[Depression and frontal dysfunction: risks for the elderly?].Encephale 2009; 35(4):361-9E
Frontal lobe syndromes include reduced activity, particularly a diminution of spontaneous activity, lack of drive, inability to plan ahead, and induce a lack of concern. These last points constitute the executive dysfunction syndrome. That executive dysfunction could be the core defect in patients with geriatric or vascular depression, and might be related to frontal-subcortical circuit dysfunction. Sometimes frontal lobe syndromes are associated with restless, aimless, uncoordinated behavior or even disinhibition, increasing the risks of falls and of malnutrition. Some authors have distinguished between lesions of the lateral frontal cortex, most closely linked to the motor structures of the brain, which lead to disturbances of movement and action with perseveration and inertia, and lesions of the orbital and medial areas, interlinked with limbic and reticular systems, damage to which leads to disinhibition and changes of affect. The medial frontal syndrome is marked by akinesia, associated with gait disturbances, and loss of autonomy. For these reasons, it has been proposed that a subtype of depression, "depression-executive dysfunction syndrome" could occur in late life. This assertion was based on clinical, neuropathological, and neuroimaging findings suggesting that frontostriatal dysfunctions contribute to the development of both depression and executive dysfunction and influence the course of depression. Depressive symptomatology, and especially psychomotor retardation and loss of interest in activities, contributed to disability in depression-executive dysfunction syndrome patients. This study is not restricted to major depression. It examined the relationship of executive impairment to the course of depressive symptoms among a psychogeriatric population with dementia or depression in order to assess the consequences of these pathologies on disabilities of aged persons.
The study was carried out in Limoges (France) during 2006 and 2007. Three hundred and twenty one psychogeriatric outpatients were included after their written agreement. They were assessed using different scales for autonomy, cognition, depression, frontal impairment and these results were compared with the risk of fall, a possible loss of autonomy and a proteino-energical malnutrition. The statistical study was made using the Systat 11 software. The following tests were used: Student Test, Chi(2) test, and the Manova test, which was adjusted to the duration of the disease, the caregiver's age, his/her education level, and level of cognitive impairment. The regression method used was the multiple linear regression method as well as a descending step-by-step analysis.
One hundred and thirty six males (77.3+/-7.09 years old) and 185 females (80.4+/-6.5 years old) were recruited. Patients mainly presented with Alzheimer's disease (n=123) and 65 presented an associated depression, 25 presented vascular dementia, 30 a Lewy bodies dementia, 27 a fronto-temporal dementia. Twenty-seven presented psychosis and 40 a Mild Cognitive Impairment. A control group was composed of 33 persons presumed without psychogeriatric pathologies. Depression associated with an executive dysfunction syndrome increased loss of autonomy, the risk of fall and of malnutrition, especially in the case of cognitive impairment. The multivariate regression analysis step-by-step shows an increasing risk of fall in the presence of a depression-executive dysfunction syndrome. Motivation is altered when the patient is depressed. In demented patients, depression significantly increases behavioral disorders, social and familial relationships, and instrumental acts of daily life. It precipitates the risks of falls and of malnutrition.
The principal finding of this study is that geriatric depression is characterized by impaired executive functioning. In the present study, depressed patients also had a greater tendency to fall and to suffer from malnutrition. Executive processes are fundamental to the daily functioning of depressed older adults, and dysfunction may lead to a lack of compensatory strategies that would improve the outcomes of late-life depression or of increasing dependency as well. In demented patients, depression triggers loss of motivation and executive dysfunction as well.
Depression and executive dysfunction triggers the loss of autonomy, the risk of fall and of malnutrition in elderly patients. The clinical significance of this study is that the delineation of specific executive in depressed elderly patients may facilitate the development of effective treatment interventions, including treatment for geriatric depression.