Biomedical subjects

Louise H Phillips

Publications and source records attributed to Louise H Phillips.

18 recordsLinked to original sources

PubMed2006

The psychological, neurochemical and functional neuroanatomical mediators of the effects of positive and negative mood on executive functions.

In this review we evaluate the cognitive and neural effects of positive and negative mood on executive function. Mild manipulations of negative mood appear to have little effect on cognitive control processes, whereas positive mood impairs aspects of updating, planning and switching. These cognitive effects may be linked to neurochemistry: with positive mood effects mediated by dopamine while negative mood effects may be mediated by serotonin levels. Current evidence on the effects of mood on regional brain activity during executive functions, indicates that the prefrontal cortex is a recurrent site of integration between mood and cognition. We conclude that there is a disparity between the importance of this topic and awareness of how mood affects, executive functions in the brain. Most behavioural and neuroimaging studies of executive function in normal samples do not explore the potential role of variations in mood, yet the evidence we outline indicates that even mild fluctuations in mood can have a significant influence on neural activation and cognition.

Affect↗

PubMed2006

Global visual scanning abnormalities in schizophrenia and bipolar disorder.

Visual scanning of face images is widely reported to be abnormal in schizophrenia. This impaired processing has been proposed to be partly responsible for patients' disturbance in social interactions. The present study was designed to determine whether abnormal scanning is specific to images with social content or extends to other types of stimuli. Individuals with schizophrenia (n=22), bipolar disorder (n=19) and healthy controls (n=37) were asked to view a series of 28 images with or without socially important content (i.e. faces, landscapes, fractals and noise patterns) while their eye movements were recorded video-oculographically. Temporal and spatial characteristics of scan paths were compared for each patient group and picture type. Independent of image content, patients with schizophrenia exhibited fewer fixations, longer fixation duration, longer saccade duration and peak velocity, and smaller saccade amplitude compared with healthy controls. Patients with schizophrenia and bipolar disorder did not differ significantly from one another on any of the temporal variables recorded. Fixation location distributions of participants with schizophrenia differed significantly from that of healthy controls on all picture types and from patients with bipolar disorder on all but face images. Abnormal scanning in schizophrenia and also bipolar disorder was independent of stimulus type and therefore reflects a global visual scanning impairment not specific to faces. Spatial scanning characteristics but not temporal ones may serve as biomarkers in the functional psychoses.

Adult↗

PubMed2006

Theory of mind following traumatic brain injury: the role of emotion recognition and executive dysfunction.

A number of studies have now documented that traumatic brain injury (TBI) is associated with deficits in the recognition of basic emotions, the capacity to infer mental states of others (theory of mind), as well as executive functioning. However, no study to date has investigated the relationship between these three constructs in the context of TBI. In the current study TBI participants (N=16) were compared with demographically matched healthy controls (N=17). It was found that TBI participants' recognition of basic emotions, as well as their capacity for mental state attribution, was significantly reduced relative to controls. Performance on both of these measures was strongly correlated in the healthy control, but not in the TBI sample. In contrast, in the TBI (but not the control) sample, theory of mind was substantially correlated with performance on phonemic fluency, a measure of executive functioning considered to impose particular demands upon cognitive flexibility and self-regulation. These results are consistent with other evidence indicating that deficits in some aspects of executive functioning may at least partially underlie deficits in social cognition following TBI, and thus help explain the prevalence of social dysfunction in TBI.

Adult↗

PubMed2006

Age-related differences in the ability to perceive sad facial expressions.

BACKGROUND AND AIMS: Research has shown that the ability to label negative emotions displayed by facial expressions declines with age. Such studies, however, have tended to adopt the Ekman and Friesen (1976) Caucasian faces as their emotional stimuli. The purpose of the current study was to examine whether the age differences in identifying negative emotions are also found using the more recent Japanese and Caucasian Facial Expressions of Emotion (JACFEE). METHODS: In Experiment 1, 29 younger and 29 older individuals performed a verbal labeling emotion identification task (happy, sad, angry, frightened, disgusted, surprised, contemptuous). The ability to identify each emotion as a function of ethnicity across the age groups was examined. In order to reduce the verbal decision-making load on the task, a second experiment was conducted in which 60 younger and 60 older participants performed an emotion-matching task (sad, angry, contemptuous). RESULTS: In Experiment 1, older adults showed a significant decrement in the ability to recognize sad faces compared with younger adults, but no age x face ethnicity interaction was found. In Experiment 2, age differences were found when making same/different judgments regarding two sad faces or a sad and a contemptuous face. CONCLUSIONS: Results suggest that aging has an impact upon perceiving sad facial expressions, that this effect is not mediated by own-race versus other-race faces, and that age effects are not attributable to differences in verbal decision-making.

Adult↗

PubMed2006

A new conceptualization of alexithymia in the general adult population: implications for research involving older adults.

OBJECTIVE: The purpose of this study is to test the validity of existing conceptualizations of the alexithymia concept, with particular reference to aging. METHODS: Two hundred and forty-eight healthy adults completed measures of alexithymia and psychosocial functioning; younger and older adults (n=121) also completed a measure of emotional responsiveness. RESULTS: Older adults engaged in less introspective thought traditionally thought to denote increased alexithymia. However, reduced introspection was associated with improved mental wellbeing, and, thus, could not be construed as a deficit. Difficulty identifying and describing emotions did not differentiate older and younger adults, but were both associated with heightened depression, anxiety, and poor perceived quality of life. CONCLUSIONS: In clinical practice and research, the Toronto Alexithymia Scale (TAS) is almost exclusively used, with "total" score typically used to index alexithymia. As one of the subscales of the TAS measures reduced introspection, calculating total scores may not be appropriate and may particularly overestimate levels of alexithymia in older adulthood.

Adolescent↗

PubMed2006

Cognitive and psychosocial correlates of alexithymia following traumatic brain injury.

Changes in emotional and social behaviour are considered to be amongst the most common and debilitating consequences of traumatic brain injury (TBI). Little is known of the effects of TBI on alexithymia, which refers to impairment in aspects of understanding emotions. In the current study TBI patients (N=28) were compared with demographically matched healthy controls (N=31) on the Toronto Alexithymia Scale-20 (TAS-20), a measure that taps three distinct characteristics of the alexithymia concept; difficulty in identifying emotions, difficulty in describing emotions and externally oriented thinking. Patients and controls also completed measures of anxiety, depression, quality of life, and measures of fluency to assess executive function. Patients showed greater levels of alexithymia, in terms of difficulty identifying emotions and reduced introspection. Difficulty in identifying emotions was associated with poorer quality of life, even when depression and anxiety were controlled. Difficulty in identifying emotions was also uniquely associated with executive function deficits. Thus, although studies typically focus on aspects of cognitive change following head injury, these results lend support to Becerra et al.'s (Becerra, R., Amos, A., & Jongenelis, S. (2002). Organic alexithymia: a study of acquired emotional blindness. Brain Injury, 16, 633-645.) notion of an 'organic alexithymia', and suggest that more attention should be focused upon assessment of emotional change post-head injury.

Adolescent↗

PubMed2006

Age and planning tasks: the influence of ecological validity.

Planning ability is important in many everyday tasks, such as cooking and shopping. Previous studies have investigated aging effects on planning, looking at either widely used laboratory-based neuropsychological tasks such as the Tower of London (TOL) or more naturalistic planning tasks, such as organizing shopping errands. In the current study, we compare the effects of normal adult aging on both the TOL and a more ecologically valid planning task, the Plan-a-Day (PAD) task. There was a reliable decline in TOL planning performance with age, but no significant correlation between age and PAD planning performance. Age-related variance was partly explained by variance in information processing speed and education. It is proposed that in more ecologically valid planning tasks, age changes in processing speed can be compensated for by task-related knowledge. Implications for everyday planning performance by older adults are considered.

Activities of Daily Living↗

PubMed2005

A meta-analytic review of verbal fluency deficits in Huntington's disease.

A meta-analysis of 30 studies with 1,511 participants was conducted to estimate and compare the magnitude of deficits on tests of phonemic and semantic fluency for patients with Huntington's disease (HD) relative to healthy control participants. As has been found for patients with focal frontal cortical lesions (but not for patients with focal temporal cortical lesions), symptomatic HD patients were comparably impaired on tests of phonemic and semantic fluency (rs=.71 and .73, respectively). However, in contrast to patients with focal frontal lobe injuries, fluency deficits did not qualify as differential deficits relative to verbal intelligence or psychomotor speed. Therefore, for patients with HD, deficits on tests of phonemic and semantic fluency do not appear to reflect executive dysfunction but a more generalized cognitive impairment.

Adult↗

PubMed2004

Adult aging and the perceived intensity of emotions in faces and stories.

BACKGROUND AND AIMS: Experience of emotions changes with age: older adults report fewer intense negative emotional experiences, and are less accurate in labelling facial expressions of some negative emotions. However, there is little empirical evidence as to the effect of age on perception of intensity of emotions. This study aims to investigate whether younger and older adults differ in their ratings of the intensity of others' emotions as presented in photographs of faces and descriptions in text. METHODS: Age effects on intensity ratings of emotions (happiness, fear, anger, sadness) from photographs of facial expressions and verbal descriptions of emotions in text were investigated in 91 healthy adult participants. Relationships of these intensity ratings with measures of cognitive ability and current mood were also examined. RESULTS: Older participants perceived lower levels of emotional intensity in sad and happy faces. Compared with the older group, younger adults perceived neutral faces as showing high anger levels. Younger adults also rated protagonists in stories as experiencing high levels of fear. Most of the age differences could be statistically explained in terms of anxiety, depression, and intelligence test scores. CONCLUSIONS: Older adults rate some aspects of emotions portrayed in facial expressions and written text as less intense. This may partly reflect better emotional adjustment with age, as reflected in lower levels of anxiety and depression.

Adaptation, Psychological↗

PubMed2004

The role of semantic knowledge on the cognitive estimation task--evidence from Alzheimer's disease and healthy adult aging.

The current study investigated the role of semantic knowledge on the Cognitive Estimation Task (CET). In an initial experiment, the CET performance of 21 patients with frontal lobe lesions was compared with 21 healthy controls. The CET was found to be sensitive to the effects of frontal lobe lesions. In Experiment 2, 175 participants aged between 18 and 87 years performed the CET to examine the effects of healthy adult aging on the task. No significant age effects were evident. In Experiment 3, 27 patients with Alzheimer's disease (AD) were compared with 27 healthy controls on the CET. AD patients produced significantly more extreme cognitive estimates than the controls. A significant correlation was found between CET performance and performance on the General Knowledge of the World Task, a task intended to assess semantic knowledge. The hypothesis is put forward that healthy older adults are able to use their intact semantic knowledge to compensate for problem-solving deficits when generating cognitive estimates. In contrast, owing to degradation in semantic abilities, AD patients are unable to benefit from semantic knowledge and instead tend to produce bizarre cognitive estimates.

Adolescent↗

PubMed2004

Verbal fluency performance in dementia of the Alzheimer's type: a meta-analysis.

A meta-analysis of 153 studies with 15,990 participants was conducted to compare the magnitude of deficits upon tests of phonemic and semantic fluency for patients with dementia of the Alzheimer's type (DAT) relative to healthy controls. As has been found for patients with focal temporal cortical lesions (but not for patients with focal frontal cortical lesions), DAT patients were significantly more impaired on tests of semantic relative to phonemic fluency (r=0.73 and 0.57, respectively). Thus, since phonemic and semantic fluency are considered to impose comparable demands upon executive control processes such as effortful retrieval, but the latter is relatively more dependent upon the integrity of semantic memory, these results suggest that the semantic memory deficit in DAT reflects a degradation of the semantic store. Also supporting this conclusion, confrontation naming, a measure of semantic memory that imposes only minimal demands upon effortful retrieval, was significantly more impaired than phonemic fluency (r=0.60 versus 0.55, respectively). However, since semantic fluency was also significantly more impaired than confrontation naming (r=0.73 versus 0.61), deficits in semantic memory and effortful retrieval may be additive. Semantic, but not phonemic fluency, was significantly more impaired than measures of verbal intelligence and psychomotor speed. Thus, the semantic memory deficit in DAT qualifies as a differential deficit, but executive dysfunction as indexed by phonemic fluency does not constitute an additional isolated feature of the disorder. Dementia severity was not significantly related to the relative magnitude of deficits upon phonemic and semantic fluency.

Aged↗

PubMed2004

A meta-analytic review of prospective memory and aging.

A meta-analysis of prospective memory (PM) studies revealed that in laboratory settings younger participants outperform older participants on tests of both time- and event-based PM (rs=-.39 and -.34, respectively). Event-based PM tasks that impose higher levels of controlled strategic demand are associated with significantly larger age effects than event-based PM tasks that are supported by relatively more automatic processes (rs=-.40 vs. -.14, respectively). However, contrary to the prevailing view in the literature, retrospective memory as measured by free recall is associated with significantly greater age-related decline (r=-.52) than PM, and older participants perform substantially better than their younger counterparts in naturalistic PM studies (rs=.35 and.52 for event- and time-based PM, respectively).

Adolescent↗

PubMed2003

Inhibitory functioning in Alzheimer's disease.

We present a comprehensive review of studies assessing inhibitory functioning in Alzheimer's disease. The objectives of this review are: (i) to establish whether Alzheimer's disease affects all inhibitory mechanisms equally, and (ii) where possible, to assess whether any effects of Alzheimer's disease on inhibition tasks might be caused by other cognitive deficits, such as slowed processing. We review inhibitory mechanisms considered to play a crucial role in various domains of cognition, such as inhibition involved in working memory, selective attention and shifting abilities, and the inhibition of motor and verbal responses. It was found that whilst most inhibitory mechanisms are affected by the disorder, some are relatively preserved, suggesting that inhibitory deficits in Alzheimer's disease may not be the result of a general inhibitory breakdown. In particular, the experimental results reviewed showed that Alzheimer's disease has a strong effect on tasks requiring controlled inhibition processes, such as the Stroop task. However, the presence of the disease appears to have relatively little effect on tasks requiring more automatic inhibition, such as the inhibition of return task. Thus, the distinction between automatic, reflexive inhibitory mechanisms and controlled inhibitory mechanisms may be critical when predicting the integrity of inhibitory mechanisms in Alzheimer's disease. Substantial effects of Alzheimer's disease on tasks such as negative priming, which are not cognitively complex but do require some degree of controlled inhibition, support this hypothesis. A meta-analytic review of seven studies on the Stroop paradigm revealed substantially larger effects of Alzheimer's disease on the inhibition condition relative to the baseline condition, suggesting that these deficits do not simply reflect general slowing.

Aged↗

PubMed2002

Positive mood and executive function: evidence from stroop and fluency tasks.

Contrasting predictions have been made about the effects of positive mood states on the performance of frontal lobe tests that tap executive functions such as inhibition, switching, and strategy use. It has been argued that positive mood is likely to improve some cognitive processes, particularly those dependent on the frontal cortex and anterior cingulate of the brain. However, there is some evidence that happy mood may impair executive functioning. The current experiments investigated the effects of positive mood on Stoop and fluency tests, which are frequently used to assess executive function. Positive mood impaired performance on a switching condition of the Stroop test, but improved performance on a creative uses test of fluency. The effect of positive mood on an executive task may therefore depend on whether a task is inherently motivating or is impaired by diffuse semantic activation.

Adolescent↗

PubMed2002

The effects of adult aging and induced positive and negative mood on planning.

Changes in executive functions have been found in older adults and also in young adults experiencing positive or negative mood states. The current study investigated the hypothesis that older adults would show greater executive function impairment following mood induction than young adults. Ninety-six participants (half aged 19-37, half aged 53-80) completed a neutral, positive, or negative mood induction procedure, followed by the Tower of London planning task. Significant interactions were found between age and mood such that older adults showed greater planning impairment than young adults in both the positive and negative mood conditions. Emotionally salient events occurring before testing may interfere with executive function in older adults.

Adult↗

PubMed2002

Age and the understanding of emotions: neuropsychological and sociocognitive perspectives.

Sociocognitive approaches suggest that the ability to understand emotions should be well maintained in adult aging. However, neuropsychological evidence suggests potential impairments in processing emotions in older adults. In the current study, 30 young adults (aged 20-40 years) and 30 older adults (aged 60-80 years) were tested on a range of emotional ability measures. There were no age effects on the ability to decode emotions from verbal material. Older people were less able to identify facial expressions of anger and sadness, and showed poorer ability to identify theory of mind from pictures of eyes. The results indicate specific age-related deficits in identifying some aspects of emotion from faces, but no age effects on the understanding of emotions in verbal descriptions.

Aged↗

PubMed2002

Age, executive function, and social decision making: a dorsolateral prefrontal theory of cognitive aging.

Current neuropsychological models propose that some age-related cognitive changes are due to frontal-lobe deterioration. However, these models have not considered the possible subdivision of the frontal lobes into the dorsolateral and ventromedial regions. This study assessed the age effects on 3 tasks of executive function and working memory, tasks dependent on dorsolateral prefrontal dysfunction; and 3 tasks of emotion and social decision making, tasks dependent on ventromedial prefrontal dysfunction. Age-related differences in performance were found on all tasks dependent on dorsolateral prefrontal dysfunction. In contrast, age-related differences were not found on the majority of the tasks dependent on ventromedial prefrontal dysfunction. The results support a specific dorsolateral prefrontal theory of cognitive changes with age, rather than a global decline in frontal-lobe function.

Adult↗

PubMedDate not supplied

Covariates of production and perseveration on tests of phonemic, semantic and alternating fluency in normal aging.

Standard measures of phonemic and semantic fluency, as well as fluency measures that impose additional demands upon set-switching were administered to younger and older adults. No age effect was found for total output on semantic fluency, while older participants generated significantly more responses relative to their younger counterparts on the phonemic measure. However, older adults made significantly more perseverative errors on both these measures. For tests of alternating fluency, only where participants were required to switch between two semantic dimensions, was an age deficit observed. Although the correlation between phonemic repetitions and age remained significant when performance on the Digit Symbol Test or a measure of fluid intelligence was partialled out, age effects for semantic repetitions and semantic alternating fluency were substantially reduced. The age benefit for number of correct responses upon phonemic fluency was significantly attenuated when a measure of crystallized intelligence was entered as a control variable. The theoretical and practical implications of these results are discussed.

Adolescent↗