chemo and confusion

My Dad is on his third shot at chemo after an esophagectomy in Nov. 03. The first two were too toxic for him. This one - something derived from the ewe plant - seems to be easier on him physically, but mentally it is taking a beating on him. He is extremely fatigued, confused and occasionally paranoid. He is taking anti-depressants and an MRI showed no cancer or other physiological problems in his brain. It may be the extreme fatigue is causing the confusion, but I would really like to know if any of you have similar experiences with this type of reaction? It's really taking a toll on my Mom, who is is primary caregiver. Thank you for any information.