The Mediterranean diet is an eating pattern that is culturally rooted and transmitted by eating habits learned from previous generations.
The older population have followed these customs throughout their lives and been less influenced by the Westernization of their diet. This may be an important reason to explain the high MEDAS score found in this population, when currently the score for the Spanish population stands at around 6.3 (9). León-Muñoz et al. (9) considered that the MEDAS score using cutoffs > 9 defines a strict adherence to the Mediterranean diet, while the use of cutoffs > 7 denotes a modest adherence.
The elderly population in the study had very high mean MEDAS scores (> 9). However, the results were quite different when the cutoff used in the MEDAS was modified to 7. It is interesting to note that some results observed in the answers to the 14 MEDAS questions may not reflect the real situation. For example, only 41.8% of older people met the goal of consuming legumes at least three times a week.
However, the more detailed answers on food consumption indicated that most of the population frequently consumed legumes (twice a week). A similar situation occurred with the results for wine consumption. Most participants considered wine consumption to be beneficial for the health and had routinely consumed wine throughout their adult lives. However, they had abandoned or reduced their intake in recent years due to the greater prevalence of disease and the increased necessity of consuming medicines, some of which interacted with alcohol. both examples it can be said that the consumption of legumes and wine were two eating habits that were deeply-rooted in this population.
In summary, oldest people still adhere to the main features of the Mediterranean diet pattern, such as high consumption of olive oil as the main source of fat, a high consumption of fish, low glycemic fruits and foods with added sugars, a moderate wine intake, and low consumption of red meat. Cognition involves a variety of domains, and age-related decline varies considerably across these cognitive domains and between individuals.
The cognitive functions that are most affected by ageing –independently of Alzheimer’s and other dementias– often relate to attention, memory, perception, and executive function (13). Most of the population studied did not present cognitive limitations evaluated with the MMSE.
These results were similar (14) –and in some cases higher (15-17)– to those found in other studies. It is worth noting that the over 90y were the age group without cognitive limitations. Similar results were found in the Octabaix study (14). The population study had no depressive problems measured with the GDS. Depression during aging is an important public health problem, and causes suffering to many who go undiagnosed (6).
Often neither the elderly themselves nor the healthcare providers recognize the symptoms in the context of the multiple physical problems affecting many elderly people (6). Certain depressive symptoms like low mood may be less prominent than others such as loss of appetite, sleeplessness, lost of interest and so on. Studies of depressed adults report that those with depressive symptoms –with or without a depressive disorder– have poorer functioning than non-depressed adults, and could function similarly to or worse than adults with chronic medical conditions (6,18).
Depression is common in later life, but methodological differences between studies preclude firm conclusions about cross-cultural and geographic variation (19). Depression, decline in cognitive function and problems in nutritional status are common in aging (19). In this study of the relationship between cognitive status and depressive symptoms and the degree of adherence to the Mediterranean diet pattern, we observed that the cognitive function and quality of the diet were positively related. However, no relation was observed with the depressive symptomatology.
Numerous studies have found a relationship between reduced cognitive decline (20) and lower risk of clinical depression with a greater adherence to the Mediterranean diet (18) and a higher quality of life (21).
Skarupski et al. (6) reported that greater consumption of the characteristic food groups in a Mediterranean-based diet was associated with a lower likelihood of depressive symptoms in older adults over time. Diet influences the physiological processes that may be involved in the development of depression in different ways, such as inflammation, oxidative stress or hormonal factors (6).
In contrast to several other non-communicable diseases, the preventive potential of diet in regard to depression is a relatively new research area (5). A recent review study (3) determines that dietary patterns may have an influence on the onset of depression, although the relationship is unclear. The possible role of lifestyle-related factors has been proposed for age-related changes in cognitive function, pre-dementia syndromes and cognitive decline of degenerative or vascular origin. Among these factors, the type of diet (amount and type of food) and the socio-cultural habits related to eating habits could be important in the impairment of the cognitive and affective state (19). Féart et al. (2) reported that stricter adherence to a Mediterranean diet was associated with slower MMSE cognitive decline, but not consistently with other cognitive tests; and not with risk for incident dementia (2).
The Mediterranean diet combines several foods and micro- and macronutrients already proposed separately as potential protective factors against dementia and pre-dementia syndromes. The Mediterranean diet can be linked to mental health outcomes via a high number of dietary constituents such as B-vitamins, antioxidants (nutrients and bioactive compounds) and fat composition –namely a high content in unsaturated fatty acids (mono- and poly-). Several foods such as legumes, nuts and fish are important contributors to polyunsaturated fatty acids, which may be involved in the neurodegenerative process (22-24).
A clear reduction of risk for cognitive decline has been found in population samples with elevated fish and olive oil consumption and a high intake of monounsaturated and polyunsaturated fatty acids, but not when the disease has already taken over (7). Epidemiological studies indicate a higher risk of cognitive decline in people with low w-3 fatty acid intake, although the available evidence does not prove that polyunsaturated fatty acid supplements can protect against cognitive decline or dementia (25). These issues still require clarification.
Nonetheless, there is much experimental evidence pointing to the beneficial role of consuming w-3 fatty acids on the development of cognitive and emotional impairment. Legumes, vegetables and fruits are an important source of vitamins and natural antioxidants.
The limited epidemiological evidence available on fruit and vegetable consumption and cognition has generally highlighted the protective role of these foods against cognitive decline and dementia. In summary, most people of this elderly group showed a very high adherence to the Mediterranean diet pattern, and did not present cognitive limitations. According to this study dietary habits appeared to be related with cognitive limitations but not with depressive symptomatology; however, efforts to decrease the prevalence of depression in the elderly should target risk factors.
Prevention appears to require improvements in physical activity, diet and other lifestyle factors. The Mediterranean diet pattern includes a balanced combination of foods and a healthy lifestyle that positively affects the quality of life of the elderly.