Today we are experiencing a change in our attitude regarding deficiency and disability. As the population grows older, new therapies have to be found to treat the cognitive decline that occurs with age. The generalization in the use of computers has opened the door to information technology (I.T.) solutions for cognitive rehabilitation. Games that, previously, were designed exclusively for entertainment are now considered as valuable tools for "brain-training". Two complementary cognitive interventions using computer games are being currently used. Computer games can be used for training specific cognitive skills extrinsically or as a neurofeedback for the intrinsic enhancement of brain abilities. Here we use both approaches in an integrated I.T. system for the cognitive rehabilitation of elderly subjects. Using a novel approach for the multivariate analysis of EEG signals using graph theory, we are able to describe the current brain state in real-time while the subject is receiving a cognitive intervention with a computer game. This information is used to calculate a cognitive ability score (CAS) that is used to build a specific cognitive training for the subject's special needs. The system can be used both at home and at the hospital, so a systematic training can be achieved. Tools such this one can be extremely useful in a near future as rehabilitation system for the elderly population.