Now aged 34, Peter has been diagnosed as having multiple sclerosis for the past six years. His first symptom was the paralysis of his right arm. Loss of function developed over several days and then slowly improved. A year later both the right arm and leg were severely affected. This time the symptoms persisted and he was left with an ataxic gait and a loss of power in his arm. Shortly afterwards, Peter reported having persistent double vision and although this disappeared, a diagnosis of multiple sclerosis was made. Three years later, both Peter and his wife noticed that he was having difficulties remembering things. His cognitive problems precipitated a referral for neuropsychological testing. On the WAIS, Peter is found to have an IQ of 107 and on the WMS, an MQ of 93. He has noticeable problems with the Paired Associate and Logical Memory subtests.