There are various forms of dementia produced by various causes.
Memory loss is the most prominent early symptom.
The study involved 10 Alzheimer's disease patients and 10 matched controls. Patients were given a battery of motor, somatosensory, and visual tests that required use of either one or both cerebral hemispheres. Tasks were chosen such that subjects with Alzheimer's disease performed normally when using intrahemispheric processing. The same subjects, however, performed poorly when interhemispheric communication was required. The two halves of the brain, although exhibiting certain functional specializat- ions, ordinarily work in an integrated manner to produce the conscious output of the nervous system, namely thought and action.