الفهرس 
Introduction
Aim of the workOnly 14 pages are availabe for public view
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Abstract
Researches over decades consistently show that peoples who have high total serum cholesterol levels during midlife are on average more likely to develop dementia relative to those with normal TC, which also is accepted by the social norms and believes. But this concept has changed over years with many studies that advocate for the beneficial effects of cholesterol on cognition, placing us in uncertainty about the role of cholesterol in dementia and cognitive dysfunction.
In our study, we were guided by the Chinese study carried by Cheng and Co-worker (Cheng et al; 2014) to find if there is a relation between total cholesterol and cognitive performance in older peoples in the presence of another risk factor, Homocysteine. But what they found in their study that, low and high TC is deleterious to the cognitive function in normal Hcy levels is somewhat against our one.
We find only a direct correlation between high total TC (>181 mg/dl) and cognitive scores, in the presence of normal Hcy levels, and below this level (181 mg/dl) there is no a relation between them.
But there is a small difference between the optimal levels of cholesterol that both of us recommended, according to us 181 mg/dl and in the Chinese study is 170 mg/dl is favorable. However, we still find a significant correlation between those above 200 mg/dl and cognition, this outcome may be changed if huge number of participants, follow up and wide range of ages were included.
Another significant correlation was observed between cognitive score and HDL. Like many other studies, we found that HDL may have a protective role in neurodegenerative diseases, not only in the cardiovascular diseases.
Overall we can’t assert that the effect of cholesterol on cognition is homocysteine dependent, as the entire 40 participant had normal Hcy levels, only one had high abnormal Hcy where a correlation couldn’t be done.