Temporal lobe asymmetry in patients with Alzheimer's disease with delusions

Università degli Studi di Brescia, Brescia, Lombardy, Italy
Journal of Neurology Neurosurgery & Psychiatry (Impact Factor: 6.81). 09/2000; 69(2):187-91. DOI: 10.1136/jnnp.69.2.187
Source: PubMed

ABSTRACT To test the hypothesis that delusions are associated with asymmetric involvement of the temporal lobe regions in Alzheimer's disease.
Temporal lobe atrophy was assessed with a linear measure of width of the temporal horn (WTH) taken from CT films. Temporal asymmetry was computed as the right/left (R/L) ratio of the WTH in 22 non-delusional and 19 delusional patients with Alzheimer's disease. Delusional patients had paranoid delusions (of theft, jealousy, persecution). None of the patients had misidentifications or other delusions of non-paranoid content.
The R/L ratio indicated symmetric temporal horn size in the non-delusional (mean 1. 05 (SD 0.20), and right greater than left temporal horn in the delusional patients (mean 1.30, (SD 0.46); t=2.27, df=39, p=0.03). When patients were stratified into three groups according to the R/L ratio, 47% of the delusional (9/19) and 14% of the non-delusional patients (3/21; chi(2)=5.6, df=1, p=0.02) showed right markedly greater than left WTH.
Predominantly right involvement of the medial temporal lobe might be a determinant of paranoid delusions in the mild stages of Alzheimer's disease.

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Available from: Orazio Zanetti, Jul 03, 2014
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    • "One might speculate that vascular conditions lead to dysfunction in brain regions involved in psychotic symptoms. Hypertension is a known risk factor for stroke, which may result in lesions or affect the neural circuitry in the temporal lobe, thought to be involved in the production of delusions (Lopez et al., 2001; Geroldi et al., 2000). Alternatively, psychotic symptoms may occur as a side effect of antihypertensive medications (e.g., Ahmad, 1996). "
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    ABSTRACT: To examine, in an exploratory analysis, the association between vascular conditions and the occurrence of neuropsychiatric symptoms (NPS) in a population-based sample of incident Alzheimer's disease (AD). The sample consisted of 254 participants, identified through two waves of assessment. NPS were assessed using the Neuropsychiatric Inventory. Prior to the onset of AD, data regarding a history of stroke, hypertension, hyperlipidemia, heart attack or coronary artery bypass graft (CABG), and diabetes were recorded. Logistic regression procedures were used to examine the relationship of each vascular condition to individual neuropsychiatric symptoms. Covariates considered were age, gender, education, APOE genotype, dementia severity, and overall health status. One or more NPS were observed in 51% of participants. Depression was most common (25.8%), followed by apathy (18.6%), and irritability (17.7%). Least common were elation (0.8%), hallucinations (5.6%), and disinhibition (6.0%). Stroke prior to the onset of AD was associated with increased risk of delusions (OR = 4.76, p = 0.02), depression (OR = 3.87, p = 0.03), and apathy (OR = 4.48, p = 0.02). Hypertension was associated with increased risk of delusions (OR = 2.34, p = 0.02), anxiety (OR = 4.10, p = 0.002), and agitation/aggression (OR = 2.82, p = 0.01). No associations were observed between NPS and diabetes, hyperlipidemia, heart attack or CABG, or overall health. Results suggest that a history of stroke and hypertension increase the risk of specific NPS in patients with AD. These conditions may disrupt neural circuitry in brain areas involved in NPS. Findings may provide an avenue for reduction in occurrence of NPS through the treatment or prevention of vascular risk conditions.
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    • "Lopez et al (2001) found resting left medial temporal and left dorsolateral prefrontal cortex abnormalities. Of four AD patients studied using positron emission tomography imaging, two with persecutory delusions and two with hallucinations, all had frontotemporal hypoperfusion relative to nonpsychotic AD patients (Geroldi et al 2000a). Patients with hallucinations had, in addition, right parietal hypoperfusion and those two with aggression showed right orbital, right cingulate, and right dorsolateral activation (Lopez et al 2001). "
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    ABSTRACT: Assessments and clinical understanding of late-onset delusions in the elderly are inconsistent and often incomplete. In this review, we consider the prevalence, neurobehavioral features, and neuroanatomic correlations of delusions in elderly persons - those with documented cognitive decline and those with no evidence of cognitive decline. Both groups exhibit a common phenotype: delusions are either of persecution or of misidentification. Late-onset delusions show a nearly complete absence of the grandiose, mystical, or erotomanic content typical of early onset psychoses. Absent also from both elderly populations are formal thought disorders, thought insertions, and delusions of external control. Neuroimaging and behavioral studies suggest a frontotemporal localization of delusions in the elderly, with right hemispheric lateralization in delusional misidentification and left lateralization in delusions of persecution. We propose that delusions in the elderly reflect a common neuroanatomic and functional phenotype, and we discuss applications of our proposal to diagnosis and treatment.
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