Cognitive dysfunction such as impairment of memory, attention, spatial and verbal functions plays important role in etiopathogenesis and clinical picture in neurodegenerative disorders. There are related with structural and functional abnormalities of different region of the brain connected with these cognitive processes. Cognitive dysfunctions caused severe functional and social disabilities of the patients. The neuroimaging methods such as F-MRI, or PET scan are very useful in diagnosis of structural and functional changes in the brain in neurodegeneration diseases, e.g. Parkinson's or Alzheimer's diseases. Neuroimaging during cognitive stimulations show different brain activation in patients with schizophrenia or neurodegenerative disorders in comparison to healthy subjects. F-MRI show increase of prefrontal cortex activation during n-Back test performance in healthy controls, while in patients with schizophrenia and Alzheimer disease this effect was not noted. In schizophrenia patients after treatment with risperidone (but not with haloperidol) the normalization of activation in different brain area was observed.

F-MRI assessment during N-back test (0 - back and 1-back tasks), encoding and recognition, visual discrimination performed in 9 patients with Alzheimer's Disease (AD) and 9 healthy subjects show abnormal activation in patients with AD. Among 9 patients with AD 5 were treated with rivastigmine, 4 received placebo. Cognitive improvement was observed after 3 months of treatment with rivastigmine - the same time fMRI showed an increase in brain activity in regions involved in attentional processes. This indicate that neuroimaging methods during cognitive stimulation may be useful in cognitive assessment in CNS disorders and in assessment of drug effect on cognition.