Infections are a cause of encephalopathy. Many types of bacteria, viruses, and fungi can cause encephalitis by infection and inflammation of the brain tissue or of the meninges (meningitis) that line the brain and spinal cord.
A value of zero indicates that there is no relationship between the two variables. If the correlation coefficient of two variables is zero, it signifies that there is no linear relationship between the variables. However, this is only for a linear relationship; it is possible that the variables have a strong curvilinear relationship.
In case of low R square values the coefficients of the variables can be checked. If the coefficient of a variable is highly significant that means it is an important variable yet the overall selection of all the variables is not good enough to explain the variability of dependent variable.