizes (ESs), and statistically analyze the collective data.

RESULTS

A total of 24 studies satisfied the inclusion and exclusion criteria for the meta-analysis. Depression was significantly associated with hyperglycemia (Z = 5.4, P < 0.0001). The standardized ES was in the small-to-moderate range (0.17) and was consistent, as the 95% CI was narrow (0.13-0.21). The ES was similar in studies of either type 1 or type 2 diabetes (ES 0.19 vs. 0.16) and larger when standardized interviews and diagnostic criteria rather than self-report questionnaires were used to assess depression (ES 0.28 vs. 0.15).

CONCLUSIONS

Depression is associated with hyperglycemia in patients with type 1 or type 2 diabetes. Additional studies are needed to establish the directional nature of this relationship and to determine the effects of depression treatment on glycemic control and the long-term course of diabetes.

Severe depression is associated with markedly reduced heart rate variability in patients with stable coronary heart disease

OBJECTIVE

The purpose of this study was to investigate the relationship between depression and heart rate variability in cardiac patients.

METHODS

Heart rate variability was measured during 24-hour ambulatory electrocardiographic (ECG) monitoring in 40 medically stable out-patients with documented coronary heart disease meeting current diagnostic criteria for major depression, and 32 nondepressed, but otherwise comparable, patients. Patients discontinued beta-blockers and antidepressant medications at the time of study. Depressed patients were classified as mildly (n = 21) or moderately-to-severely depressed (n = 19) on the basis of Beck Depression Inventory scores.

RESULTS

There were no significant differences among the groups in age, gender, blood pressure, history of myocardial infarction, diabetes, or smoking. Heart rates were higher and nearly all indices of heart rate variability were significantly reduced in the moderately-to-severely versus the nondepressed group. Heart rates were also higher and mean values for heart rate variability lower in the mildly depressed group compared with the nondepressed group, but these differences did not attain statistical significance.

CONCLUSION

The association of moderate to severe depression with reduced heart rate variability in patients with stable coronary heart disease may reflect altered cardiac autonomic modulation and may explain their increased risk for mortality.

Can treating depression reduce mortality after an acute myocardial infarction?

Major depression affects about one in five patients in the weeks after an acute myocardial infarction and is associated with an increased risk of cardiac morbidity and mortality. Consequently, there is considerable interest in the question of whether treating depression will improve medical prognosis in these patients. Safe, effective treatments for depression are available, but unless they also improve the underlying pathophysiological or behavioral mechanisms that contribute to cardiac morbidity and mortality, they may not have beneficial effects on prognosis. Altered cardiac autonomic tone is one of the leading candidate mechanisms. Unfortunately, a review of the available research reveals that cardiac autonomic tone often fails to normalize in patients treated for depression, and the research suggests that currently available treatments for depression will not necessarily improve cardiac event-free survival in patients who have had an acute myocardial infarction. Until there is convincing evidence that treatment can reduce the risk of cardiac morbidity and mortality, the principal reason to treat depression should continue to be to improve the quality of life of the patient who has had an acute myocardial infarction. Key words: depression, coronary heart disease, mortality.

Major depression, heart rate, and plasma norepinephrine in patients with coronary heart disease

BACKGROUND

Although it is now well established that psychiatric depression is associated with adverse outcomes in patients with coronary heart disease (CHD), the mechanism underlying this association is unclear. Elevated heart rate (HR) and plasma norepinephrine (NE), possibly reflecting altered autonomic nervous system activity, have been documented in medically well depressed psychiatric patients, and this pattern is associated with increased risk for cardiac events in patients with CHD. The purpose of this study was to determine whether autonomic nervous system activity is altered in depressed CHD patients.

METHODS

HR, plasma NE, and blood pressure (BP) were measured in 50 depressed and 39 medically comparable nondepressed CHD patients at rest and during orthostatic challenge.

RESULTS

Resting HR (p = .005), and the change from resting HR at 2, 5, and 10 min after standing (p = .02, .004, and .02, respectively), were significantly higher in the depressed than in the nondepressed patients. There were no differences between the groups in NE or in BP at rest, or in standing minus resting change scores at any time during orthostatic challenge (p < .05).

CONCLUSIONS

Depression is associated with altered autonomic activity in patients with CHD, as reflected by elevated resting HR and an exaggerated HR response to orthostatic challenge. Previously reported differences in NE levels between depressed and nondepressed patients were not replicated.

Adherence to a prophylactic medication regimen in patients with symptomatic versus asymptomatic ischemic heart disease

Although angina pectoris is the most common symptom of coronary artery disease, some patients do not experience angina during ischemic episodes. The effects of asymptomatic (silent) heart disease on patient self-management have rarely been studied. Studies of other patient populations with asymptomatic illnesses indicate that patients with silent myocardial ischemia might adhere less well to a prophylactic medication regimen than would those with symptomatic ischemia. Depression, a state associated with poor adherence to medical regimens is more common among patients with symptomatic ischemia. For prevention of thromboembolic events, 37 patients with documented ischemic heart disease who denied having anginal symptoms and 28 patients who reported almost daily symptoms were given a 3-week supply of low-dose aspirin packaged in an unobtrusive electronic adherence monitor. All other medications were provided in standard pill bottles. The symptomatic patients removed their prescribed aspirin on 62.4% of the days; the patients with silent ischemia took their medication on 77.3% of the days. Possible explanations for these results, their clinical implications, and directions for future research are discussed.

Reproducibility of mental stress-induced myocardial ischemia in the Psychophysiological Investigations of Myocardial Ischemia (PIMI)

OBJECTIVE

Many patients with coronary artery disease (CAD) develop myocardial ischemia in response to mental stress. This has been documented both in the natural environment and in the laboratory. However, the reproducibility of laboratory mental stress-induced ischemia has not been investigated.

METHOD

Sixty patients with documented CAD and a positive exercise stress test discontinued cardiac medications and underwent two standardized mental stress tests (a timed Stroop Color-Word test and a public speaking task) in a nuclear cardiology laboratory (Visit 1), and repeated this procedure between 2 and 8 weeks later (Visit 2). Measurements of cardiovascular function and neurohormonal responses were obtained throughout testing, and mood state was assessed before and after testing.

RESULTS

Sixty-eight percent of the 56 patients with detailed radionuclide data from both visits had consistent responses (ie, ischemia either present during both sessions or absent during both) to the Stroop task (kappa = .29, p = .03), 61% had consistent responses to the speech task (kappa = .20, p = .12), and 60% had consistent responses when ischemia was considered present if it occurred during either the Stroop test, the speech task, or both, and absent if it did not occur during either task (kappa = .22, p = .07). Hemodynamic and neuroendocrine responses to the tests were moderately reproducible.

CONCLUSIONS

We conclude that two popular laboratory tests for mental stress-induced myocardial ischemia are modestly reproducible. The relatively low reproducibility is probably influenced by uncertainties in detecting relatively small changes in wall motion, habituation of the patient to repeated exposure to psychological stressors, and physiological differences in threshold for ischemia on different days of testing.

Effects of nortriptyline on depression and glycemic control in diabetes: results of a double-blind, placebo-controlled trial

OBJECTIVE

Depression is a prevalent and chronic condition in diabetes and is associated with poor glucose regulation and poor compliance with diabetes treatment. This investigation evaluated the effects of nortriptyline on depression and glycemic control to see whether depression in diabetes is treatable and whether restoring mental health contributes to improved medical outcome.

METHOD

Sixty-eight diabetic patients with poor glycemic control, 28 of whom had active major depression (DSM-IIIR), completed a randomized, placebo-controlled, double-blind trial involving 8 weeks of treatment with nortriptyline targeted to therapeutic plasma levels (50-150 ng/ml). Depression improvement was determined with the Beck Depression Inventory; glucose control was measured by glycated hemoglobin levels. Compliance behavior was assessed using medication dispensing devices and glucometers equipped with electronic memory.

RESULTS

The reduction in depression symptoms was significantly greater in depressed patients treated with nortriptyline compared with those receiving placebo (-10.2 vs -5.8, p = .03). Nortriptyline was not statistically superior to placebo in reducing glycated hemoglobin of the depressed subjects (p = .5). However, path analysis indicated that the direct effect of nortriptyline was to worsen glycemic control whereas depression improvement had an independent beneficial effect on glycated hemoglobin. These findings were not explained by the relationships of nortriptyline treatment to weight change (r = -0.21, p = .31) or depression improvement to compliance with the protocol for self-monitoring of blood glucose (r = 0.01, p = .97).

CONCLUSIONS

Major depression in diabetic patients can be effectively treated with nortriptyline at the expense of a direct hyperglycemic effect. Path analysis demonstrated a treatment-independent effect of depression improvement on glycemic control, suggesting that a more ideal antidepressant agent may both restore mental health and improve medical outcome.

Angina pectoris after recovery from an acute coronary event--the role of psychological factors in Japanese vs North American patients

To determine whether specific psychological characteristics are associated with angina pectoris in clinically stable patients 1 to 6 months after recovery from an acute coronary event, a battery of tests was administered to 92 Japanese and 646 North American participants (22% females) in the Multicenter Study of Myocardial Ischemia. Of these 738 patients, 541 had originally suffered acute myocardial infarction, 188 had unstable angina, and 9 were admitted for other acute ischemic events. At the time of enrollment, an average of 2.7 months after the index event, 205 patients reported having had anginal symptoms during the preceding months. Compared to those who did not report angina, these patients scored higher on a modified Autonomic Perception Questionnaire (p = 0.04) and lower on the Internal Health Locus of Control Scale (p = 0.004). These differences were generalized across the Japanese and North American cohorts. These results indicate that in these patients, angina pectoris was associated with an increased awareness of a wide range of physical symptoms and a decreased sense of personal control over one's own health and prognosis.

Heart rate variability is independent of age, gender, and race in congestive heart failure with a recent acute exacerbation

Among normal adults, indexes of heart rate variability are affected by age, gender, and race. These effects are not seen among patients with congestive heart failure with a recent acute exacerbation, in whom indexes of heart rate variability are remarkably uniform and appear to be determined primarily by their recent cardiac failure.

Screening for depression in diabetes using the Beck Depression Inventory

OBJECTIVE

The purpose of this study was to determine the utility of the Beck Depression Inventory (BDI) as a screening tool for major depression in diabetes.

METHOD

One hundred seventy-two diabetic outpatients (insulin-dependent diabetes mellitus [IDDM] = 59, or non-insulin-dependent diabetes mellitus [NIDDM] = 113) being evaluated for a treatment trial were studied. BDI scores were calculated for the complete 21-item measure as well as for the cognitive (13 items) and somatic (eight items) symptom subgroups. The presence of depression was determined using the National Institute of Mental Health Diagnostic Interview Schedule in accordance with the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria. Receiver operating characteristic (ROC) analyses were used to evaluate the performance of the screening test in relation to the diagnostic standard.

RESULTS

Depressed subjects were effectively discriminated from nondepressed subjects by using the full 21-item BDI, the cognitive items alone, or the somatic items alone (p < .001 for each comparison), although the cognitive items were more effective than the somatic items (p < .0005). BDI total scores between 12 and 14 inclusive displayed the best balance between sensitivity (0.90-0.82) and specificity (0.84-0.89), but a cutoff score > or = 16 for the entire 21-item measure exhibited the best balance between sensitivity and positive predictive value when prediction values were extrapolated to a diabetic population with a depression prevalence rate of 20%. This cutoff score would capture > 70% of the patients diagnosed with major depression yet provide > 70% certainty that a person screening positive actually has the psychiatric disorder.

CONCLUSION

The BDI is an effective screening test for major depression in diabetic patients. Prospective studies are needed to confirm the test's precise performance characteristics in the general clinical setting.