Biomedical subjects
Christian Derouesné
Publications and source records attributed to Christian Derouesné.
[Psychobehavioral disorders in severe dementia].
Behavioral and psychological symptoms of dementia (BPSD) are not included in the diagnostic criteria for dementia or in the assessment tools for grading its severity. However, they constitute a major part of the caregivers' burden and the main cause for institutionalization. They are, for one part, the direct consequence of the brain lesions, but, for another part, they result from the psychological reactions of the patients to their cognitive deficits or their relational difficulties with their family or carers. Despite speech disorder and mind disruption, patients with severe dementia still have a psychic and relational life, which is expressed through BPSD. Many BPSD are of short duration and can be improved by a better understanding, psychological and behavioral approach. However, psychotropic drugs are often useful or necessary, but, due to the frailty of the patients with severe dementia, their use should be very cautious.
[Vascular dementia: the dubious disease].
Vascular dementia is not a disease or even a clearly defined disorder. It is a construct, which brings together very heterogeneous disturbances at the clinical, pathological and etiological levels. Due to the absence of neuropathologic diagnostic criteria, the frequency of associated degenerative pathology (mainly of Alzheimer type), and the heterogeneity of the construct, its clinical diagnosis remains questionable using various diagnostic criteria. The concept of vascular cognitive impairment (VCI) has been proposed as a substitute for vascular dementia to provide some clarification about the relationship between ischemic brain lesions and cognitive dysfunction. Its main interest is to allow diagnosis and treatment of minor cognitive deficits associated with ischemic brain lesions before the occurrence of dementia. Clinical and neuropsychological manifestations of VCI are of fronto-subcortical type, quite distinct from those of Alzheimer's disease. From a practical point of view, the main point is to find out and to treat the vascular risk factors which cause cognitive deficits by themselves or increase those associated with Alzheimer's disease.
[Neuropsychology of action and body schema].
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[Sexuality and dementia].
Sexuality, love, companionship and intimacy remain important parts of life in older people and demented patients. The most frequent sexual disorder reported by spouses of patients with dementia is sexual indifference related to apathy and blunted affect. Increase of sexual demands is rare and many behaviors considered as inappropriate or expressing hypersexuality actually express affective needs or result from cognitive disturbances. Permanence of sexual activity is most often a factor of adjustment for married dementia sufferers and their caregivers. However, some sexual behaviors are stressing for the spouses, mainly women spouses. In nursing homes or long term care facilities, expressing sexuality by demented subjects and dealing with inappropriate sexual expression are source of concerns for the nursing staff, other residents, and families. Information about sex and dementia and a psychobehavioral approach can decrease the strain of families and caregivers.
Deficit of preparatory attention in frontotemporal dementia.
We studied preparatory attention in patients suffering from frontotemporal dementia in the beginning stages of the disease, using an experimental test developed by LaBerge, Auclair, and Siéroff (2000). In this experimental test, a distracter can appear while subjects have to prepare to respond to a simple target. The probability that a distracter can appear in a trial is varied across three blocks. Normal controls show an increase of response times to targets (slope) as a function of the distracter probability, preparatory attention to the target is reduced by the increase of the distracter probability. Patients suffering from frontotemporal dementia show a slope of response times which is more than twice as large as the slope obtained by their matched controls. Such an abnormal increase of response times to targets is interpreted as a deficit in preparatory attention. Patients also show more omissions than controls. We suggest that this deficit in preparatory attention is related to the frontal lesion presented by the patients and can result in higher distractibility, a symptom frequently encountered in these patients.
[Apathy: a useful but limited concept].
In the nineties, Marin proposed to define apathy as a clinical syndrome due to a lack of motivation. The syndrome is characterized by a diminished goal-directed overt behaviors, a lack of interest or concern for social and personal activities and a lack of responsiveness to positive and negative events. Apathy is clearly distinct from depression and can be observed in many conditions, in healthy people as well as in psychiatric disorders such as depression or schizophrenia. It is very common in patients with brain lesions involving the frontal lobes, the right hemisphere, but also in degenerative diseases such as Alzheimer's disease. Motivation, considered as the source of apathy by Marin, is not a simple construct. It refers to a complex set of multiple affective and cognitive processes. However, it is considered, either in an energetic acception, as a single quantitative variable, a force which impulses action but not direct behavior or, in a more specific acception, as the factor which direct behavior towards specific actions. The description of apathy by Marin and the scales designed to its assessment, are based on the first acception. The term apathy is only descriptive, such as those of dysphasia or anosognosia. They do not allow to study the mechanisms underlying the motivation disorders, essential process for the management of apathetic patients. A tentative qualitative approach to assess motivation disorders is proposed, using a semi-structured interview. However, it should be stressed that motivation can not be directly assessed: motivation is a concept to explain some behavior disorders and an inference from the study of behavior.
[Memory complaints in 200 subjects meeting the diagnostic criteria for age-associated memory impairment: psychoaffective and cognitive correlates].
We studied 200 subjects recruited by general practioners and meeting the seminal criteria for the age-associated memory impairment construct (AAMI). These criteria did not allow to select an homogeneous population. Three groups could be distinguished. First, 18 subjects had apparent psychoaffective disturbances, mainly related to anxiety. Second, 41 subjects had lower memory performance than the other subjects and could be classified as severe AAMI or late-life forgetfulness, former constructs similar to the present construct of mild cognitive impairment (MCI). A large majority of subjects (n -/+ 141) had no apparent psychoaffective disturbances and normal memory performance. They could correspond to the proper AAMI construct. Actually, two subgroups could be distinguished in these subjects. Half of them had low cognitive complaints, assessed by the cognitive difficulties scale, compared to those formerly found in a population of 1349 subjects aged over 50, studied by GP, but not specifically recruited on the presence of memory complaints. These subjects could be considered as quite normal subjects. The other half of AAMI subjects had higher scores of memory complaints and more psychoafective disturbances than the subjects of the first group. No relationship was found between subjective complaints and memory performance in the total population as well as in any subgroup. The main correlate of memory complaints was the score on the Zung anxiety scale in the total population, the LLF and the AAMI groups. This study do not support the existence of a specific category of aged subjects intermediate between normal subjects without subjective memory decline and patients with MCI or incipient Alzheimer's disease. Memory complaints appear to be related to psychoaffective disturbances even in subjects with low memory performance.
[On the disclosure of the diagnosis of Alzheimer's disease].
In contrast to the legal or professional instructions, many French or European physicians remain reluctant for disclosing the diagnosis of Alzheimer's disease to their patients. The reasons put forward for not telling the truth appear to be no more justified. The wish to protect the patient from negative reactions as well as the argument that the patient is not able to understand the significance of the diagnosis are not clinically grounded. Moreover, the situation is presently modified by new circumstances: the early diagnosis of the illness in most cases and the availability of active drugs and support measures. Therefore, it appears necessary to more deeply understand the difficulties met by the patient, the family but also by the physician in the process of disclosure of the diagnosis of Alzheimer's disease. In this purpose, some practical suggestions are presented to facilitate the dynamic of the communication between physician, patient and family.
[Planning and activities of daily living in Alzheimer's disease and frontotemporal dementia].
OBJECTIVE: To study the relationship between the disturbances in activities of daily living and the scores on tests assessing planning activities in frontotemporal dementia (FTD) and Alzheimer's disease (AD). METHODS: Eleven patients with FTD were compared to 11 patients with AD and 29 healthy controls. Cognitive status, evaluated by the Dementia Rating Scale (DRS) and the Mini Mental State Examination (MMSE) was identical in the two groups of patients. Activities of daily living were assessed by three questionnaires completed by the main caregiver: (1) the Cognitive Difficulties Scale (CDS); (2) the NADL, a composite scale including the Physical self-maintenance scale (ADL) the Instrumental activities of daily living (IADL) the social activities scale, (SADL); (3) the Dysexecutive Questionnaire (DEX) from the Behavioural Assessment of the Dysexecutive Syndrome. Planning abilities were assessed by the tower of London and three tests from the BADS: the key search, the zoo map and the six elements. RESULTS: No quantitative differences were found between FTD and AD patients in daily living activities disturbances or scores on planning tests. Both were closely related to the global cognitive performance assessed by the DRS or the MMSE but no clear relationship was found between them. The scores on the tower of London were not correlated to those on the tests from the BADS. CONCLUSION: Neither assessment of activities of daily living or scores on the planning tests could differentiate FTD from AD. Planning appears as a multidimensional construct poorly assessed by the usual assessment tools.
[The echo of vascular lesions in the brain].
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[The role of aluminum in the genesis of Alzheimer's disease: relax in the absence of sufficient proof in the current state of our knowledge. Neurotoxicity of aluminum: doubt for highly exposed populations].
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[Frontotemporal lobe degeneration: a rare disease, but malignant].
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[Fluctuations of cognition in Lewy body dementia are different from those observed in Alzheimer's disease].
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[Cognitive disorders at the onset of Huntington disease].
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[Depression and dementia].
Data from the literature devoted to the relationships between dementia and depression are controversial on account of numerous methodological biases (community studies or from neurological or psychiatric departments), categorical versus dimensional approaches and variability of assessment tools for depression, aim of the study (depression versus dementia or versus Alzheimer's disease, AD). The difficulty to discriminate depression from AD is largely overestimated due to the confusion between depression, depressive symptomatology and apathy. The distinction is greatly facilitated by taking into account the qualitative differences of the memory deficits and cerebral imagery. Distinction of depression from frontotemporal or subcortical dementias could be much more difficult. Relationships between depression and AD are controversial. Most reports of depression as a risk factor for AD in the subsequent years, actually describe depressed symptomatology linked to apathy in preclinical AD. However, some studies found a relationship between AD and depression occurring more than 10 years before the onset of AD symptomatology, suggesting some common risk factors. The so-called symptoms of depression in AD are more related to apathy and affective disturbances than to dysphoria. The frequency of major depressive episode (MDE), greatly varies according to studies, but the frequency of suicide is low. Depression in dementia is related to neurobiological factors as well as to psychological mechanisms. Therefore, its treatment should associate antidepressant drugs and psychological support directed to the patient and family.
[Semiology of executive functions].
The term "executive functions" was coined to describe the abilities of planning, monitoring and controlling activity, specially in novel tasks. These functions have been associated with the activity of the frontal lobes. Dysexecutive function results in impaired inhibition of non-relevant information, flexibility and updating mental representations which can be observed in behaviour and in executive tests. The assessment of executive control is necessarily indirect and executive tasks always include non-executive components. Therefore, disturbances in executive tests are neither sensible nor specific for frontal lobe dysfunction. The results on different executive tasks are frequently dissociated in the same patient and are weakly correlated with the behavioural disturbances. Thus, the results on executive tests should always be compared to behavioural assessment.