Magnetic resonance imaging correlates of psychosis in Alzheimer's disease

Neuropsychiatric symptoms and brain morphology in patients with mild cognitive impairment and Alzheimer's disease with dementia

We present associations between neuropsychiatric symptoms (NPS) and brain morphology in a large sample of patients with mild cognitive impairment (MCI) and Alzheimer's disease with dementia (AD dementia).Several studies assessed NPS factor structure in MCI and AD dementia, but we know of no study that tested for associations between NPS factors and brain morphology. The use of factor scores increases parsimony and power. For transparency, we performed an additional analysis with selected Neuropsychiatric Inventory - Questionnaire (NPI-Q) items. Including regional cortical thickness, cortical and subcortical volumes, we examined associations between NPS and brain morphology across the whole brain in an unbiased fashion. We reported both statistical significance and effect sizes, using linear models adjusted for multiple comparisons by false discovery rate (FDR). Moreover, we included an interaction term for diagnosis and could thereby compare associations of NPS and brain morphology between MCI and AD dementia.We found an association between the factor elation and thicker right anterior cingulate cortex across MCI and AD dementia. Associations between the factors depression to thickness of the banks of the left superior temporal sulcus and psychosis to the left post-central volume depended on diagnosis: in MCI these associations were positive, in AD dementia negative.Our findings indicate that NPS in MCI and AD dementia are not exclusively associated with atrophy and support previous findings of associations between NPS and mainly frontotemporal brain structures.

OBJECTIVES

Neuropsychiatric symptoms (NPS) are common in mild cognitive impairment (MCI) and Alzheimer’s disease with dementia (AD dementia), but their brain structural correlates are unknown. We tested for associations between NPS and MRI-based cortical and subcortical morphometry in patients with MCI and AD dementia.

DESIGN

Cross-sectional.

SETTINGS

Conducted in Norway.

PARTICIPANTS

Patients with MCI (n = 102) and AD dementia (n = 133) from the Memory Clinic and the Geriatric Psychiatry Unit at Oslo University Hospital.

MEASUREMENTS

Neuropsychiatric Inventory – Questionnaire (NPI-Q) severity indices were reduced using principal component analysis (PCA) and tested for associations with 170 MRI features using linear models and false discovery rate (FDR) adjustment. We also tested for differences between groups. For transparency, we added analyses with selected NPI-Q items.

RESULTS

PCA revealed four factors: elation, psychosis, depression, and motor behavior.FDR adjustment revealed a significant positive association (B = 0.20, pFDR < 0.005) between elation and thickness of the right caudal anterior cingulate cortex (ACC) across groups, and significant interactions between diagnosis and psychosis (B = −0.48, pFDR < 0.0010) on the left post-central volume and between diagnosis and depression (B = −0.40, pFDR < 0.005) on the thickness of the banks of the left superior temporal sulcus. Associations of apathy, anxiety, and nighttime behavior to the left temporal lobe were replicated.

CONCLUSIONS

The positive association between elation and ACC thickness suggests that mechanisms other than atrophy underly elation. Interactions between diagnosis and NPS on MRI features suggest different mechanisms of NPS in our MCI and AD dementia samples. The results contribute to a better understanding of NPS brain mechanisms in MCI and AD dementia.

Psychosis and Clinical Outcomes in Alzheimer Disease: A Longitudinal Study

OBJECTIVE

Psychotic symptoms are a common feature in Alzheimer disease (AD), occurring in approximately 40% of patients. These symptoms are associated with worse clinical outcomes. Comparatively little research, however, has distinguished delusions and hallucinations, which may have distinct clinical, neuropathological, and genetic correlates. To address this, the current study examined the clinical outcomes associated with delusions and hallucinations in AD.

DESIGN

Three-year observational study.

SETTING

Nine memory clinics in Australia.

PARTICIPANTS

A total of 445 patients with AD.

MEASUREMENTS

Measures of neuropsychiatric symptoms, dementia severity, cognition, function, caregiver burden, and medication use were completed annually for 3 years with additional assessments at 3 months and 6 months in the first year. Mortality data were obtained from state registries approximately 5 years after the study.

RESULTS

Of 445 patients, 102 (22.9%) developed only delusions, 39 (8.8%) developed only hallucinations, and 84 (18.9%) developed both symptoms. Delusions and hallucinations were both associated with greater dementia severity, poorer cognition and function, higher levels of other neuropsychiatric symptoms, and greater caregiver burden. The presence of both symptoms was associated with worse outcomes than only one of these symptoms. Delusions, both by themselves and in combination with hallucinations, predicted institutionalization. Antipsychotic medication use predicted mortality.

CONCLUSIONS

Delusions and hallucinations independently and in combination are associated with poor clinical outcomes. The findings highlight the challenges managing these patients, particularly given the high levels of caregiver burden associated with psychotic symptoms and the likely mortality arising from antipsychotic medication.

Decreased gray matter volume is associated with the subtypes of psychotic symptoms in patients with antipsychotic-naïve mild or moderate Alzheimer's disease: A voxel-based morphometry study

The purpose of this study was to investigate the association between brain regional gray matter volume and two subtypes of psychotic symptoms, namely paranoid and misidentification subtypes, in antipsychotic-naïve mild or moderate Alzheimer's disease (AD) patients. Forty AD patients with psychotic symptoms and 25 AD patients without psychotic symptoms were assessed for cognitive and functional impairment. Presence and subtype of psychotic symptoms were assessed by using the delusion and hallucination subscale of the Korean Neuropsychiatric Inventory (K-NPI). Structural MRI images were acquired on a 3 T scanner, and were analyzed using voxel-based morphometry (VBM) for automated analysis. The misidentification subtype is associated with more severe gray matter atrophy, and paranoid subtype is associated with less severe gray matter atrophy compared to non-psychosis group. These results suggest that the misidentification, the paranoid subtype and the non-psychosis group have a distinct neural correlation.

Clinicopathological correlation of psychosis and brain vascular changes in Alzheimer's disease

Psychosis is common in Alzheimer’s disease (AD). However, studies on neuropathology in vascular etiology contributing to psychosis in AD is lacking to date. The aim of this study was to investigate neuropathological vascular related changes in Alzheimer’s disease with psychosis. Data of patients with AD from the National Alzheimer’s Coordinating Center between 2005 to September 2013 was accessed and reviewed. Presence of psychosis was determined based on Neuropsychiatric Inventory Questionnaire taken from the last visit within one year prior to death, and patients were divided into psychosis positive and negative group. Comparison of clinical details and neuropathological vascular changes between the groups was performed using Wilcoxon rank sum test and Chi-square/ Fisher’s exact test. Significant variables were further included in a multivariate logistic model. Overall, 145 patients was included. Of these, 50 patients were psychosis positive. Presence of one or more cortical microinfarcts and moderate to severe arteriosclerosis was found to be positively associated with psychosis. Our results suggest vascular changes correlate with psychosis in Alzheimer’s disease.

Right anterior insula: core region of hallucinations in cognitive neurodegenerative diseases

Objectives

We investigated the neural basis of hallucinations Alzheimer's disease (AD) by applying voxel-based morphometry (VBM) to anatomical and functional data from the AD Neuroimaging Initiative.

Methods

AD patients with hallucinations, based on the Neuropsychiatric Inventory (NPI-Q) (AD-hallu group; n = 39), were compared to AD patients without hallucinations matched for age, sex, educational level, handedness and MMSE (AD-c group; n = 39). Focal brain volume on MRI was analyzed and compared between the two groups according to the VBM method. We also performed voxel-level correlations between brain volume and hallucinations intensity. A similar paradigm was used for the PET analysis. “Core regions” (i.e. regions identified in both MRI and PET analyses, simply done by retaining the clusters obtained from the two analyses that are overlapping) were then determined.

Results

Regions with relative atrophy in association with hallucinations were: anterior part of the right insula, left superior frontal gyrus and lingual gyri. Regions with relative hypometabolism in association with hallucinations were a large right ventral and dorsolateral prefrontal area. "Core region" in association with hallucinations was the right anterior part of the insula. Correlations between intensity of hallucinations and brain volume were found in the right anterior insula, precentral gyrus, superior temporal gyrus, and left precuneus. Correlations between intensity of hallucinations and brain hypometabolism were found in the left midcingulate gyrus. We checked the neuropathological status and we found that the 4 patients autopsied in the AD-hallu group had the mixed pathology AD and Dementia with Lewy bodies (DLB).

Conclusion

Neural basis of hallucinations in cognitive neurodegenerative diseases (AD or AD and DLB) include a right predominant anterior-posterior network, and the anterior insula as the core region. This study is coherent with the top-down/bottom-up hypotheses on hallucinations but also hypotheses of the key involvement of the anterior insula in hallucinations in cognitive neurodegenerative diseases.

Origins of delusions in Alzheimer's disease

Research over the past two decades supports a shared aetiology for delusions in Alzheimer's disease (AD) and schizophrenia. Functional networks involved in salience attribution and belief evaluation have been implicated in the two conditions, and striatal D2/3 receptors are increased to a comparable extent. Executive/frontal deficits are common to both disorders and predict emergent symptoms. Putative risk genes for schizophrenia, which may modify the AD process, have been more strongly implicated in delusions than those directly linked with late-onset AD. Phenotypic correlates of delusions in AD may be dependent upon delusional subtype. Persecutory delusions occur early in the disease and are associated with neurochemical and neuropathological changes in frontostriatal circuits. In contrast, misidentification delusions are associated with greater global cognitive deficits and advanced limbic pathology. It is unclear whether the two subtypes are phenomenologically and biologically distinct or are part of a continuum, in which misidentification delusions manifest increasingly as the pathological process extends. This has treatment implications, particularly if they are found to have discrete chemical and/or pathological markers.

The hallucinating brain: A review of structural and functional neuroimaging studies of hallucinations

Hallucinations remains one of the most intriguing phenomena in psychopathology. In the past two decades the advent of neuroimaging techniques have allowed researchers to investigate what is happening in the brain of those who experience hallucinations. In this article we review both structural and functional neuroimaging studies of patients with auditory and visual hallucinations as well as a small number of studies that have assessed cognitive processes associated with hallucinations in healthy volunteers. The current literature suggests that in addition to secondary (and occasionally primary) sensory cortices, dysfunction in prefrontal premotor, cingulate, subcortical and cerebellar regions also seem to contribute to hallucinatory experiences. Based on the findings of these studies we tentatively propose a neurocognitive model in which both bottom-up and top-down processes interact to produce these erroneous percepts. Finally, directions for future work are discussed.

The occipital white matter lesions in Alzheimer's disease patients with visual hallucinations

PURPOSE

Investigators have suggested that lesions responsible for visual hallucinations (VHs) are situated in the visual association cortex. The aim of this study was to assess the relationship between occipital white matter lesions and VHs in Alzheimer's disease (AD) patients.

METHODS

AD patients with a history of VHs (AD+VH) and those without (AD-VH) were retrospectively studied. The two groups of patients were matched by sex and mental state. All subjects underwent brain magnetic resonance image (MRI) scans. The periventricular hyperintensities (PVHs) and deep white matter hyperintensities (DWHs) on MRIs were rated by two raters using a semiquantitative scoring method (0=absent; 6=confluent).

RESULTS

Five AD+VH patients and five AD-VH patients were enrolled into this study. The occipital PVH score was higher in the AD+VH patients than in the AD-VH patients. The occipital DWH score was zero in both groups.

CONCLUSION

The presence of VHs in AD was associated with increased occipital PVHs and an absence of occipital DWHs on brain MRIs, implying that structural lesions in the geniculocalcarine region and preserved subcortical connections with visual association areas are involved in the genesis of VHs in AD.

Neuroimaging of hallucinations: a review of the literature

While hallucinations have been described for over two millennia, their cause remains unclear. Brain-based models suggest that abnormal cerebral excitation and a lack of normal cerebral inhibition may play primary roles, but evaluation of these hypotheses has been hampered by difficulty in studying the hallucinatory state. Recent advances in neuroimaging have provided researchers with tools to study a variety of mental states, including hallucinations. We review the literature regarding the structural and functional neural correlates of hallucinations. Despite small sample sizes and methodological differences, several studies describe similar results: hallucinations are associated with sensory modality-specific activation in cerebral areas involved in normal sensory processing. Furthermore, neural activation may be specifically related to distinct phenomenological features of the hallucinatory experience. Further work is needed to better understand the neural basis of hallucinations.

White matter lesions on magnetic resonance imaging in dementia with Lewy bodies, Alzheimer's disease, vascular dementia, and normal aging

OBJECTIVES

Alzheimer's disease and vascular dementia are associated with an increase in changes in white matter on MRI. The aims were to investigate whether white matter changes also occur in dementia with Lewy bodies and to examine the relation between white matter lesions and the cognitive and non-cognitive features of dementia with Lewy bodies, Alzheimer's disease, and vascular dementia.

METHODS

Proton density and T2 weighted images were obtained on a 1.0 Tesla MRI scanner in patients with dementia with Lewy bodies (consensus criteria; n=27, mean age=75.9 years), Alzheimer's disease (NINCDS/ADRDA; n=28, mean age=77.4 years), vascular dementia (NINDS/AIREN; n=25, mean age=76.8 years), and normal controls (n=26, mean age=76.2 years). Cognitive function, depressive symptoms, and psychotic features were assessed using a standardised protocol. Periventricular hyperintensities (PVHs), white matter hyperintensities (WMHs) and basal ganglia hyperintensities (BGHs) were visually rated blind to diagnosis using a semiquantitative scale.

RESULTS

Periventricular hyperintensities were positively correlated with age and were more severe in all dementia groups than controls. Total deep hyperintensities scores (WMHs plus BGHs) were significantly higher in all dementia groups than controls and higher in patients with vascular dementia than those with dementia with Lewy bodies or Alzheimer's disease. In all patients with dementia, frontal WMHs were associated with higher depression scores and occipital WMHs were associated with an absence of visual hallucinations and delusions.

CONCLUSION

In common with Alzheimer's disease and vascular dementia, PVHs and WMHs were significantly more extensive in dementia with Lewy bodies than in controls. This overlap between different dementias may reflect shared pathological mechanisms. The link between frontal WMHs and depression and the absence of occipital WMHs and psychotic symptoms has important implications for understanding the neurobiological basis of these symptoms.

Age and psychosis in degenerative dementia

Among psychiatric inpatients with primary degenerative dementia, those with psychotic symptoms (N = 20) were older than those without (N = 20) (t = 3.48; p < 0.001). Persecutory delusions were the most frequent psychotic phenomena. Duration of dementia overlapped, but scores on the Global Deterioration Scale and the Cornell Scale for Depression in Dementia were lower in the psychotic group after correcting for age. The limited literature concerning demographic and clinical correlates of psychosis in dementia is reviewed; the age difference noted is consistent with two other reports.