Auditory hallucinations, top-down processing and language perception: a general population study.

BACKGROUND: Studies investigating the underlying mechanisms of hallucinations in patients with schizophrenia suggest that an imbalance in top-down expectations v. bottom-up processing underlies these errors in perception. This study evaluates this hypothesis by testing if individuals drawn from the general population who have had auditory hallucinations (AH) have more misperceptions in auditory language perception than those who have never hallucinated. METHODS: We used an online survey to determine the presence of hallucinations. Participants filled out the Questionnaire for Psychotic Experiences and participated in an auditory verbal recognition task to assess both correct perceptions (hits) and misperceptions (false alarms). A hearing test was performed to screen for hearing problems. RESULTS: A total of 5115 individuals from the general Dutch population participated in this study. Participants who reported AH in the week preceding the test had a higher false alarm rate in their auditory perception compared with those without such (recent) experiences. The more recent the AH were experienced, the more mistakes participants made. While the presence of verbal AH (AVH) was predictive for false alarm rate in auditory language perception, the presence of non-verbal or visual hallucinations were not. CONCLUSIONS: The presence of AVH predicted false alarm rate in auditory language perception, whereas the presence of non-verbal auditory or visual hallucinations was not, suggesting that enhanced top-down processing does not transfer across modalities. More false alarms were observed in participants who reported more recent AVHs. This is in line with models of enhanced influence of top-down expectations in persons who hallucinate.

A linguistic comparison between auditory verbal hallucinations in patients with a psychotic disorder and in nonpsychotic individuals: Not just what the voices say, but how they say it.

BACKGROUND: Auditory verbal hallucinations (AVH) in psychotic patients are associated with activation of right hemisphere language areas, although this hemisphere is non-dominant in most people. Language generated in the right hemisphere can be observed in aphasia patients with left hemisphere damage. It is called "automatic speech", characterized by low syntactic complexity and negative emotional valence. AVH in nonpsychotic individuals, by contrast, predominantly have a neutral or positive emotional content and may be less dependent on right hemisphere activity. We hypothesize that right hemisphere language characteristics can be observed in the language of AVH, differentiating psychotic from nonpsychotic individuals. METHOD: 17 patients with a psychotic disorder and 19 nonpsychotic individuals were instructed to repeat their AVH verbatim directly upon hearing them. Responses were recorded, transcribed and analyzed for total words, mean length of utterance, proportion of grammatical utterances, proportion of negations, literal and thematic perseverations, abuses, type-token ratio, embeddings, verb complexity, noun-verb ratio, and open-closed class ratio. RESULTS: Linguistic features of AVH overall differed between groups F(13,24)=3.920, p=0.002; Pillai's Trace 0.680. AVH of psychotic patients compared with AVH of nonpsychotic individuals had a shorter mean length of utterance, lower verb complexity, and more verbal abuses and perseverations (all p<0.05). Other features were similar between groups. CONCLUSION: AVH of psychotic patients showed lower syntactic complexity and higher levels of repetition and abuses than AVH of nonpsychotic individuals. These differences are in line with a stronger involvement of the right hemisphere in the origination of AVH in patients than in nonpsychotic voice hearers.

Markers of low-grade inflammation and endothelial dysfunction are related to reduced information processing speed and executive functioning in an older population - the Hoorn Study.

Low-grade inflammation and endothelial dysfunction are related to cognitive decline and dementia, in a complex interplay with vascular factors and aging. We investigated, in an older population, low-grade inflammation and endothelial dysfunction in relation to detailed assessment of cognitive functioning. Furthermore, we explored this association within the context of vascular factors. 377 participants (73 ± 6 years) of the population-based Hoorn Study were included. In plasma samples of 2000-2001 (n=363) and/or 2005-2008 (n=323), biomarkers were determined of low-grade inflammation (CRP, TNF-alpha, IL-6, IL-8, SAA, MPO, and sICAM-1) and endothelial dysfunction (vWF, sICAM-1, sVCAM-1, sTM, sE-selectin). In 2005-2008, all participants underwent neuropsychological examination. Composite z-scores were computed for low-grade inflammation and endothelial dysfunction at both time points, and for six domains of cognitive functioning (abstract reasoning, memory, information processing speed, attention and executive functioning, visuoconstruction, and language). The association between low-grade inflammation and endothelial dysfunction, and cognitive functioning was evaluated with linear regression analysis. In secondary analyses, we explored the relation with vascular risk factors and cardiovascular disease. Low-grade inflammation and endothelial dysfunction were associated with worse performance on information processing speed and attention and executive functioning, in prospective and cross-sectional analyses (standardized betas ranging from -0.20 to -0.10). No significant relation with other cognitive domains was observed. Adjusting for vascular factors slightly attenuated the associations. Low-grade inflammation and endothelial dysfunction accounted for only 2.6% explained variance in cognitive functioning, on top of related vascular risk factors and cardiovascular disease. Bootstrapping analyses show that low-grade inflammation and endothelial dysfunction mediate the relation between vascular risk factors and cognitive functioning. This study shows that low-grade inflammation and endothelial dysfunction contribute to reduced information processing speed and executive functioning in an older population.

Albuminuria and cognitive functioning in an older population: the Hoorn study.

BACKGROUND/AIMS: Markers of vascular disease elsewhere in the body may reflect vascular abnormalities in the brain relevant to age-related cognitive decline and dementia. We examined the association between albuminuria, as a marker of microvascular damage, and cognition in older individuals. METHODS: 380 individuals (age 73 ± 6 years), participating in the population-based Hoorn Study, underwent extensive neuropsychological examination in 2005-2008, and urinary albumin-to-creatinine ratios measurements in 2000-2001 (n = 378) and/or 2005-2008 (n = 346). Cognition was expressed in z-scores on 6 domains. RESULTS: In 2000-2001, 42 participants were with and 336 without albuminuria, and in 2005-2008 51 were with and 295 were without. In age-, sex- and premorbid IQ-adjusted analyses, participants with albuminuria 5-7 years earlier had slightly lower z-scores for the domains attention and executive functioning [mean difference: -0.21 (95% CI -0.40 to -0.02)] and language [-0.36 (95% CI -0.63 to -0.09)]. No statistically significant differences in cognition were found between participants with and without albuminuria at the time of neuropsychological testing. CONCLUSION: Albuminuria predicts future modest cognitive decrements, but concurrent albuminuria is unrelated to cognitive functioning. The link between albuminuria and cognitive dysfunction may convey an etiological message, but because effect sizes were modest its value in prognostic models for cognitive decline may be limited.