Risk factors for mild cognitive impairment and progression from mild cognitive impairment to dementia are not the same for men and women.
Identifying the risk factors that cause mild cognitive impairment (MCI) to progress to dementia can help determine which patients might benefit from treatment, Sylvaine Artero of the Institut National de la Santé et de la Recherche Médicale (INSERM) U888, Montpellier (France), and colleagues reported. Previous studies have addressed the risk factors for progression from MCI to Alzheimer's disease and dementia, but most of those have not involved a general population and have not addressed gender-specific factors.
To determine the gender-specific factors that predict progression of MCI to dementia, the investigators recruited 6,892 community-dwelling adults aged 65 years and older and followed them for 4 years (average age 74 years; half were women). The study was based on a large multicenter prospective study on brain aging sponsored in part by Sanofi-Synthelabo.
A total of 2,882 participants (42%) met the criteria for MCI at baseline. Over the next 4 years, 189 were diagnosed with dementia, 1,626 maintained MCI, and 1,067 returned to a normal level of function (J. Neurol. Neurosurg. Psychiatry 2008 May 1 [doi:10.1136/jnnp.2007.136903]).
Overall, 8% of men with MCI developed dementia, vs. 6% of the women, but women were significantly less likely than men to return to normal cognitive function (36% vs. 39%) and significantly more likely to maintain a diagnosed cognitive disorder over the 4 years (58% vs. 53%).
In a multivariate analysis, older age significantly predicted progression to dementia in men and women.
In men, progression from MCI to dementia was more than three times as likely if they had the APOEϵ4 allele, and more than twice as likely in those with a history of stroke, a low level of education, or difficulty with daily activities as measured by the Instrumental Activities of Daily Living scale (IADL). In women, progression from MCI to dementia was more than three times as likely if they had IADL deficits and more than twice as likely if they had the APOEϵ4 allele, a low level of education, or subclinical depression. And the odds of progressing to dementia were almost twice as high in women who took anticholinergic inhibitors (odds ratio 1.8).
Predictors of progression from MCI to dementia in both men and women in a less rigorous, univariate analysis included the APOEϵ4 genotype, hypertension, diabetes, age, a low level of education, low intelligence, subclinical depression, stroke, social isolation, and difficulty with at least IADL.
“MCI cases in the general population can be differentiated by a much larger number of sociodemographic and clinical factors than previously observed,” the investigators wrote. “These findings support the notion that MCI is a common end point to multiple etiological pathways which are not the same for men and women.”
The study was limited by a lack of analysis of MCI subtypes and by a short follow-up, which may account for the relatively low dementia rate, the investigators said. However, clinicians may be able to use the diverse risk factor data to develop gender-specific clinical interventions, they noted.
The investigators said they had no financial conflicts to disclose.