BENGALURU: Alzheimer’s disease is the most common cause of dementia worldwide. It is primarily due to aging and neuro-degeneration, the contributing factors could be the vascular disease and amyloid. The risk factors associated with Alzheimer’s disease can be both modifiable and non-modifiable. The most important among the non-modifiable risk factors are age and female gender.
The pathogenesis of increased incidence of Alzheimer’s disease in females can be attributed to multiple factors. First of all, the longevity of women compared to men is one of the factors associated with increased incidence in them. Apart from this, census says at the age of 65, women have one in five chance of developing Alzheimer’s compared to men who have one in 11 chances. This difference does not explain the longevity entirely as a sole cause.
Oxidative stress involving mitochondria is an important pathogenic mechanism associated with the development of Alzheimer’s disease. In young females, the reactive oxygen species (ROS) generated is less compared to males and hence they are protected against the amyloid beta toxicity. Studies show that as age advances, the amount of ROS generated is equal to those seen in males. Oestrogen replacement therapy in ovariectomised females leads to decrease in the production of peroxides. This powerful antioxidant mechanism associated with oestrogen could be an important contributing factor.
The structure and functional differences of brain function in men and women may influence the development of cognitive decline. On a structural level, male brain volume is larger than females and on a functional level, the connectivity and blood flow may be higher in the motor and visual cortices in females and parietal association cortex in males.
These differences may impact the development of dementia earlier in females. Some studies show that it may be because of the interaction of the gene with oestrogen. The social roles, opportunities, higher education and income, occupational complexities and complex physical activities are much lesser in women compared to men in several countries worldwide, especially in women of today’s older cohort.
Pregnancy may have an influence on cognitive impairment in certain patients who develop pre-eclampsia. Studies show that pre-eclampsia is associated with mild cognitive impairment. To conclude, the influences on observed gender differences are complex. The gender difference in Alzheimer’s disease is an important area of clinical research.The author is senior consultant, neurologist and epileptologist, stroke specialist, BGS Gleneagles Global Hospital, Bengaluru