Alzheimer’s on the nose

Loss of mental faculties is one of the scariest prospects of ageing. Among the causes of dementia, Alzheimer’s disease is the most common, causing around 70 per cent of cases. While there is no cure for Alzheimer’s, early diagnosis and intervention leads to the best outcomes. That makes it very interesting that a new study has shown that a simple thing like peanut butter could be a useful diagnostic test for early stage Alzheimer’s.

Alzheimer’s was first identified in 1907 by Dr Alois Alzheimer who reported the case of Auguste Deter, a middle-aged woman with dementia and specific changes in her brain. For the next 60 years Alzheimer’s disease was considered a rare condition that afflicted people under the age of 65. In the 1970s however, it became clear that senile dementia and Alzheimer’s disease were the same condition and that neither were a normal part of aging.

In Alzheimer’s there is a shrinking of the outer layer of the brain. This is the cortex, which is the region of the brain involved in memory, language and judgment. The “shrinking” of the brain is caused by the death of the brain cells. Additionally deposits are found outside the brain cells, which are known plaques and inside brain cells “neurofibrillary tangles” develop. These changes impair synapses so signals cannot pass between brain cells. Tangles kill brain cells by preventing the normal transport of food and energy around the brain cell. As a result a range of symptoms develop. In the beginning these symptoms could be subtle deficits in memory progressing to a real inability to function. The progress of Alzheimer’s will vary from person to person and diagnosis is difficult and made only after a range of assessments. While there is no single test for Alzheimer’s a new study has found that peanut butter could be a vital part of Alzheimer’s assessment.

In the study patients coming to an Alzheimer’s clinic for assessment also sat down with a physician who had a closed container with 14 grams (one tablespoon) of peanut butter. The patients closed their eyes and blocked one nostril. The researcher opened the peanut butter container and held a ruler next to the open nostril while the patient breathed normally. The peanut butter was moved along the ruler one centimetre at a time until the patient was able to detect the odour of the peanut butter. The distance from the nose was recorded and the experiment was then repeated with the other nostril. The diagnosis of the patient was not known until three weeks after the test.

It was found that patients in the early stages of Alzheimer’s showed a dramatic difference in detecting odour between the right and left nostril. In people with Alzheimer’s the left nostril did not detect the smell of the peanut butter until it was on average 10cm closer than the for the right nostril. In people with other types of dementia there was no difference between the left and right nostril. Among patients with mild cognitive impairment, which can signal early Alzheimer’s, around 40 per cent showed the left nostril being worse than the right at detecting the smell.

One of the first parts of the brain to lose function in Alzheimer’s is the front of the temporal lobe. This is involved in forming new memories but it also evolved from the system that detects smells.

The peanut butter test is not definitive for a diagnosis of Alzheimer’s but taken in context of other signs it could be an early indicator that might allow intervention as soon as possible for this troubling condition.