Factors predisposing to dementia
Dementia is the inability to perform normal functions due to impaired reasoning, thinking and memory. Currently, the cumulative risk of developing dementia is 20 % and with increasing aging, about 50 % of the population will eventually be affected. The STAGED project team obtained data from five longitudinal studies on aging — three from the Swedish Twin Registry and two from the Aging Research Centre . Studies revealed that factors such as timing and frequency of stressful life events, genetic susceptibility and telomere shortening can hasten the onset of dementia. One of the earliest signs of dementia is the decreased volume of the hippocampus, a part of the brain associated with memory and spatial functioning. A key finding is the fact that stressful life events experienced before the age of 18 affect the hippocampus. In contrast, stressful life events experienced later in life only temporarily increased amygdala volume. Amygdala is a part of the brain that is linked to emotions and stress sensitivity. Experiencing two or more stressful life events increases cardiovascular risk. This in turn increases the risk for dementia onset over the next 15 years — three times sooner than in individuals without such stress. Telomeres are repetitive nucleotide sequences present at the end of chromosomes. Interestingly, analysis revealed that people with a shorter telomere length who experienced two or more stressful life events had higher memory decline over time. The genes — FKBP5 and NR3C2 are involved in mood disorders, stress sensitivity, and cognitive decline. People who experienced two or more stressful life events and had single nucleotide polymorphisms in these genes showed higher memory decline over time. In comparison, people having either but not both of these factors, did not experience such memory decline. STAGED outcomes provide deeper insight into factors facilitating dementia onset. Healthcare providers and policy makers can now utilise this data to identify high-risk individuals and optimise the clinical management of such individuals. Onset of dementia could thus be delayed or the severity of symptoms managed for better quality of life.
Keywords
Risk, dementia, ageing, life events, psychosocial stress, genetic susceptibility, telomere shortening, hippocampus, stress sensitivity, cognitive decline
