In Parkinson's, depression can manifest with symptoms that are common to the disease process (fatigue, insomnia, and difficulty with concentration) which makes diagnosis difficult. The imbalance and change in dopamine, serotonin, and noradrenergic hormones are known to be a primary cause of depression in PD affected people.[10] Another cause is the functional impairment that is caused by the disease.[50] Symptoms of depression can include loss of interest, sadness, guilt, feelings of helplessness/hopelessness/guilt, and suicidal ideation. Suicidal ideation in PD affected people is higher than in the general population, but suicidal attempts themselves are lower than in people with depression without PD.[10][50] Risk factors for depression in PD can include disease onset under age 50, being a woman, previous history of depression, severe motor symptoms, and others.[10]