Could cognitive impairment from bipolar disorder effect one's grades and overall intelligence?

Impact on function: Until one finds a way to relieve or reduce the symptoms of mental/emotional/behavioral disorders they do indeed have an impact on functioning in many areas of life. Often that is a necessary part of the dx. It's not likely that the innate intellectual capacity would be diminished, but the performance level definitely could. Find effective tx - a combo of cbt talk therapy and meds may be best.