Another significant element is that the brain of people considered as normal on a cognitive level conceals neuropathological signs perceived as characteristic of dementia. “The older people become, the more their brain is affected by such signs”, Martial Van der Linden explains. “Beyond 85 years old, there is about the same number of amyloid plaques in the brain of dementia sufferers as in the brain of people who aren’t.” In addition, Swedish researchers have shown that the areas of the brain affected by so-called normal aging are the same as those affected in the case of dementia.

Assuming the complex nature of cerebral aging

Furthermore, Martial Van der Linden points out that the brain of the large majority of people diagnosed with Alzheimer's disease shows signs of suffering from various types of vascular injuries. Therefore, some authors suggest that amyloid cascade or the phosphorylation of tau protein (neurofibrillary tangles) aren’t causal factors of Alzheimer’s disease, but an adaptive mechanism or a protective response of the brain to injuries that various mechanisms would have generated. “Consequently, we should beware of seeking to eliminate amyloid plaques or neurofibrillary tangles, as it may potentially accelerate the neurodegenerative process”, underlines Martial Van der Linden.

Even if clinical trials have begun, such drugs with a curative vocation (or just with a deleterious effect…) aren’t available in clinical practice, because research fails to make progress. Opponents to the biomedical approach to cerebral and cognitive aging would exclaim that it is completely logical.  As for symptomatic drugs – cholinesterase inhibitors and memantine -, they have no real efficacy as regards autonomy and quality of life in people diagnosed with Alzheimer’s and they don’t improve the cognitive functioning of individuals diagnosed with Mild Cognitive Impairment.

For all these reasons, Martial Van der Linden and Anne-Claude Juillerat are among an ever-increasing number of people who believe it is necessary to reintegrate benign or problematic manifestations of cerebral and cognitive aging into the more general context of aging. In their opinion, we should stop focusing on the eradication of a pathogenic process specific to each “disease” (dementia) considered as a distinctive disease so that we can rather reason in terms of risk and prevention factors. “Nevertheless, cerebral aging is inevitable and prevention will just delay the onset of problems or lessen their extent”, our interviewee insists.

The authors of Penser autrement le vieillissement don’t dispute the value of neurobiological research, but favour research that recognises the full complexity of the phenomena. Multiple risk factors likely to emerge at different ages in life should be taken into account if we consider that “at an advanced age, the fragility of brain cells means that they are vulnerable to all sorts of negative influences”.

What influences? Besides a possible genetic vulnerability, recent studies have revealed a whole variety of factors, which may well pave the way for preventive actions. For instance, while several pieces of research, including that of Aron Buchman(3) and his team at Rush University in Chicago, have shown that a low level of physical activity increases the risk of being diagnosed with Alzheimer’s disease, many works emphasise the benefit of physical activity on cognitive functioning.

(3) Buchman, A.S. et al. (2012). Total daily physical activity and the risk of AD and cognitive decline in older adults. Neurology, 78, 1323-1329.