Mammal meat (pork, beef, and veal) are very unhealthy according to the findings of numerous studies.  Chicken and turkey are not as bad, but the skin should be avoided.  Fish and seafood do much better.  Becoming a vegetarian is a good idea, so long as you remember to get some of the vitamins and minerals found primary in animal products.

Fat: High Fat Diet Bad: Small study links AD to high fat diet according to healthscout.com. Study with transgenetic mice found linked to hypercholesterolemia. Neurobiol Dis 2000 Aug;7(4):321-331. Dietary cholesterol also accelerates accumulated of amyloid two fold. Ann N Y Acad Sci 2000 Apr;903:335-44. Low DHA a risk factor. Lipids 1999;34 Suppl:S245. F2-isoprostanes are prostaglandin-like compounds derived from free radical-catalysed peroxidation of arachidonic acid. Peroxidation of eicosapentaenoic acid produces F3-isoprostanes, whereas peroxidation of docosahexaenoic acid would give F4-isoprostanes. This study demonstrates the presence of esterified F4-isoprostanes in human brain and shows that levels are elevated in certain brain cortex regions in Alzheimer's disease. Our data with Alzheimer's disease suggest that analysis of F4-isoprostanes will provide new opportunities to study lipid peroxidation in the neurodegenerative diseases. J Neurochem 1999 Feb;72(2):734-40. F4-neuroprostanes could be detected in normal human cerebrospinal fluid and levels in patients with Alzheimer's disease (110 12 pg/ml) were significantly higher than age-matched controls (64 8 pg/ml) (p < 0.05). F4-neuroprostanes may provide a unique marker of oxidative injury to the brain and could potentially exert biological activity. Furthermore, the formation of F4-neuroprostane-containing aminophospholipids might adversely effect neuronal function as a result of alterations they induce in the biophysical properties of neuronal membranes. J Biol Chem 1998 May 29;273(22):13605-12

Fat: Animal Fat, Cholesterol Bad; Fish Good: Prospective Zutphen Elderly Study (n=476) and the Rotterdam Study (n=5,386). Rotterdam Study showed that high intakes associated with an increased risk of dementia after adjustments: total fat (RR=2.4 (95%CI: 1.1-5.2)), saturated fat (RR=1.9 (95%CI: 0.9-4.0)), and cholesterol (RR=1.7 (95%CI: 0.9-3.2)). A high fish consumption, an important source of n-3 PUFAs, reduced the risk of dementia (RR=0.4 (95%CI: 0.2-0.9)). In the Zutphen Elderly Study a high linoleic acid intake was associated with cognitive impairment (OR=1.8 (95%CI: 1.0-3.0)). A high fish consumption tended to be inversely associated with cognitive impairment and decline (RR=0.5, 95%CI: 0.2-1.2). J Nutr Health Aging 2000;4(4):202-207

Fat: Low in Saturated Fat/Cholesterol Helps: A study in the European J Clinical Nutrition found elderly individuals consuming a healthy diet were less likely to suffer dementia. 1,600 individuals who were 70 or older. food questionnaire and measure their mental function. nutrient intake was measured; each was ranked as having normal mental function or deficits that ranged from mild to moderate to severe. lower risk of cognitive decline for diet that contained a healthy balance of nutrients and was low in saturated fat and cholesterol. Compuserve 1/20/02

Fats, Cholesterol, Statins Not Related in Rotterdam Study: American Academy of Neurology 12/24/02, dietary intake of fat was not associated with an increased risk of dementia. For this study, more than 5,000 subjects from the Rotterdam Study, a large, population-based study examining risk factors for a variety of diseases among the elderly, were followed for an average of six years by researchers from Erasmus Medical Center in Rotterdam. Intake of total fat, saturated and trans fats and cholesterol was not associated with an increased risk of dementia. Additionally, intakes of specific fatty acids and/or cholesterol lowering medications were not associated with a reduced risk.

Fats: Saturated Bad: Rush Institute study found group eating most sat fat had double the risk of AD vs lowest intake. Omega-6 and monounsaturated fats were protective. NIA funded, Arch Neur 2/03

Meat, Mammal Meat Bad, Fruits & Veggies Good: Case Western University School of Medicine and University Hospitals of Cleveland, Ohio are now saying that a diet rich in fruits and veggies and low in red meat may actually prevent Alzheimer's. Compuserve 7/18/02

Meat May Increase Dementia: Small 7^th Day Adventist study of 272 found that vegans and vegetarians were less likely than "heavy" meat eaters to develop dementia. RR 2.18 and 2.99 when past meat consumption was taken into consideration. Giem, Neuroepidemiology ‘93;12:28

Meat Bad, Veggies Good: Rush-Presbyterian-St. Luke's Medical Center in Chicago, examined 815 people aged 65 and older over a four year period. 131 developed AD. People who consumed a lot of saturated fat, found in meat and diary, were 2.3 times more likely to develop symptoms than those whose diet was low in these fats. Conversely, people whose diet contained high levels of unsaturated fat were up to 80% less likely to develop Alzheimer's disease than those who consumed low levels of unsaturated fats. 2/18/03 BBC News & Arch Neurol