We are all Becoming Demented

For the first time since 1984 there is a new clinical diagnostic criteria for Alzheimer's disease dementia.  Published in April 19, 2011 in Alzheimer's & Dementia: The National Institute on Aging working with the Alzheimer's Association have expanded what we now consider  dementia.

While the previous guidelines only recognized one stage—Alzheimer’s dementia—the new guidelines propose that Alzheimer’s disease progresses on a continuum with three stages—an early, preclinical stage with no symptoms; a middle stage of mild cognitive impairment (MCI); and a final stage of Alzheimer’s dementia.  

These new guidelines forge a solid causal link. What was before just a probability of association is now seen as a causal progression from changes in the  brain that have no symptoms, to mild problems with thinking and memory and ending with dementia.

What made this possible is the introduction of new tests that can measure the health of the brain while the person is still alive. In the past, the only way to get a definitive prognosis of dementia was through an autopsy. Nowadays, especially with functional magnetic resonance imagery, the use of biomarkers makes it possible to measure changes in the brain before any symptoms appear, hence the new guidelines.

This ushers in a new era of fatalism. Unintentionally, these new guidelines are stoking the fear of dementia.  A MetLife Foundation study in 2010 reported that people over 55 dread getting Alzheimer’s more than any other disease--other then cancer. These new guidelines raises our sensitivity to subtler decline in thinking and memory. However it is important to stress that this linear connection is not as clear-cut as neuroscientists would have us admit.

MCI indicate difficulty with memory and thinking that are not normal but still allow the individual to  function independently. Many--but not all--people with MCI progress to Alzheimer’s dementia. However there are some important causes of MCI other than dementia--which the guidelines do not address--including medications, stroke or depression.

There are other inconsistencies in the logic of this causal path. As far back as thirty years ago M Marcel Mesulam with Northwestern University, reported 6 patients with progressive word-finding and naming difficulties that worsened over the years, but who did not develop a more generalized dementia.  Even if the connection between MCI and dementia is established, Mike Martin and his colleagues from Zurich, reported the results from their meta-analysis and concluded that cognitive interventions do lead to modest performance gains with older adults.

Even if the brain starts has the neuropathology it does not dictate the behavior. In the famous "Nuns Study" David Snowdon first reported this very strange anomaly. He found that a third of the nuns who behaved and acted free from dementia, were found to have the disease of Alzheimer’s during autopsy. Numerous studies have also found this lack of correlation between the disease and the behavior. More recently, Archana Balasubramanian with colleagues at UCLA reported that for 58 individuals, 90 years and older--who did not have any signs of dementia during three years prior to their death--at autopsy had evidence of the disease of dementia. All these studies erode the direct linear link between the disease and the behavior. There seems to be other mediating factors that the NIA guidelines need to address.

Mario Garrett, Ph.D., is a professor of gerontology at San Diego State University and can be reached at mariusgarrett@yahoo.com

Smell and Dementia

The sense of smell is accomplished through our olfactory system, which is an old system in our biological development. It is also one of the most evocative.

Smell acts as a portal to our emotions. It transports us directly to another time, another place and the only other medium that does this so quickly is the auditory sense--through music. But unlike music-- which can be written down and transferred in what Karl Popper calls World 3--smell is ephemeral.

Smell is somewhat undefined. Good, bad, sweet, acrid, then we loose track of translating the subtle smells into language. Smell has its own language and it cannot comfortably be translated into words.

Smell has power, it is evocative and nuanced so that a particular smell can immediately transport us to our first kiss, or the fear of high school, or your first child being born. Visceral and strong emotions which are hidden in the recesses of your mind. Never lost but subdued until dementia starts to erase them.

The olfactory system has a direct path to the brain. With humans, this system starts with the nose and ends a short distance away at the base of our brain. Olfactory receptors, with very thin fibers,  run  from the roof of the nasal cavity through perforations in the skull ending in the olfactory bulbs, which are a pair of swellings underneath the frontal lobes. It is the only sense that has such a direct physical connection to the brain. It is is also the first to be affected with the onset of dementia or Alzheimer’s. When the brain is affected by dementia, the area that deteriorates first is the area that is responsible for smell.

There is currently a patent, by researchers from Columbia University lead by Davangere Devanand, for a test using scents that include cheese, clove, fruit punch, leather, lemon, lilac, lime, menthol, orange, pineapple, smoke and strawberry. Using this test, the clinicians can predict that an individual who cannot recognize three of the ten scents are five times more likely to develop Alzheimer’s. It has also been found to predict Parkinson’s disease as well as certain types of schizophrenia and brain tumors.

Many people who lose their sense of smell also complain that they lose their sense of taste. Smell enhances the information we get from the mouth; salty, sweet, sour, and bitter tastes. Loss of taste might explain why weight loss is also an indication of dementia. It is not the weight loss on its own, but rather the loss of smell, which brings about the loss of appetite and consequently to diminished appetite.

There are some sixty seven medical conditions identified as possibly causing loss of smell--dementia being one of them. Some of these causes are temporary, such as colds, and nasal allergies such as hay fever.  It may also occur due to some medications and localized nasal polyps and tumors. Such factors reduces the odds of making the patent smell test a very reliable indicator in predicting dementia. But for individuals, it is important to notice changes in how well we can smell. So if you are having trouble with smell, check with your physician first to make sure that this is not a temporary condition.

Mario Garrett, Ph.D., is a professor of gerontology at San Diego State University and can be reached at mariusgarrett@yahoo.com