This patient has Alzheimer's disease, and likely has hydrocephalus ex vacuo: enlargement of the ventricles due to cortical atrophy.
Patient's with Alzheimer's dementia often present with a variety of cognitive complaints (frequently memory related). In Alzheimer's disease there is a loss of cortical neurons and synapses which results in cortical atrophy. As a result the ventricles in patients with Alzheimer's often appear large, hence the term hydrocephalus ex vacuo. CSF pressure is typically normal in these cases.
Espino et al. discuss a diagnostic approach to the management of the confused elderly patient. They note that these patients are commonly diagnosed with delirium or dementia but that other diagnoses should be considered and that reversible causes include: thyroid dysfunction, vitamin deficiencies and normal-pressure hydrocephalus.
Howard et al. conducted a clinical trial to see if cholinesterase treatment has benefits for patients with moderate to severe Alzheimer's disease. They found that continued treatment with donepezil for 1 year had significant improvement in cognitive performance.
Figure A is a CT scan demonstrating hydrocephalus.
Answer 1: Blockage of the cerebral aqueduct would likely cause increased ICP accompanied by neurological signs (e.g. vomiting, ataxia, acute behavior changes).
Answer 3: While conditions like choroid villous hypertrophy and choroid plexus papilloma could cause hydrocephalus secondary to CSF overproduction, these conditions are rare and much less likely than cortical atrophy in a patient with clear signs of Alzheimer's.
Answer 4: In a patient who was healthy and then developed symptoms late in life, a congenital malformation causing hydrocephalus is extremely unlikely.
Answer 5: This patient has no signs of infection.
Espino DV, Jules-Bradley AC, Johnston CL, Mouton CP. Diagnostic approach to the confused elderly patient. Am Fam Physician. 1998 Mar 15;57(6):1358-66. Review. PubMed PMID: 9531917.
PMID:9531917 (Link to Abstract)
Howard R, McShane R, Lindesay J, Ritchie C, Baldwin A, Barber R, Burns A, Dening T, Findlay D, Holmes C, Hughes A, Jacoby R, Jones R, Jones R, McKeith I, Macharouthu A, O'Brien J, Passmore P, Sheehan B, Juszczak E, Katona C, Hills R, Knapp M, Ballard C, Brown R, Banerjee S, Onions C, Griffin M, Adams J, Gray R, Johnson T, Bentham P, Phillips P. Donepezil and memantine for moderate-to-severe Alzheimer's disease. N Engl J Med. 2012 Mar 8;366(10):893-903. doi: 10.1056/NEJMoa1106668. PubMed PMID: 2
PMID:22397651 (Link to Abstract)