Parental history of dementia increases risk of dementia, primarily when age at parental diagnosis is <80 years, according to a recent study. From 2000 to 2002, researchers assessed parental history of dementia in participants without dementia. They investigated associations of parental history with risk of dementia until 2015, adjusting for demographics, cardiovascular risk factors, and known genetic risk variants. In addition, they determined the association between parental history and markers of neurodegeneration and vascular disease on MRI. They found:

• Of 2,087 participants (mean age, 64; 55% female), 407 (19.6%) reported a history of dementia in either parent (mean age at diagnosis, 79).
• During a mean follow-up of 12.2 years, 142 participants developed dementia.
• Parental history was associated with risk of dementia independently of known genetic risk factors, in particular when parents were diagnosed at a younger age.
• Accordingly, age at diagnosis in probands was highly correlated with age at diagnosis in their parents <80 years but not thereafter.
• Among 1,161 participants without dementia with brain MRI, parental history was related to lower cerebral perfusion and higher burden of white matter lesions and microbleeds.