Stress in middle age could contribute to later dementia

Analysis of post-mortem with and without dementia has found lipopolysaccharide, a component of an oral bacterium (Porphyromonas gingivalis), in four out of 10 Alzheimer’s disease brain samples, but not in any of the 10 brains of people who didn’t have Alzheimer’s.

Gingivitis is extremely common, and about 64% of American seniors (65+) have moderate or severe periodontal disease.

The finding adds to evidence linking gum disease and Alzheimer’s.

We know that traumatic brain injury increases the risk of later developing neurodegenerative disorders such as Alzheimer's disease, but we haven't known why. New mouse studies suggest a reason.

A review of nearly 2.8 million patient cases in Denmark found that the risk of dementia in individuals with a history of TBI was 24% higher than those without a history of TBI, after accounting for other risk factors.

Risk was greater when the TBI was characterized as "severe" — 35% compared to an increased risk of 17% for a single "mild" TBI or concussion.

Moreover, dementia risk increased 33% higher for two or three TBIs, 61% higher for four TBIs, and 183% higher for five or more TBIs.

Survey data from 6,807 Danish older adults (average age 60) in the Copenhagen City Heart Study, has found that being distressed in late midlife is associated with a higher risk of dementia in later life.

The survey measured “vital exhaustion”, which is operationalized as feelings of unusual fatigue, increased irritability and demoralization and can be considered an indicator of psychological distress. Vital exhaustion is suggested to be a response to unsolvable problems in individuals' lives, in particular when being incapable of adapting to prolonged exposure to stressors.

Hearing loss linked to increased dementia risk

A Taiwanese study involving 16,270 adults, of whom half had newly diagnosed hearing loss, found that those with hearing loss had a higher risk of dementia, particularly among those aged 45-64. Six comorbidities (cerebrovascular disease, diabetes, anxiety, depression, alcohol-related illnesses, and head injury) were also significantly associated with a higher dementia risk.

Among the study participants, 1,868 developed dementia during the 13-year study period.

How alcohol increases Alzheimer's risk

A cell-culture study using rodent microglia found that some of the genes affected by alcohol and inflammation are also implicated in processes that clear amyloid beta, suggesting that alcohol may impede the clearance of amyloid beta in the brain.

A large, long-running Finnish study looking at the dietary habits of 2,497 men aged 42-60 has found that a high intake of dietary cholesterol was not associated with the risk of dementia or Alzheimer's disease, even among carriers of the ‘Alzheimer’s gene’ APOE4.

Previous research has found that the effect of dietary cholesterol on serum cholesterol levels is more visible in carriers of APOE4. In Finland, the prevalence of the APOE4 gene variant is exceptionally high and approximately a third of the population are carriers.