viruses Herpes simplex virus (HSV) has been found in more than 70% of those aged over 50. HSV persists in the peripheral nervous system and can be triggered by stress, illness or fatigue. High proportions of viral-associated proteins in amyloid plaques or neurofibrillary tangles (NFTs) confirm the involvement of HSV-1 in Alzheimer's disease pathology. NFTs are known as the primary marker of Alzheimer's disease. HSV-1 produces the main components of NFTs. Diet Diet is seen to be a modifiable risk factor for the development of dementia. Thiamine deficiency is identified to increase the risk of Alzheimer's disease in adults. The role of thiamine in brain physiology is unique and essential for the normal cognitive function of older people. Many dietary choices of the elderly population, including the higher intake of gluten-free products, compromise the intake of thiamine as these products are not fortified with thiamine. The Mediterranean and DASH diets are both associated with less cognitive decline. A different approach has been to incorporate elements of both of these diets into one known as the MIND diet. These diets are generally low in saturated fats while providing a good source of carbohydrates, mainly those that help stabilize blood sugar and insulin levels. Raised blood sugar levels over a long time, can damage nerves and cause memory problems if they are not managed. Nutritional factors associated with the proposed diets for reducing dementia risk include unsaturated fatty acids, vitamin E, vitamin C, flavonoids, vitamin B, and vitamin D. The MIND diet may be more protective but further studies are needed. The Mediterranean diet seems to be more protective against Alzheimer's than DASH but there are no consistent findings against dementia in general. The role of olive oil needs further study as it may be one of the most important components in reducing the risk of cognitive decline and dementia. In those with celiac disease or non-celiac gluten sensitivity, a strict gluten-free diet may relieve the symptoms given a mild cognitive impairment. Once dementia is advanced no evidence suggests that a gluten-free diet is useful. Omega-3 fatty acid supplements do not appear to benefit or harm people with mild to moderate symptoms. However, there is good evidence that omega-3 incorporation into the diet is of benefit in treating depression, a common symptom, and potentially modifiable risk factor for dementia. Management There are limited options for treating dementia, with most approaches focused on