A large majority of brain tumor cases show definite mental symptoms. Most frequent are mental dullness, somnolence, hebetude, slowness in thinking, memory failure, irritability and depression, although a tendency to facetiousness is sometimes observed. Episodes of confusion with hallucinations are common; some cases express suspicions and paranoid ideas.

The diagnosis must rest in most cases on the neurological symptoms, and these will depend on the location, size and rate of growth of the tumor. Certain general physical symptoms due to an increased intracranial pressure are present in most cases, viz.: headache, dizziness, vomiting, slowing of the pulse, choked disc and interlacing of the color fields.