The contribution of the occupational activity, from the neurological point of view,
in the improvement and maintenance of the mental faculties, with reference to Alzheimer's disease
Professor of Neurology, School of Medicine, University of Thessaloniki

Intellectual activity, productive work and systematic of physical activity, increase the neuronal plasticity and ameliorate the mental condition in aging, mild cognitive impairment and early stages of Alzheimer's disease. It is well known that during the mental and physical activity spines on the dendritic branches receive the majority of excitatory synaptic connections in the brain. The synaptic density, the magnitude of the dendritic arborization and the capacity of the creation and projection of new dendritic spines, on the other hand, play a crucial role in expanded synaptogenesis and in dynamic neuronal plasticity. Altered dendritic spines are a substantial characteristic of aging and debilitating diseases of the brain being at the same time the intrinsic cause of the accompanying neurological disturbances. Newly formed filopodia decrease in length and frequency, in advanced aging and they become rare in early cases of Alzheimer's disease, in which the synaptic density decreases dramatically on the secondary and tertiary dendritic branches. Although the cause of Alzheimer's disease remains enigmatic, in spite of the continuously ongoing research on the field, there is, a substantial body of increasing evidence, which pleads in favor of the possible implication of mitochondrial dysfunction in the pathogenesis of several late-onset neurodegenerative disorders, including Alzheimer's disease. Mitochondria are vital organelles, for the maintenance of cell's homeostasis and viability, by virtue of providing most of the energy for the cellular processes. It is important that mitochondria play a critical role in maintaining cellular calcium homeostasis and cellular signaling cascades for both apoptotic and necrotic cell death pathways. Normally, the number of mitochondria in dendrites correlates with synapse development and may play an important role in the morphogenesis of the spines, as well as in the synaptic plasticity. The contribution of the occupational activities, either in the intellectual field or in the physical one is of essential importance in maintaining a continuous influx of information in the brain, which increases the excitatory input to dendritic spines. The role of continuous mental and physical activity in improving the function of the neuronal circuits in the frontal, parietal, temporal and occipital lobe is well documented in clinical cases as well as in experimental models. The occupational activity on the other hand may improve at the same time the harmonization of the collaboration of the various functional centers in the cortex of the lobes of the brain hemispheres by the creation newformed connecting neuronal circuits, new tracks and new long neuronal pathways. A substantial body of evidence, derived from population-based follow up studies, suggest that occupational complexity is related to lower risk of dementia even in cases of low education. Low education has been associated with high risk of Alzheimer's disease, since it is also related, in the majority of the cases, with low or rare professional occupation or with hand work exclusively, without any further intellectual expectation. In treating Alzheimer's disease, occupational therapy plays a fundamental role in ameliorating the cognitive, the physical and the emotional condition of the patients, since meaningful activities, occupational attainment and environmental modification give a dynamic dimension in the everyday life of the patients, stimulating and motivating his higher mental faculties. It is well known that pharmaceutical treatment of the Alzheimer's disease has always a limited in time beneficial effect, lasting six or nine monthes in the majority of the cases. In contrast, continuous occupation within the limits of the patient's capacities and continuous education inducing mental enhancement may be beneficial for longer period of time, increasing the self-esteem and ameliorating, at the same time, the quality of the everyday life of the patient. Encephalos 2010, 47(4):159-169.

Key words: Occupation, neuronal plasticity, dendritic spines, Alzheimer's disease.