Which feature is MOST helpful in distinguishing dementia from severe depression?

Somatic complaints such as anorexia, weight loss and headache are features of both conditions, though more prominent in patients with depression. The behavioural and cognitive functions are affected in both conditions. Poor concentration, poor attention span, poor memory and social withdrawal are encountered in both. Grasp reflex and other primitive reflexes indicate neuronal loss in the frontal lobe, which does not occur in depression. A positive response to antidepressant treatment is a reliable sign in our of depression