My doctor told me I had a bunch of white matter hyperintensities but never showed me them on any scan, so I don't know the size, location or any intervention needed, because my doctor knew nothing and did nothing. I have zero cognitive impairment.
I think my semantic fluency is still good but since I'm only 65 I may not be considered older yet and since stroke not healthy, am right handed though.
Effects of White Matter Hyperintensities on Verbal Fluency in Healthy Older Adults and MCI/AD/a>
Alar Kaskikallio1*, 
Mira Karrasch1, Juha Koikkalainen2, 
Jyrki Lötjönen2, 
Juha O. Rinne3,4, Terhi Tuokkola3, Riitta Parkkola5 and Petra Grönholm-Nyman1
- 1Department of Psychology, Åbo Akademi University, Turku, Finland
- 2Combinostics Ltd., Tampere, Finland
- 3Turku PET-Centre, University of Turku, Turku, Finland
- 4Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland
- 5Department of Radiology, University Hospital of Turku, Turku, Finland
Background: White matter hyperintensities (WMHs)
are markers for cerebrovascular pathology, which are frequently seen in
patients with mild cognitive impairment (MCI) and Alzheimer’s disease
(AD). Verbal fluency is often impaired especially in AD, but little
research has been conducted concerning the specific effects of WMH on
verbal fluency in MCI and AD.
Objective: Our aim was to examine the
relationship between WMH and verbal fluency in healthy old age and
pathological aging (MCI/AD) using quantified MRI data.
Methods: Measures for semantic and phonemic
fluency as well as quantified MRI imaging data from a sample of 42
cognitively healthy older adults and 44 patients with MCI/AD (total n
= 86) were utilized. Analyses were performed both using the total
sample that contained seven left-handed/ambidextrous participants, as
well with a sample containing only right-handed participants (n = 79) in order to guard against possible confounding effects regarding language lateralization.
Results: After controlling for age and education
and adjusting for multiple correction, WMH in the bilateral frontal and
parieto-occipital areas as well as the right temporal area were
associated with semantic fluency in cognitively healthy and MCI/AD
patients but only in the models containing solely right-handed
participants.
Conclusion: The results indicate that white matter
pathology in both frontal and parieto-occipital cerebral areas may have
associations with impaired semantic fluency in right-handed older
adults. However, elevated levels of WMH do not seem to be associated
with cumulative effects on verbal fluency impairment in patients with
MCI or AD. Further studies on the subject are needed.
Introduction
Aging is often accompanied by vascular changes in cerebral white matter (WM) (Feigin et al., 2003), which typically show up as white matter hyperintensities (WMHs) when magnetic resonance imaging (MRI) is utilized (Pantoni et al., 2007).
These cerebrovascular changes can have a variety of effects on
cognitive functions, including impairments to information processing
speed, executive functions, working memory, episodic memory, as well as
linguistic functions (de Groot et al., 2000; Gunning-Dixon and Raz, 2000; Nordahl et al., 2005, 2006; Au et al., 2006; Pantoni et al., 2007; Zhou and Jia, 2009; Chin et al., 2012; Jokinen et al., 2012; Maillard et al., 2012; Lampe et al., 2019).
Cerebrovascular pathology and Alzheimer’s disease (AD) are intertwined in several respects, as both share common risk factors (Duron and Hanon, 2008) and often overlap and co-occur (Toledo et al., 2013). Furthermore, the risk for developing AD is increased by vascular diseases and elevated WMH (Breteler, 2000; Wolf et al., 2000; Prins et al., 2004), whereas AD patients exhibit elevated levels of cerebral WM pathology (Brickman, 2013) as well as degeneration in specific WM tracts (Mito et al., 2018).
Thus, it is of critical importance to study the effects of WM pathology
on cognition in AD as well as in mild cognitive impairment (MCI), which
is often an early stage of AD. However, the topic has received
considerably less attention than the association between gray matter
morphology and cognition (for exceptions, see Brickman et al., 2008; Brickman, 2013; Ramirez et al., 2014; Bilello et al., 2015; Mito et al., 2018; Kaskikallio et al.,2019a,b).
A deficit that occurs fairly early in AD is impaired word finding (Farrell et al., 2014).
Word generation is commonly measured by verbal fluency (VF) tasks that
involve generating words according to cues within a preset time
interval: category cues are used for semantic fluency and letter cues
for phonological fluency (Lezak et al., 2012).
Verbal fluency tasks require using a variety of executive control
processes (e.g., focusing on the task, updating material, inhibiting
irrelevant responses) and are thus also seen as effective probes for
executive functioning (Henry and Crawford, 2004). Overall, AD patients appear to exhibit larger impairments in semantic fluency than in phonological fluency (Henry et al., 2004).
This likely reflects the deterioration of the semantic memory store
traditionally linked to accumulating neuropathological changes in AD (Chertkow and Bub, 1990; Hodges et al., 1992).
Functional neuroimaging studies have indicated that VF tasks rely on relatively left-lateralized cortical networks (Birn et al., 2010),
involving the frontal and temporal regions, anterior cingulate,
superior parietal cortex, left hippocampus, thalamus, and cerebellum (Phelps et al., 1997; Gourovitch et al., 2000; Abrahams et al., 2003; Costafreda et al., 2006; Robinson et al., 2012; Biesbroek et al., 2016).
Furthermore, the right hemisphere has been suggested to be more
involved in semantic fluency tasks over phonological fluency tasks in a
number of studies (Schlösser et al., 1998; Donnelly et al., 2011; Glikmann-Johnston et al., 2015). More specifically, areas in the left inferior/middle frontal cortex seem to contribute to both types of fluency (Costafreda et al., 2006; Wagner et al., 2014; Schmidt et al., 2019).
However, phonological fluency seems to rely relatively more on the left
frontal cortex (presumably reflecting the need for additional strategic
effort) and semantic fluency relatively more on the left temporal
cortex (presumably reflecting the need for retrieval from semantic
memory) (Henry and Crawford, 2004; Baldo et al., 2006, 2010).
Since phonological tasks require more effort and executive control,
they are expected to impose more substantial demands on planning and
strategy formation than semantic fluency tasks, which can rely more on
utilizing pre-existing semantic networks (Henry and Crawford, 2004). Nonetheless, various retrieval strategies can be used in both types of tasks.
According to the dual stream model, the system for
processing auditory speech involves two language streams that diverge
from the superior temporal gyrus (Hickok and Poeppel, 2007; Saur et al., 2008).
A left-dominant dorsal stream connects the superior temporal lobe and
posterior frontal premotor association cortices via the arcuate
fasciculus and superior longitudinal fasciculus, facilitating
sensorimotor language production. On the other hand, a bilateral ventral
language stream connects the superior and middle temporal lobe with the
ventrolateral prefrontal cortex via the extreme capsule and the
middle/inferior longitudinal fasciculi, extracting meaning from sounds (Hickok and Poeppel, 2007; Saur et al., 2008).
The microstructural integrity of WM tracts from both pathways has been
associated with VF performance in studies that have included healthy
adolescents and adults as well as various clinical populations. These
tracts include the left arcuate fasciculus and the bilateral superior
longitudinal fasciculus for the dorsal stream (Peters et al., 2012; Allendorfer et al., 2016; Rodríguez-Aranda et al., 2016; Blecher et al., 2019), and the bilateral inferior longitudinal fasciculus for the ventral stream (Allendorfer et al., 2016; Rodríguez-Aranda et al., 2016; Blecher et al., 2019). Associations have also been reported for the bilateral frontal aslant track (Catani et al., 2013; Kinoshita et al., 2015; Blecher et al., 2019) and the corpus callosum (Rodríguez-Aranda et al., 2016).
Although numerous studies have been published on the
neuroanatomic correlates of VF, research about the neurocorrelations
between WM and VF in MCI and AD populations has been fairly limited.
Studies utilizing diffusion tensor imaging have reported associations
between semantic fluency and WM microstructure measures in the corpus
callosum, right anterior periventricular, and posterior periventricular
regions (Kavcic et al., 2008; Chen et al., 2009). Likewise, Rodríguez-Aranda et al. (2016)
reported associations between semantic fluency and a bilateral network
of WM tracts (uncinate fasciculus, inferior fronto-occipital fasciculus,
forceps minor, and corpus callosum) as well as phonological fluency and
several left-hemisphere tracts (anterior thalamic radiation, superior
longitudinal fasciculus, inferior longitudinal fasciculus). Finally, Serra et al. (2010) reported that no significant associations exist for these groups specifically.
Overall, the research literature regarding the effects of
WM pathology on verbal fluency in AD is quite limited, and previous
studies have contained fairly small samples. We have previously examined
effects of WM pathology on both general cognitive functioning (Kaskikallio et al., 2019a) as well as on specific cognitive domains (Kaskikallio et al., 2019b, 2020)
in cognitively healthy adults and patients with MCI or AD. In these
studies, verbal fluency was not included in the verbal function domain
score (Kaskikallio et al., 2019b, 2020)
due to relatively low shared variance with the other verbal tasks in
factor analysis—thus supporting the view that VF tasks tap additional
cognitive processes such as executive functions (e.g., Henry and Crawford, 2004; Aita et al., 2016). In this study, we investigated verbal fluency per se.
The aim was to examine the associations between WM pathology and VF in a
sample consisting of a group of cognitively healthy older adults and a
group of amnestic MCI and AD patients. A special focus was on examining
possible group-wise effects, i.e., would there be differences in the
effects of WM pathology between cognitively healthy and MCI/AD patients.
The sample utilized here is a portion of the sample that has been used
previously (Kaskikallio et al., 2019a, 2020), with the quantified MRI being utilized in Kaskikallio et al. (2019b).
Alar Kaskikallio1*, Mira Karrasch1, Juha Koikkalainen2, Jyrki Lötjönen2, Juha O. Rinne3,4, Terhi Tuokkola3, Riitta Parkkola5 and Petra Grönholm-Nyman1- 1Department of Psychology, Åbo Akademi University, Turku, Finland
- 2Combinostics Ltd., Tampere, Finland
- 3Turku PET-Centre, University of Turku, Turku, Finland
- 4Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland
- 5Department of Radiology, University Hospital of Turku, Turku, Finland
Background: White matter hyperintensities (WMHs) are markers for cerebrovascular pathology, which are frequently seen in patients with mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Verbal fluency is often impaired especially in AD, but little research has been conducted concerning the specific effects of WMH on verbal fluency in MCI and AD.
Objective: Our aim was to examine the relationship between WMH and verbal fluency in healthy old age and pathological aging (MCI/AD) using quantified MRI data.
Methods: Measures for semantic and phonemic fluency as well as quantified MRI imaging data from a sample of 42 cognitively healthy older adults and 44 patients with MCI/AD (total n = 86) were utilized. Analyses were performed both using the total sample that contained seven left-handed/ambidextrous participants, as well with a sample containing only right-handed participants (n = 79) in order to guard against possible confounding effects regarding language lateralization.
Results: After controlling for age and education and adjusting for multiple correction, WMH in the bilateral frontal and parieto-occipital areas as well as the right temporal area were associated with semantic fluency in cognitively healthy and MCI/AD patients but only in the models containing solely right-handed participants.
Conclusion: The results indicate that white matter pathology in both frontal and parieto-occipital cerebral areas may have associations with impaired semantic fluency in right-handed older adults. However, elevated levels of WMH do not seem to be associated with cumulative effects on verbal fluency impairment in patients with MCI or AD. Further studies on the subject are needed.
Introduction
Aging is often accompanied by vascular changes in cerebral white matter (WM) (Feigin et al., 2003), which typically show up as white matter hyperintensities (WMHs) when magnetic resonance imaging (MRI) is utilized (Pantoni et al., 2007). These cerebrovascular changes can have a variety of effects on cognitive functions, including impairments to information processing speed, executive functions, working memory, episodic memory, as well as linguistic functions (de Groot et al., 2000; Gunning-Dixon and Raz, 2000; Nordahl et al., 2005, 2006; Au et al., 2006; Pantoni et al., 2007; Zhou and Jia, 2009; Chin et al., 2012; Jokinen et al., 2012; Maillard et al., 2012; Lampe et al., 2019).
Cerebrovascular pathology and Alzheimer’s disease (AD) are intertwined in several respects, as both share common risk factors (Duron and Hanon, 2008) and often overlap and co-occur (Toledo et al., 2013). Furthermore, the risk for developing AD is increased by vascular diseases and elevated WMH (Breteler, 2000; Wolf et al., 2000; Prins et al., 2004), whereas AD patients exhibit elevated levels of cerebral WM pathology (Brickman, 2013) as well as degeneration in specific WM tracts (Mito et al., 2018). Thus, it is of critical importance to study the effects of WM pathology on cognition in AD as well as in mild cognitive impairment (MCI), which is often an early stage of AD. However, the topic has received considerably less attention than the association between gray matter morphology and cognition (for exceptions, see Brickman et al., 2008; Brickman, 2013; Ramirez et al., 2014; Bilello et al., 2015; Mito et al., 2018; Kaskikallio et al.,2019a,b).
A deficit that occurs fairly early in AD is impaired word finding (Farrell et al., 2014). Word generation is commonly measured by verbal fluency (VF) tasks that involve generating words according to cues within a preset time interval: category cues are used for semantic fluency and letter cues for phonological fluency (Lezak et al., 2012). Verbal fluency tasks require using a variety of executive control processes (e.g., focusing on the task, updating material, inhibiting irrelevant responses) and are thus also seen as effective probes for executive functioning (Henry and Crawford, 2004). Overall, AD patients appear to exhibit larger impairments in semantic fluency than in phonological fluency (Henry et al., 2004). This likely reflects the deterioration of the semantic memory store traditionally linked to accumulating neuropathological changes in AD (Chertkow and Bub, 1990; Hodges et al., 1992).
Functional neuroimaging studies have indicated that VF tasks rely on relatively left-lateralized cortical networks (Birn et al., 2010), involving the frontal and temporal regions, anterior cingulate, superior parietal cortex, left hippocampus, thalamus, and cerebellum (Phelps et al., 1997; Gourovitch et al., 2000; Abrahams et al., 2003; Costafreda et al., 2006; Robinson et al., 2012; Biesbroek et al., 2016). Furthermore, the right hemisphere has been suggested to be more involved in semantic fluency tasks over phonological fluency tasks in a number of studies (Schlösser et al., 1998; Donnelly et al., 2011; Glikmann-Johnston et al., 2015). More specifically, areas in the left inferior/middle frontal cortex seem to contribute to both types of fluency (Costafreda et al., 2006; Wagner et al., 2014; Schmidt et al., 2019). However, phonological fluency seems to rely relatively more on the left frontal cortex (presumably reflecting the need for additional strategic effort) and semantic fluency relatively more on the left temporal cortex (presumably reflecting the need for retrieval from semantic memory) (Henry and Crawford, 2004; Baldo et al., 2006, 2010). Since phonological tasks require more effort and executive control, they are expected to impose more substantial demands on planning and strategy formation than semantic fluency tasks, which can rely more on utilizing pre-existing semantic networks (Henry and Crawford, 2004). Nonetheless, various retrieval strategies can be used in both types of tasks.
According to the dual stream model, the system for processing auditory speech involves two language streams that diverge from the superior temporal gyrus (Hickok and Poeppel, 2007; Saur et al., 2008). A left-dominant dorsal stream connects the superior temporal lobe and posterior frontal premotor association cortices via the arcuate fasciculus and superior longitudinal fasciculus, facilitating sensorimotor language production. On the other hand, a bilateral ventral language stream connects the superior and middle temporal lobe with the ventrolateral prefrontal cortex via the extreme capsule and the middle/inferior longitudinal fasciculi, extracting meaning from sounds (Hickok and Poeppel, 2007; Saur et al., 2008). The microstructural integrity of WM tracts from both pathways has been associated with VF performance in studies that have included healthy adolescents and adults as well as various clinical populations. These tracts include the left arcuate fasciculus and the bilateral superior longitudinal fasciculus for the dorsal stream (Peters et al., 2012; Allendorfer et al., 2016; Rodríguez-Aranda et al., 2016; Blecher et al., 2019), and the bilateral inferior longitudinal fasciculus for the ventral stream (Allendorfer et al., 2016; Rodríguez-Aranda et al., 2016; Blecher et al., 2019). Associations have also been reported for the bilateral frontal aslant track (Catani et al., 2013; Kinoshita et al., 2015; Blecher et al., 2019) and the corpus callosum (Rodríguez-Aranda et al., 2016).
Although numerous studies have been published on the neuroanatomic correlates of VF, research about the neurocorrelations between WM and VF in MCI and AD populations has been fairly limited. Studies utilizing diffusion tensor imaging have reported associations between semantic fluency and WM microstructure measures in the corpus callosum, right anterior periventricular, and posterior periventricular regions (Kavcic et al., 2008; Chen et al., 2009). Likewise, Rodríguez-Aranda et al. (2016) reported associations between semantic fluency and a bilateral network of WM tracts (uncinate fasciculus, inferior fronto-occipital fasciculus, forceps minor, and corpus callosum) as well as phonological fluency and several left-hemisphere tracts (anterior thalamic radiation, superior longitudinal fasciculus, inferior longitudinal fasciculus). Finally, Serra et al. (2010) reported that no significant associations exist for these groups specifically.
Overall, the research literature regarding the effects of WM pathology on verbal fluency in AD is quite limited, and previous studies have contained fairly small samples. We have previously examined effects of WM pathology on both general cognitive functioning (Kaskikallio et al., 2019a) as well as on specific cognitive domains (Kaskikallio et al., 2019b, 2020) in cognitively healthy adults and patients with MCI or AD. In these studies, verbal fluency was not included in the verbal function domain score (Kaskikallio et al., 2019b, 2020) due to relatively low shared variance with the other verbal tasks in factor analysis—thus supporting the view that VF tasks tap additional cognitive processes such as executive functions (e.g., Henry and Crawford, 2004; Aita et al., 2016). In this study, we investigated verbal fluency per se. The aim was to examine the associations between WM pathology and VF in a sample consisting of a group of cognitively healthy older adults and a group of amnestic MCI and AD patients. A special focus was on examining possible group-wise effects, i.e., would there be differences in the effects of WM pathology between cognitively healthy and MCI/AD patients. The sample utilized here is a portion of the sample that has been used previously (Kaskikallio et al., 2019a, 2020), with the quantified MRI being utilized in Kaskikallio et al. (2019b).
No comments:
Post a Comment