Psychotic symptoms and apolipoprotein E genotypes in an elderly population

Cognitive decline and dementia risk in older adults with psychotic symptoms: a prospective cohort study

OBJECTIVES

To study the temporal association between psychotic symptoms with cognitive decline and incident dementia.

DESIGN

Population-based prospective cohort study.

SETTING

General population in England and Wales.

PARTICIPANTS

A subsample of 2,025 participants of the Medical Research Council Cognitive Function and Ageing Study, representing a study sample of 11,916 nondemented adults age 65 years or older.

MEASUREMENTS

Baseline presence of psychotic symptoms was assessed with the Geriatric Mental State. Cognitive decline (Cambridge Cognitive Examination) and incident dementia (Automated Geriatric Examination for Computer Assisted Taxonomy diagnosis) were evaluated at 2, 6, and 10 years from baseline.

RESULTS

A total of 330 participants reported baseline symptoms of paranoid delusions, misidentification, or hallucinations, estimated to represent 13.4% of the older general population without dementia. Psychotic symptoms were cross-sectionally associated with worse cognitive functioning, and individuals with psychotic symptoms displayed more rapid cognitive decline from baseline to a 6-year follow-up, especially in nonmemory functions, than people without such symptoms. They further carried an increased overall risk of later dementia (odds ratio = 2.76, 95% confidence interval = 1.75-4.36). The risk increment was observed independently of baseline cognition, depression, anxiety, and vascular risk factors, increased with increasing numbers of psychotic symptoms, and was highest in people age 65-74 years.

CONCLUSIONS

Older adults with psychotic symptoms are vulnerable to develop dementia and might be a promising target for indicated prevention strategies. Their neuropsychological functioning should be evaluated on a regular basis.

Missense substitutions associated with behavioural disturbances in Alzheimer's disease (AD)

Behavioural and psychological symptoms in dementia, or BPSD, occur in the majority of Alzheimer's disease (AD) patients. They are associated with considerable patient morbidity and greater care-giver stress. There is some evidence suggesting that BPSD have a genetic component and a large number of studies have examined the association of candidate genes with these symptoms. This review provides a comprehensive summary of all the published studies investigating the association of candidate gene missense substitutions with BPSD. Missense substitutions could potentially alter protein function or render the protein non-functional, resulting in phenotypic consequences. More than 80 studies investigating the association of 8 missense substitutions in 7 genes with BPSD were identified. However, results of these studies are contradictory and do not provide firm support for these associations. Larger studies and more systematic approaches will delineate the association of missense substitutions with behavioural symptoms in AD.

Apolipoprotein E genotypes and neuropsychiatric symptoms and syndromes in late-onset Alzheimer's disease

Neuropsychiatric symptoms (NPS) in dementia, previously denominated as behavioural and psychological symptoms of dementia, are often more distressing, impairing, and costly than cognitive symptoms, representing a major health burden for older adults. These symptoms are common features of Alzheimer's disease (AD), and are one of the major risk factors for institutionalization. There is a high prevalence of neuropsychiatric disturbances in patients with AD, including depression, anxiety, apathy, psychosis, aggression, and agitation. At present, the role of the apolipoprotein E (APOE) genotypes in the development of NPS or neuropsychiatric syndromes/endophenotypes in AD patients is unclear. In this article, we summarized the findings of the studies of NPS and neuropsychiatric syndromes in AD in relation to APOE genotypes, with special attention to the possible underlying mechanisms. While some studies failed to find a significant association between the APOE polymorphism and NPS in late-onset AD, other studies reported a significant association between the APOE ɛ4 allele and an increase in agitation/aggression, hallucinations, delusions, and late-life depression or anxiety. However, current cumulative evidence coming from the few existing longitudinal studies shows no association of APOE genotypes with NPS as a whole in AD. Some negative studies that focused on the distribution of APOE genotypes between AD patients with or without NPS further emphasized the importance of sub-grouping NPS in distinct neuropsychiatric syndromes. Explanations for the variable findings in the existing studies included differences in patient populations, differences in the assessment of neuropsychiatric symptomatology, possible lack of statistical power to detect associations in the negative studies, and small sample sizes generating false positives that cannot be consistently replicated. Finally, many reviewed studies were cross-sectional, whereas it would be of paramount importance to evaluate the risk for incident NPS in relation to the APOE genotype in prospectively followed cohorts of AD patients. In fact, identifying predisposing genetic risk factors may allow us to understand the pathophysiological features of neuropsychiatric syndromes or symptoms in AD, so optimizing possible therapeutic options.

The APOE polymorphism in Alzheimer's disease patients with neuropsychiatric symptoms and syndromes

BACKGROUND

Neuropsychiatric symptoms (NPS) are a common feature of Alzheimer's disease (AD), resulting in particular AD endophenotypes. The common AD genetic risk factor apolipoprotein E (APOE) has been suggested underlying these AD endophenotypes.

METHODS

APOE genotyping, a comprehensive geriatric assessment (CGA), and Neuropsychiatric Inventory were performed on 322 consecutive older patients. Patients were divided into three groups: AD with NPS (N = 93), AD without NPS (N = 108), and, as a control group, patients with no cognitive impairment (NoCI: N = 121). Patients with NPS were further sub-divided in four groups according to the European Alzheimer's Disease Consortium (EADC) classification of neuropsychiatric syndromes in AD: hyperactive, psychotic, affective, and apathetic.

RESULTS

AD patients with NPS showed a significantly higher grade of cognitive impairment, more severity stage of dementia, more disability in the activities of daily living (ADL), and the instrumental ADL than AD patients without NPS. As expected, an higher frequency of APOE ε3/ε4 genotype was observed in patients with AD, both with and without NPS, than patients with NoCI. No difference in the distribution of APOE genotypes was found between AD patients with vs. without NPS. However, in AD patients APOE ε4-carriers, there was an increased risk of affective [odds ratio (OR): 2.34, 95% confidence interval (CI): 1.19-4.58) and apathetic (OR: 2.24,95%CI: 1.19-4.22) syndromes.

CONCLUSIONS

These findings did not suggest a significant association between APOE polymorphism and presence of NPS in AD patients. In AD patients with NPS, however, APOE ε4-carrier status was associated with an increased risk of affective and apathetic syndromes.

Neuropsychiatric Symptoms, Endophenotypes, and Syndromes in Late-Onset Alzheimer's Disease: Focus on APOE Gene

Neuropsychiatric symptoms, previously denominated as behavioural and psychological symptoms of dementia, are common features of Alzheimer's disease (AD) and are one of the major risk factors for institutionalization. At present, the role of the apolipoprotein E (APOE) gene in the development of neuropsychiatric symptoms in AD patients is unclear. In this paper, we summarized the findings of the studies of neuropsychiatric symptoms and neuropsychiatric syndromes/endophenotypes in AD in relation to APOE genotypes, with special attention to the possible underlying mechanisms. While some studies failed to find a significant association between APOE and neuropsychiatric symptoms in late-onset AD, other studies reported a significant association between the APOE ε4 allele and an increase in agitation/aggression, hallucinations, delusions, and late-life depression or anxiety. Furthermore, some negative studies that focused on the distribution of APOE genotypes between AD patients with or without neuropsychiatric symptoms further emphasized the importance of subgrouping neuropsychiatric symptoms in distinct neuropsychiatric syndromes. Explanations for the variable findings in the existing studies included differences in patient populations, differences in the assessment of neuropsychiatric symptomatology, and possible lack of statistical power to detect associations in the negative studies.

Behavioural genetics of Alzheimer's disease: a comprehensive review

Behavioural and psychological symptoms of dementia (BPSD) are present in the course of the illness in up to 90% of patients with Alzheimer's disease (AD). They are the main source of caregiver burden and one of the major factors contributing to early institutionalization. The involvement of a genetic component in BPSD aetiology seems beyond controversy, though the exact significance of particular polymorphisms is uncertain in the majority of cases. Multiple genes have been assessed for their putative influence on BPSD risk. In this paper we review the behavioural genetics of AD, particularly the importance, with respect to BPSD risk, of genes coding for apolipoprotein E and proteins involved in the process of neurotransmission: serotonin receptors, serotonin transporter, COMT, MAO-A, tryptophan hydroxylase and dopamine receptors. A general conclusion is the striking inconsistency of the findings, unsurprising in the field of psychiatric genetics. The potential reasons for such discrepancy are exhaustively discussed.

Psychotic symptoms in a population-based sample of 85-year-old individuals with dementia

Psychotic symptoms are common in elderly persons with dementia. These symptoms affect a person's ability to function in daily life and put strain on the caregiver. Most studies focus on psychotic symptoms in clinical samples with Alzheimer disease (AD). Thus, their prevalence and relation with dementia subtype and severity in very old populations is unclear. We assessed a representative sample of 85-year-old individuals living in Gothenburg, Sweden (n = 494) using neuropsychiatric examinations, key informant interviews, and medical record reviews; 147 had dementia. Dementia and its severity were diagnosed in accordance with Diagnostic and Statistical Manual of Mental Disorders (Third Edition, Revision [DSM-III-R]) criteria. Alzheimer disease according to the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria was diagnosed in 64 persons and vascular dementia (VaD) according to Erkinjuntti criteria was observed in 69. Fourteen had dementia due to other causes. Psychotic symptoms were classified according to DSM-III-R. The prevalence of psychotic symptoms in this very old population was 36% among AD cases compared to 54% in VaD cases (P = .04). Proportions with psychotic symptoms increased with increasing dementia severity in individuals with AD. No such association could be shown in those with VaD. This finding of a high proportion of psychotic symptoms also in individuals with mild severity of VaD should alert health professionals to evaluate dementia in very old patients who present with hallucinations or delusions.

The effect of the apolipoprotein E gene polymorphisms and haplotypes on behavioural and psychological symptoms in probable Alzheimer's disease

BACKGROUND

Patients with Alzheimer's disease and dementia commonly suffer from behavioural and psychological symptoms of dementia (BPSD). A genetic component to BPSD development in Alzheimer's disease has been demonstrated. Several studies have investigated whether the exon 4 epsilon2/epsilon3/epsilon4 haplotype of the apolipoprotein E (APOE) gene is associated with BPSD, with variable results.

OBJECTIVE

We investigated the exon 4 polymorphisms and extended this study to include promoter polymorphisms and the resultant haplotypes across the gene.

METHODS

Our large independent cohort of 388 patients with longitudinal measures of BPSD assessed by the Neuropsychiatric Inventory was used to analyse whether any of these variants were associated with the presence of BPSD.

RESULTS

We revealed several significant relationships before correction for multiple testing. The exon 4 haplotype was associated with hallucinations and anxiety, A-491T with irritability, T-427C with agitation/aggression and appetite disturbances, and T-219C with depression. Haplotype analyses of all variants did not reveal any statistically significant findings.

CONCLUSIONS

Our data and a review of previous studies showed a diversity of relationships, suggesting that these findings might be due to chance and so collectively do not support a role for the APOE gene in BPSD.

Regional cerebral metabolism in early Alzheimer's disease with clinically significant apathy or depression

BACKGROUND

Alzheimer's disease (AD) is clinically characterized by cognitive impairment and behavioral disturbances. The aim of the study was to identify regional alterations in brain function associated with neuropsychiatric symptoms in early AD.

METHODS

Patients underwent measures of cerebral glucose metabolism applying positron emission tomography (PET) and (18)F-fluorodeoxyglucose. Neuropsychiatric symptoms were assessed using the Neuropsychiatric Inventory (NPI). Positron emission tomography images of patients suffering a neuropsychiatric symptom of clinical significance (NPI subscore for a specific item >/=4 points) were compared with the images of patients without the specific symptom under study (NPI subscore for a specific item = 0 points).

RESULTS

A total of 53 patients with AD (Mini-Mental State Examination [MMSE] 22.5 +/- 2.94 points) entered the study. Of all symptoms, apathy and depression were most frequently encountered. The patient group with apathy (n = 17) revealed significant decreases in left orbitofrontal regions when compared with patients free of apathy. Depression of clinical significance (n = 10) was associated with hypometabolism in dorsolateral prefrontal regions.

CONCLUSIONS

These findings support the notion that different functional circuits underlie apathy and depression in early AD.

Serotoninergic Polymorphisms (5-HTTLPR and 5-HT2A): Association Studies with Psychosis in Alzheimer Disease

Patients with Alzheimer disease (AD) often exhibit psychotic symptoms associated with cognitive impairment. A few association studies have been carried out to determine if the serotonin transporter and receptor genes are potential risk factors for AD and/or associated psychopathology. The aim of this study was to investigate the association of a serotonin transporter gene-linked polymorphic region (5-HTTLPR) and the 5-HT2A receptor T102C polymorphism with the risk of developing dementia and/or psychotic symptoms in a group of sporadic AD patients from Italy. No significant differences in the distribution of allele and genotype frequencies of 5-HTTLPR and 5-HT2A T102C were found between patient and control groups. However, a significant association between the C102/C102 5-HT2A genotype and psychotic symptoms (p < 0.001) was observed. Our data strongly confirm results from previous studies suggesting that the C102 allele of the 5-HT2A receptor is associated with the occurrence of psychotic symptoms in AD. On the contrary, the serotonin transporter does not appear to be a major susceptibility factor in the pathophysiology of the disease.

HSP70-2 (HSPA1B) is associated with noncognitive symptoms in late-onset Alzheimer's disease

Neuropsychiatric manifestations are common in Alzheimer's disease (AD) and their phenotypic expression might be related to physiopathological and genetic causes. Multiple studies have implicated oxidative stress to the pathogenesis and possible etiology of AD. One of the mechanisms to protect cells from oxidative stress is the expression of heat-shock proteins (HSP). HSPA1B (alternatively known as HSP70-2) has been related to AD pathophysiology. In the present analysis, 77 AD patients were classified according to their cognitive status with the Neuropsychiatric Inventory and were genotyped for an insertion/deletion (A1/A2) polymorphism. The A2 allele conferred a significant increase of psychiatric morbidity in an allele-dose manner (P < .05). This pattern can be attributed to all AD stages and the severity of the behavioral disturbances was higher for those patients carrying one or two A2 alleles. These results indicate a possible association between the A2 allele and an overexpression of noncognitive symptoms in AD.

Psychotic symptoms in Alzheimer disease: evidence for a distinct phenotype

Though efforts to identify the genetic etiology of Alzheimer disease (AD) have made substantial progress, to date only some of the genes contributing to AD risk have been identified. Utilization of more etiologically homogeneous subphenotypes represents one strategy to facilitate the identification of novel risk genes in complex disorders. In this review, we evaluate the hypothesis that psychotic symptoms, such as delusions and hallucinations, define a suitable subphenotype in AD patients for gene-mapping efforts. Psychotic symptoms occur in 40-60% of patients with AD and are associated with more severe cognitive deficits and a more rapidly deteriorating course. The presence of psychotic symptoms in AD confers increased risk of similar symptoms to affected siblings. Candidate gene association analyses and initial linkage analysis have yielded significant results. We discuss possible genetic models of psychotic symptoms in AD, and suggest strategies for further investigation. Identification of such genetic factors may facilitate gene-mapping studies for both AD and idiopathic psychoses.

Behavioural pathology in Alzheimer's disease with special reference to apolipoprotein E genotype

The aim of this study was to define the co-occurrence of behavioural symptoms and Alzheimer's disease (AD) in relation to apolipoprotein E (APOE) genotype. Probable AD patients from the Alzheimer's Day Clinic (n = 139) were assessed with the 'Behavioural Pathology in Alzheimer's Disease' rating scale, and their APOE genotype was determined. This study demonstrated no relationship between presence of the APOE epsilon4 allele and any of the behavioural symptoms assessed, including delusions, hallucinations, depression, activity disturbances, aggressiveness and anxiety. Activity disturbances, delusions, hallucinations and aggressiveness paralleled the severity of AD, increasing in frequency with the severity of the dementia. The prevalence of delusions, hallucinations, aggressiveness and depression were found to be associated with lower levels of education.

Apolipoprotein E and alpha-1-antichymotrypsin genotypes do not predict time to psychosis in Alzheimer's disease

Psychotic symptoms occurring in Alzheimer's disease (AD + psychosis, AD + P) are a marker for a more rapidly deteriorating phenotype. We have developed a polygenic model of AD + P risk, conditioned on the presence of AD. Whether risk genes for AD itself contribute to AD + P risk is not established, although our model predicts they will not. The most important identified genetic determinant of sporadic, late-onset AD is the apolipoprotein E epsilon 4 allele (APOE4). The effect of APOE4 on AD phenotype is to reduce the age of onset of AD. Prior studies examining the association of APOE4 with AD + P have reported conflicting results. However, no prior studies have examined if APOE4 reduces time to onset of psychosis in AD. The objective of this study was to examine the effect of APOE4 and alpha1-antichymotrypsin/AA (ACT/AA) genotypes on time to psychosis onset in subjects with AD. A longitudinal study of psychosis incidence in 316 subjects with AD with no history of current or prior psychotic symptoms at entry was undertaken. APOE and ACT genotyping was conducted per established protocols. Data were analyzed by survival analysis and Cox proportional hazards models. There were no significant associations of APOE or ACT genotypes with time to psychosis onset and no significant interaction of these genotypes with time to psychosis onset. There remained no significant associations after covarying for age, age of AD onset, degree of cognitive impairment, gender, race, and education. This is the first study to examine the genetic prediction of psychosis onset in AD. The findings support the hypothesis that these two genetic determinants of AD risk do not contribute to the risk of development of psychotic symptoms in AD.

Apolipoprotein E among Korean Alzheimer's disease patients in community-dwelling and hospitalized elderly samples

This study evaluated the association of the apolipoprotein E epsilon4 allele (epsilon4) with Alzheimer's disease (AD) and investigated the relationships of epsilon4 with clinical characteristics of AD in both community-dwelling and hospitalized Korean elderly populations. The apolipoprotein E genotypes were compared between a group of 52 community-dwelling patients with AD (C-AD), a group of 52 hospitalized patients with AD (H-AD) and a group of 52 healthy controls matched to C-AD. Clinical characteristics and scores on several assessment scales were compared between C-AD and H-AD as well as between two subgroups within each AD group: those with epsilon4 and those without epsilon4. For H-AD, the assessment scales were administered again 6 months later, and the temporal course of AD was compared between the subgroups. The frequency of epsilon4 was significantly higher in both AD groups than in controls. Between C-AD and H-AD, no differences were found in epsilon4 frequency, while symptoms of dementia were significantly severer in H-AD than in C-AD. Within each AD group, no differences were observed in terms of clinical characteristics and scores on the assessment scales between the subgroups. Furthermore, the subgroups of H-AD showed no difference in the rate of progression. In conclusion, there was a significant association of epsilon4 with AD. However, no relationships were found between epsilon4 and clinical characteristics in either C-AD or H-AD. Furthermore, the rate of progression did not vary with respect to the presence or absence of epsilon4 in H-AD. The severer symptoms observed in the hospitalized sample than in those at large might be explained by factors other than the impact of epsilon4.

Association between the APOE genotype and psychopathologic symptoms in Alzheimer's disease

BACKGROUND

Psychiatric symptoms occur frequently in the course of AD, are a frequent contributor to institutionalization, predict cognitive decline and death, and often require treatment with psychotropic medications. Previous studies investigating the association between APOE genotype and psychiatric symptomatology in AD have reported contradictory results.

OBJECTIVE

To determine whether APOE genotype predicts incident psychiatric symptomatology in patients with AD.

METHODS

Eighty-seven patients with AD at early stages and no psychiatric history were followed semiannually for up to 9.3 years (mean 5.5 years) for development of delusions, illusions, hallucinations, behavioral symptoms, and depression. Cox proportional hazards models were used to examine the relative risk for incident psychiatric symptomatology (outcome) in relation to APOE genotype (predictor).

RESULTS

The presence of one epsilon4 allele carried a 2.5-fold risk, whereas the presence of two epsilon4 alleles carried a 5.6-fold risk for development of delusions. The associations remained significant even when age, ethnicity, sex, education, duration of disease, and cognitive and functional performance were controlled for. The presence of two epsilon4 alleles was associated with reduced risk for developing hallucinations in the adjusted analysis only. No significant associations were detected between APOE genotype and the incidence of illusions, behavioral symptoms, or depression.

CONCLUSION

The presence of one or more epsilon4 alleles is a significant predictor for the incidence of delusions in the course of AD.

Apolipoprotein E regulatory region genotype in schizophrenia

Clinical observations indicate that a proportion of patients with schizophrenia experience cognitive impairment, which suggests that a neurodegenerative basis might be involved in the etiology of schizophrenia. Apolipoprotein E (ApoE), which has been confirmed to be genetically associated with Alzheimer's disease, is thus highlighted as a candidate gene for schizophrenia. Recently, novel functional polymorphisms in the ApoE transcriptional regulatory region have been found. To investigate whether these polymorphisms are associated with the risk of schizophrenia, we genotyped 144 patients with schizophrenia and 134 controls for two polymorphisms (-491A/T and -219G/T). No significant positive associations between both polymorphisms and schizophrenia were observed. Our findings exclude the regulatory region of the ApoE gene as a locus that might confer increased susceptibility to schizophrenia.