There is also a characteristic paranoid form of senile psychosis. Delusions of suspicion and jealousy are common in these cases. They usually develop persecutory trends and often exhibit hallucinations of hearing. They sometimes show partial disorientation and gaps in the memory. The mood is usually irritable and often anxious. There is very likely to be a disturbance of sleep and often signs of physical enfeeblement. There may be neurological symptoms caused by the arteriosclerotic complications, such as headache, pupillary changes, tremors of the tongue and disturbance of the reflexes. Tremors are also shown in the writing. Paraphasia occurs and there may be sensory aphasia or apraxia. In severe cases of senile dementia Kraepelin expects to find definite lesions at autopsy. The brain weight is always decreased, sometimes to a very striking degree. The volume of the brain is reduced and the ventricles enlarged. The cortex is diminished in thickness, the frontal region being most affected. The parietal region may be involved, but not to any such extent as in general paresis. There may be localized areas of atrophy. Pachymeningitis and hemorrhagic membranes are often found. The microscope shows a proliferation of the glia cells and there is often some disturbance of the layering of the cortex. Cell alterations appear, with fatty degeneration, some neurones showing little more than a darkly colored nucleus. The glia cells are enlarged. There should be no marked changes in the vessels. Fatty changes in the ganglion cells are very noticeable. There is also some loss in the tangential fibres.