The discovery of a link between genetics, age and late-onset dementia could help men identify their risk of developing the disorder later in life.

In research published in the August edition of the journal Neurology, Monash researchers Professor Kim Cornish and Dr Darren Hocking led a team which examined impulsivity, attention and working memory skills of men aged 18 to 69 years, who were all carriers.

Men who are carriers of the FMR1 (Fragile X Mental Retardation 1) gene may be at high risk of developing severe dementia as they age, despite having no obvious symptoms earlier in life.

Fragile X Syndrome is the leading inherited cause of intellectual disability and the most common known genetic cause of autism.
The FMR1 gene occurs in two stages: as a small-medium expansion (carriers) and as a large expansion. Those with the large expansion will have Fragile X Syndrome (FXS) and experience the full effects.
Approximately one in 250 women and one in 800 men will be carriers of the FMR1 gene. For many years, those who carried the gene were assumed to be unaffected by any of the challenges faced by those with FXS.

The men were tested for their ability to phase out irrelevant information as well as actively store short-term information. These core brain functions decline with late-stage dementia.

The research found that carriers of the gene who were at the upper end of the medium expansion were more likely to have problems with inhibition and remembering materials, demonstrating cognitive dementia symptoms, whereas those who had expansions just within the medium range appeared risk-free. [continue reading…]