Increased retention of tau PET ligand [18F]-AV1451 in Alzheimer's Disease Psychosis

Psychosis in Alzheimer's disease (AD) represents a distinct disease subtype with a more rapid progression of illness evidenced by an increased velocity of cognitive decline and a hastened mortality. Previous biomarker and post-mortem studies have implicated tau neuropathology as a possible mediator of the accelerated decline in AD psychosis. Tau positron emission tomography (PET) neuroimaging provides the opportunity to evaluate tau pathology in-vivo, so that clinical symptomatology can be correlated with disease pathology. [¹⁸F]-AV1451 (Flortaucipir) is a PET ligand with high affinity for insoluble paired-helical filaments (PHFs) of hyperphosphorylated tau. In order to determine whether the development of psychosis and worsened prognosis in AD is associated with an increased burden of tau pathology that can be identified with tau imaging, we identified subjects within the Alzheimer's disease neuroimaging initiative (ADNI) who had [¹⁸F]-AV1451 imaging at baseline and became psychotic over the course of the study (N = 17) and matched them 1:3 for gender, age, and education to subjects who had [¹⁸F]-AV1451 imaging at baseline and did not become psychotic (N = 50). We compared baseline [¹⁸F]-AV1451 retention, in addition to cognitive and functional baseline and longitudinal change, in those who became psychotic over the course of participation in ADNI with those who did not. Results suggest that increases in tau pathology in frontal, medial temporal, and occipital cortices, visualized with [¹⁸F]-AV1451 binding, are associated with psychosis and a more rapid cognitive and functional decline.

Development of an UPSA Short Form for Use in Longitudinal Studies in the Early Alzheimer's Disease Spectrum

BACKGROUND

In individuals with only mild or very mild cognitive attenuations (i.e., so-called pre-clinical AD), performance-based measures of function may be superior to informant-based measures because of increased sensitivity, greater reliability, and fewer ceiling effects.

OBJECTIVE

We sought to determine if a performance-based measure of everyday function would demonstrate adequate psychometric properties and validity in the context of serial assessment over a one-year period in patients with Mild Cognitive Impairment (MCI) and early stage Alzheimer's disease (AD).

DESIGN

Participants were assessed with the performance-based measure at baseline, six weeks, and one year.

SETTING

A specialized center for the assessment and treatment of AD.

PARTICIPANTS

Three groups of subjects participated: a healthy subjects (HS) older cognitively intact group (N=43), an MCI group (N=20), and an AD group (N=26).

MEASUREMENTS

A three subtest short form of the UCSD Performance-Based Skills Assessment (UPSA) (called the UPSA-3) was the measure of interest. It consisted of the Communication, Planning, and Finance subtests.

RESULTS

Mixed model repeated measures were used to assess performance over time. Large group effects were present (HS>MCI>AD). Additionally, the AD and MCI groups demonstrated declines over one year, while the HS group remained stable (group x time interaction p=.11). The MCI/AD group demonstrated adequate test-retest reliability and did not demonstrate ceiling or floor effects.

CONCLUSION

Our data indicate that the UPSA-3 is suitable for clinical trials in that it has adequate ecological coverage and reasonable psychometric properties, and perhaps most importantly, demonstrates validity in serial assessments.

Brain structural changes in schizoaffective disorder compared to schizophrenia and bipolar disorder

OBJECTIVE

Brain structural changes in schizoaffective disorder, and how far they resemble those seen in schizophrenia and bipolar disorder, have only been studied to a limited extent.

METHOD

Forty-five patients meeting DSM-IV and RDC criteria for schizoaffective disorder, groups of patients with 45 matched schizophrenia and bipolar disorder, and 45 matched healthy controls were examined using voxel-based morphometry (VBM).

RESULTS

Analyses comparing each patient group with the healthy control subjects found that the patients with schizoaffective disorder and the patients with schizophrenia showed widespread and overlapping areas of significant volume reduction, but the patients with bipolar disorder did not. A subsequent analysis compared the combined group of patients with the controls followed by extraction of clusters. In regions where the patients differed significantly from the controls, no significant differences in mean volume between patients with schizoaffective disorder and patients with schizophrenia in any of five regions of volume reduction were found, but mean volumes in the patients with bipolar disorder were significantly smaller in three of five.

CONCLUSION

The findings provide evidence that, in terms of structural gray matter brain abnormality, schizoaffective disorder resembles schizophrenia more than bipolar disorder.

Executive dysfunction and memory impairment in schizoaffective disorder: a comparison with bipolar disorder, schizophrenia and healthy controls

BACKGROUND

Deficits in memory and executive performance are well-established features of bipolar disorder and schizophrenia. By contrast, data on cognitive impairment in schizoaffective disorder are scarce and the findings are conflicting.

METHOD

We used the Wechsler Memory Scale (WMS-III) and the Behavioural Assessment of the Dysexecutive Syndrome (BADS) to test memory and executive function in 45 schizophrenic patients, 26 schizomanic patients and 51 manic bipolar patients in comparison to 65 healthy controls. The patients were tested when acutely ill.

RESULTS

All three patient groups performed significantly more poorly than the controls on global measures of memory and executive functioning, but there were no differences among the patient groups. There were few differences in memory and executive function subtest scores within the patient groups. There were no differences in any test scores between manic patients with and without psychotic symptoms.

CONCLUSIONS

Schizophrenic, schizomanic and manic patients show a broadly similar degree of executive and memory deficits in the acute phase of illness. Our results do not support a categorical differentiation across different psychotic categories with regard to neuropsychological deficits.

First-episode psychosis is characterized by failure of deactivation but not by hypo- or hyperfrontality

BACKGROUND

It is not known whether first-episode psychosis is characterized by the same prefrontal cortex functional imaging abnormalities as chronic schizophrenia.

METHOD

Thirty patients with a first episode of non-affective functional psychosis and 28 healthy controls underwent functional magnetic resonance imaging (fMRI) during performance of the n-back working memory task. Voxel-based analyses of brain activations and deactivations were carried out and compared between groups. The connectivity of regions of significant difference between the patients and controls was also examined.

RESULTS

The first-episode patients did not show significant prefrontal hypo- or hyperactivation compared to controls. However, they showed failure of deactivation in the medial frontal cortex. This area showed high levels of connectivity with the posterior cingulate gyrus/precuneus and parts of the parietal cortex bilaterally. Failure of deactivation was significantly greater in first-episode patients who had or went on to acquire a DSM-IV diagnosis of schizophrenia than in those who did not, and in those who met RDC criteria for schizophrenia compared to those who did not.

CONCLUSIONS

First-episode psychosis is not characterized by hypo- or hyperfrontality but instead by a failure of deactivation in the medial frontal cortex. The location and connectivity of this area suggest that it is part of the default mode network. The failure of deactivation seems to be particularly marked in first-episode patients who have, or progress to, schizophrenia.

Awareness of cognitive impairment in schizophrenia and its relationship to insight into illness

BACKGROUND

Patients with schizophrenia have been found to show unawareness of cognitive impairment. However, its frequency and its relationship to lack of insight into illness are uncertain.

METHOD

Forty-two patients with chronic schizophrenia were given tests of executive function and memory. Awareness of cognitive impairment was measured by means of discrepancy scores--differences between patient and psychologist ratings of memory and frontal/executive failures in daily life. Insight into illness was assessed using the Scale to Assess Unawareness of Mental Disorder (SUMD).

RESULTS

A majority of the patients were found to underestimate their cognitive impairment; however, some overestimated it. Unawareness of cognitive impairment and lack of clinical insight loaded on different factors in a factor analysis, but these two factors were themselves correlated.

CONCLUSIONS

The findings suggest that both unawareness and overestimation of cognitive impairment characterise patients with schizophrenia, although the former is more common. Awareness of cognitive impairment occurs independently of insight into illness at the clinical level, although the two phenomena may be linked at a deeper level.

COMT Val158Met polymorphism in relation to activation and de-activation in the prefrontal cortex: A study in patients with schizophrenia and healthy subjects

The Val158Met polymorphism in the COMT gene has been found to be associated with differences in brain activation in both healthy subjects and patients with schizophrenia. The predominant finding has been increased prefrontal activation associated with the Val allele; however, genotype-related de-activations have not been studied. In this study 42 schizophrenia patients and 31 controls underwent fMRI while performing the n-back task. Brain differences related to presence/absence of disease and presence/absence of the Val/Val genotype were examined. Both disease and Val/Val genotype were associated with failure of de-activation in a cluster centred in the medial prefrontal cortex. There was no interaction between disease and genotype at this location, but clusters where there were significant interactions emerged in the right prefrontal cortex and left temporal/parietal cortex. These findings suggest that Val158Met polymorphism influences task-related de-activations in the default mode network in both healthy subjects and schizophrenia patients to an equivalent extent. However the Val158Met polymorphism also has disease-specific effects on DLPFC activation in schizophrenia.