A longitudinal study of reading ability in patients suffering from dementia

Irregular word reading as a marker of semantic decline in Alzheimer's disease: implications for premorbid intellectual ability measurement

BACKGROUND

Irregular word reading has been used to estimate premorbid intelligence in Alzheimer's disease (AD) dementia. However, reading models highlight the core influence of semantic abilities on irregular word reading, which shows early decline in AD. The primary objective of this study is to ascertain whether irregular word reading serves as an indicator of cognitive and semantic decline in AD, potentially discouraging its use as a marker for premorbid intellectual abilities.

METHOD

Six hundred eighty-one healthy controls (HC), 104 subjective cognitive decline, 290 early and 589 late mild cognitive impairment (EMCI, LMCI) and 348 AD participants from the Alzheimer's Disease Neuroimaging Initiative were included. Irregular word reading was assessed with the American National Adult Reading Test (AmNART). Multiple linear regressions were conducted predicting AmNART score using diagnostic category, general cognitive impairment and semantic tests. A generalized logistic mixed-effects model predicted correct reading using extracted psycholinguistic characteristics of each AmNART words. Deformation-based morphometry was used to assess the relationship between AmNART scores and voxel-wise brain volumes, as well as with the volume of a region of interest placed in the left anterior temporal lobe (ATL), a region implicated in semantic memory.

RESULTS

EMCI, LMCI and AD patients made significantly more errors in reading irregular words compared to HC, and AD patients made more errors than all other groups. Across the AD continuum, as well as within each diagnostic group, irregular word reading was significantly correlated to measures of general cognitive impairment / dementia severity. Neuropsychological tests of lexicosemantics were moderately correlated to irregular word reading whilst executive functioning and episodic memory were respectively weakly and not correlated. Age of acquisition, a primarily semantic variable, had a strong effect on irregular word reading accuracy whilst none of the phonological variables significantly contributed. Neuroimaging analyses pointed to bilateral hippocampal and left ATL volume loss as the main contributors to decreased irregular word reading performances.

CONCLUSIONS

While the AmNART may be appropriate to measure premorbid intellectual abilities in cognitively unimpaired individuals, our results suggest that it captures current semantic decline in MCI and AD patients and may therefore underestimate premorbid intelligence. On the other hand, irregular word reading tests might be clinically useful to detect semantic impairments in individuals on the AD continuum.

Irregular word reading as a marker of cognitive and semantic decline in Alzheimer's disease rather than an estimate of premorbid intellectual abilities

Background

Irregular word reading has been used to estimate premorbid intelligence in Alzheimer's disease (AD) dementia. However, reading models highlight the core influence of semantic abilities on irregular word reading, which shows early decline in AD. The general aim of this study is to determine whether irregular word reading is a valid estimate of premorbid intelligence, or a marker of cognitive and semantic decline in AD.

Method

681 healthy controls (HC), 104 subjective cognitive decline, 290 early and 589 late mild cognitive impairment (EMCI, LMCI) and 348 AD participants from the Alzheimer's Disease Neuroimaging Initiative were included. Irregular word reading was assessed with the American National Adult Reading Test (AmNART). Multiple linear regressions were conducted predicting AmNART score using diagnostic category, general cognitive impairment and semantic tests. A generalized logistic mixed-effects model predicted correct reading using extracted psycholinguistic characteristics of each AmNART words. Deformation-based morphometry was used to assess the relationship between AmNART scores and voxel-wise brain volumes, as well as with the volume of a region of interest placed in the left anterior temporal lobe (ATL).

Results

EMCI, LMCI and AD patients made significantly more errors in reading irregular words compared to HC, and AD patients made more errors than all other groups. Across the AD continuum, as well as within each diagnostic group, irregular word reading was significantly correlated to measures of general cognitive impairment / dementia severity. Neuropsychological tests of lexicosemantics were moderately correlated to irregular word reading whilst executive functioning and episodic memory were respectively weakly and not correlated. Age of acquisition, a primarily semantic variable, had a strong effect on irregular word reading accuracy whilst none of the phonological variables significantly contributed. Neuroimaging analyses pointed to bilateral hippocampal and left ATL volume loss as the main contributors to decreased irregular word reading performances.

Conclusions

Irregular word reading performances decline throughout the AD continuum, and therefore, premorbid intelligence estimates based on the AmNART should not be considered accurate in MCI or AD. Results are consistent with the theory of irregular word reading impairments as an indicator of disease severity and semantic decline.

Vision in Alzheimer's disease: a focus on the anterior afferent pathway

Visual dysfunction has long been recognized as a manifestation of Alzheimer's disease (AD), particularly in the form of visuospatial impairment during all stages of disease. However, investigations have revealed findings within the anterior (i.e., pregeniculate) afferent visual pathways that rely on retinal imaging and electrophysiologic methodologies for detection. Here we focus on the anterior afferent visual pathways in AD and the measures used for assessment, including optical coherence tomography, electrophysiology, color vision testing and threshold visual field perimetry. A brief summary of higher order visual dysfunction is also included to allow the reader to keep in context the broader findings of afferent visual dysfunction in AD.

Vocabulary is an appropriate measure of premorbid intelligence in a sample with heterogeneous educational level in Brazil

Crystallized intelligence refers to one's knowledge base and can be measured by vocabulary tests. Fluid intelligence is related to nonverbal aspects of intelligence, depends very little on previously acquired knowledge, and can be measured by tests such as Block Design (BD) and Raven Colored Matrices (RCM). Premorbid intelligence quotient (IQ) refers to one's intellectual ability level previous to the onset of disorders like mild cognitive impairment (MCI) and Alzheimer's disease (AD) and it is important to estimate disease severity. The objective was to compare performance in tests that measure crystallized and fluid intelligence in healthy subjects and patients with amnestic MCI (aMCI) and AD. One hundred forty-four participants (aMCI (n = 38), AD (n = 45), and healthy controls (n = 61)) were submitted to neuropsychological tests (WAIS-III vocabulary, BD, and RCM). There were significant among groups, except for vocabulary, indicating a relative stability of crystallized intelligence in the continuum from normal to pathological cognitive decline. Vocabulary seems to be stable during the progression of the disease and useful as a measure of premorbid intelligence, that is, to estimate previous function in relation to the level of education and, as a collateral measure of cognition in people with low education.

The S-TOFHLA as a measure of functional literacy in patients with mild Alzheimer's disease or mild cognitive impairment

In developing countries, education levels vary dramatically, and the number of years of schooling does not always correlate with the true level of educational competency. This study was designed to verify the accuracy of the Short-Test of Functional Health Literacy in Adults (S-TOFHLA) in individuals with mild cognitive impairment (MCI) and mild Alzheimer's disease (AD), when compared with healthy controls (HCs), in order to assess its utility as a measure of functional literacy. One hundred forty-eight subjects were divided into three groups: HC (n = 61), MCI patients (n = 42), and AD patients (n = 45). The S-TOFHLA does not seem to be suitable as an instrument to measure functional literacy for patients with advanced cognitive impairment, but proved to be appropriate in both the HC group and MCI patients in numeracy and prove to be useful as an adjuvant to estimate IQ, reading ability, and premorbid IQ, as an indicator of cognitive reserve.

Quality, and not just quantity, of education accounts for differences in psychometric performance between african americans and white non-hispanics with Alzheimer's disease

The effect of race on cognitive test performance in the evaluation of Alzheimer's disease (AD) remains controversial. One factor that may contribute substantially to differences in cognitive test performance in diverse populations is education. The current study examined the extent to which quality of education, even after controlling for formal years of education, accounts for differences in cognitive performance between African Americans and White Non-Hispanics (WNHs). The retrospective cohort included 244 patients diagnosed with AD who self-identified as African Americans (n = 51) or WNHs (n = 193). The Wechsler Test of Adult Reading (WTAR) was used as an estimate of quality of education. In an analysis that controlled for traditional demographics, including age, sex, and years of formal education, African Americans scored significantly lower than WNHs on the Mini-Mental State Examination, as well as on neuropsychological tests of memory, attention, and language. However, after also adjusting for reading level, all previously observed differences were significantly attenuated. The attenuating effect remained even after controlling for disease severity, indicating that reading scores are not confounded by severity of dementia. These findings suggest that quality, and not just quantity, of education needs to be taken into account when assessing cognitive performance in African Americans with AD.

Estimating premorbid IQ in the prodromal phase of a neurodegenerative disease

Estimates of premorbid intellect are often used in neuropsychological assessment to make inferences about cognitive decline. To optimize the method of controlling for premorbid intellect in assessments of prodromal neurodegenerative disease, we examined performance on the American National Adult Reading Test (ANART; administered during Years 1 and 3) and the two-subtest version of the Wechsler Abbreviated Scale of Intelligence (WASI; administered in Years 2 and 4) in an ongoing prospective longitudinal study of 371 participants with prodromal Huntington disease and 51 participants with normal CAG repeats. Although both measures performed similarly, the ANART demonstrated slightly lower variability in performance over a 2-year period and had slightly higher test-retest reliability than the WASI.

Loss of basic lexical knowledge in old age

BACKGROUND

Basic lexical skills are hypothesised to be relatively preserved in mild dementia, but clinical studies have reported inconsistent results.

METHODS

More than 400 older Catholic nuns, priests and brothers recruited from groups across the USA completed annual evaluations for up to 15 years, died and underwent brain autopsy. Each clinical evaluation included administration of a 20-item word reading test and a 15-item vocabulary test, which were combined to form a composite measure of word knowledge. In a uniform neuropathological examination, Alzheimer's disease pathology was quantified with a composite index of plaques and tangles, and the presence of gross and microscopic cerebral infarctions and Lewy bodies was recorded.

RESULTS

The post-mortem level of Alzheimer's disease neuropathology was linearly related to rate of decline in word knowledge. Decline was nearly fourfold faster at a relatively high level of pathology (75th percentile) compared with a relatively low level (25th percentile). Neocortical (but not nigral or limbic) Lewy bodies and gross (but not microscopic) cerebral infarction were also associated with a more rapid decline in word knowledge. Effects for word reading and vocabulary were similar, except that gross cerebral infarction was associated with accelerated decline in vocabulary, but not in word reading.

CONCLUSION

Common neuropathological changes associated with late-life dementia impair word knowledge in old age, calling into question the use of word knowledge tests to estimate premorbid cognitive ability.

Estimation of premorbid IQ in individuals with Alzheimer's disease using Japanese ideographic script (Kanji) compound words: Japanese version of National Adult Reading Test

The National Adult Reading Test (NART) is widely used as a measure of premorbid IQ of the English-speaking patients with dementia. The purpose of the present study was to develop a Japanese version of the NART (JART), using 50 Japanese irregular words, all of which are Kanji (ideographic script) compound words. Reading performance based on JART and IQ as measured by the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was examined in a sample of 100 normal elderly (NE) persons and in 70 age-, sex-, and education-matched patients with Alzheimer's disease (AD). The NE group was randomly divided into the NE calculation group (n=50) and the NE validation group (n=50). Using the NE calculation group, a linear regression equation was obtained in which the observed full-scale IQ (FSIQ) was regressed on the reading errors of the JART. When the regressed equation computed from the NE calculation group was applied to the NE validation group, the predicted FSIQ adequately fit the observed FSIQ (R2=0.78). Further, independent t-tests showed that the JART-predicted IQs were not significantly different between the NE and AD groups, whereas the AD group performed worse in the observed IQs. The reading ability of Kanji compound words is well-preserved in Japanese patients with AD. The JART is a valid scale for evaluating premorbid IQ in patients with AD.

Stability of estimated IQ across mood state in patients with bipolar disorder

OBJECTIVES

The goal of this study was to assess the impact of mania symptoms on the stability of the American version of the National Adult Reading Test (ANART), a measure that provides a putative estimate of premorbid intellectual functioning.

METHODS

The ANART was administered to a sample of 10 inpatients with bipolar disorder who were experiencing an acute episode of mania. During a subsequent follow-up visit during which these individuals exhibited at most minimal mood symptoms, the ANART was re-administered.

RESULTS

ANART estimated intelligence quotient (IQ) scores during mania and affective stability were assessed in the 10 patients using a paired sample t-test. Within-subject performance across the two mood states did not significantly differ [t(9) = -1.24, p = 0.25]. Additionally, the greatest individual difference across mood states was only 3.68 points, and the average estimated IQ difference across mood states was 1.66.

CONCLUSIONS

While the results are preliminary and based on a small sample, the highly consistent scores achieved across mood states in this study suggest that the ANART is a reliable indicator of premorbid IQ.

Lexical processing in Spanish patients with probable Alzheimer’s disease

Twenty Spanish patients with probable Alzheimer's disease (AD) and 20 matched controls were given a battery of 17 tasks involving object recognition and the spoken and written perception and production of words and non-words. The AD patients were significantly impaired on nine of the tasks. Prominent among these were tasks that involve semantic processing, though non-word reading was also impaired. Performance on a category fluency task best discriminated AD patients from controls. It is proposed that impairment to semantic processing underlies most of the observed deficits on lexical processing tasks in patients with early AD, but that non-word reading may be sensitive to additional, mild impairments to phonological representations caused by extension of the degenerative process from anterior to posterior temporal regions.

Health literacy and performance on the Mini-Mental State Examination

The objectives of the study were to determine the relationship between functional health literacy and performance on the Mini-Mental State Examination (MMSE). New Medicare managed-care enrollees aged 65 years and older, living independently in the community in four US cities (Cleveland, Houston, Tampa, and Fort Lauderdale/Miami), were eligible to participate. In-home interviews were conducted to determine demographics and health status, and interviewers then administered the Short Test of Functional Health Literacy in Adults (S-TOFHLA) and the MMSE. We then determined the relationship between functional health literacy and the MMSE, including total scores, subscale scores (orientation to time, orientation to place, registration, attention and calculation, recall, language, and visual construction), and individual items. Functional health literacy was linearly related to the total MMSE score across the entire range of S-TOFHLA scores (R(2) = 0.39, p < 0.001). This relationship between health literacy and MMSE was consistent across all MMSE subscales and individual items. Adjustment for chronic conditions and self-reported overall health did not change the relationship between health literacy and MMSE score. Health literacy was related to MMSE performance even for subscales of the MMSE that were not postulated to be directly dependent on reading ability or education (e.g. delayed recall). These results suggest that the lower MMSE scores for patients with low health literacy are only partly due to 'test bias' and also result from true differences in cognitive functioning. 'Adjusting' MMSE scores for an individual's functional health literacy may be inappropriate because it may mask true differences in cognitive functioning.

The association between age and health literacy among elderly persons

OBJECTIVE

To examine why older age groups have worse functional health literacy.

METHODS

Home interviews were conducted with community-dwelling elderly persons (n = 2,774) to determine demographics, years of school completed, newspaper reading frequency, chronic diseases, and health status. Participants completed the Short Test of Functional Health Literacy in Adults (S-TOFHLA, range 0-100) and the Mini Mental State Examination (MMSE).

RESULTS

Mean S-TOFHLA scores declined 1.4 points (95% CI 1.3-1.5) for every year increase in age (p < .001). After adjusting for sex, race, ethnicity, and education, the S-TOFHLA score declined 1.3 points (95% CI 1.2-1.4) for every year increase in age. Even after adjustment for performance on the MMSE, the S-TOFHLA score declined 0.9 points (95% CI 0.8-1.0) for every year increase in age (p < .001). Differences in newspaper reading frequency, visual acuity, chronic medical conditions, and health status, did not explain the lower literacy of older participants.

DISCUSSION

Functional health literacy was markedly lower among older age groups even after adjusting for differences in MMSE performance, newspaper reading frequency, health status, and visual acuity. Future studies should prospectively examine whether functional literacy declines with age and whether this is explained by declines in cognitive function.

Cognitive function in primary progressive and transitional progressive multiple sclerosis: a controlled study with MRI correlates

The relative rarity of primary progressive (PP) and transitional progressive (TP) multiple sclerosis has meant that little documentation of cognitive function in such patients is currently available. The aim of this study was to investigate the cognitive skills of patients with PP and TP multiple sclerosis relative to matched healthy controls, and to examine the relationship of this impairment to MRI parameters. Sixty-three patients (43 PP, 20 TP) were individually matched with healthy controls, who undertook the same cognitive tasks as the patient group. The neuropsychological assessment comprised Rao's brief repeatable battery, a reasoning test, and a measure of depression. Patients also underwent T1- and T2-weighted brain MRI. These patients were taken from a larger cohort (158 PP, 33 TP) in whom it had been demonstrated that the re were no significant differences between the mean scores of the PP and TP groups on any of the cognitive variables. The 63 patients were therefore taken as one group for comparison with the healthy controls. These patients performed significantly worse than the controls in tests of verbal memory, attention, verbal fluency and spatial reasoning. An impairment index was constructed and applied to the patient data. This correlated modestly with T2-lesion load (r = 0.45, P = 0.01), T1-hypointensity load (r = 0.45, P = 0.01) and cerebral volume (r = -0.35, P = 0.01). Thus, PP and TP multiple sclerosis patients demonstrate significant cognitive dysfunction when compared with matched healthy controls. The relationship between this impairment and MRI parameters is moderate, suggesting that cognitive dysfunction in PP and TP multiple sclerosis has a complex and multifactorial aetiology, which is not adequately explained by pathology as demonstrated on conventional MRI.

Multiple sclerosis: a preliminary study of selected variables affecting rehabilitation outcome

PROBLEM

The diversity of physical and cognitive impairments seen in progressive multiple sclerosis (MS), make it difficult to identify the factors that influence neurorehabilitation outcome. Improvements in a motor disability scale must be considered in the context of the patient's physical and cognitive starting points, if the process of neurorehabilitation is to be properly understood.

METHOD

Data was collected from 38 patients (mean age 41 years, 16 men and 22 women) with clinically definite MS (of whom all but one were in the progressive phase of the disease), who were consecutively admitted to a neurorehabilitation unit. Patients' physical disability was assessed on the motor scale of the Functional Independence Measure (FIM) on admission and discharge. Cognitive and neurological assessments were completed on admission. The cognitive battery comprised the WAIS-R, NART, RMT, CVLT CMT, GNT, GDA, and VOSP (some in short form). Emotional measures were the STAI, STAXI and BDI.

RESULTS

The mean improvement on the FIM was 6 points. A multiple regression analysis was performed to determine which cognitive and neurological variables related to reduced disability after neurorehabilitation. To take account of each patient's starting point, the model included their FIM admission score. This variable, together with vocabulary skills and cerebellar function accounted for 57% of the variance in the patients' improvements. These results suggest that verbal intelligence and cerebellar function are influential in determining rehabilitation outcome. Although these findings will be unsurprising to clinicians, this is the first quantitative demonstration of these effects.

Word reading in Alzheimer's disease: cross-sectional and longitudinal analyses of response time and accuracy data

Using a list of high- and low-frequency regular and exception words, we measured the reading performance of three groups of subjects: patients with mild dementia of the Alzheimer's type (DAT) at presentation (Stage 1) and 2-3 years later (Stage 2); moderately severe DAT patients; and control subjects. In the longitudinally studied patients, there was a dramatic increase in response times (RTs) from Stage 1 to Stage 2, but little change in either error rate or pattern. By contrast, a comparison of the Stage 2 with the Moderate patients revealed similar RTs but a significant increase in error rate for the Moderate group, particularly on low-frequency exception words. These two results for word naming were almost exactly mirrored by effects in picture naming. We conclude that correct word reading, especially for less common words with atypical spelling-sound correspondences, is compromised in DAT only when the disease produces a significant deterioration of semantic memory. These results are relevant to current theories about normal and impaired reading processes.

Premorbid intelligence estimation and level of dementia in Alzheimer's disease

Simple sight-word reading tasks have demonstrated utility in the estimation of premorbid intelligence, although the effects of progressive dementia on such tasks has not been thoroughly examined. The present investigation sought to examine estimated IQ scores from the National Adult Reading Test-Revised (NART-R; Blair & Spreen, 1989) in relation to a WAIS-R-based (Wechsler, 1981) estimate of IQ in a series of patients with probable Alzheimer's disease across varying levels of dementia. Results suggest that while NART-R scores do show a decrement with dementia severity, this decline is mild, in contrast to traditionally based IQ scores and other measures of cognitive function, which show more marked declines. Similarly, compared with other tasks, the NART-R showed the strongest correlation with education across the sample as a whole, while the other indices were more related to level of dementia. These findings support the use of measures such as the NART-R in estimating premorbid intellectual functioning in patients at various levels of dementia severity, including those with more advanced cognitive deterioration.