Q) I read your article about having a family history of Parkinson’s. I have a grandmother with Alzheimer’s. Am I likely to be diagnosed with it too?
A) It is completely understandable that a relative of anyone diagnosed with this horrendous disease would have at least a degree of apprehension about their future. Alzheimer’s is now the sixth leading cause of death (in the U.S.) with one out of three seniors having either this or some other form of dementia diagnosed before their death. Given our ageing population and longer life spans (at least in those staying away from drug’s capable of causing an overdose which have in the last two years contributed to the first drop in life span since the early 1960’s) the number of people being diagnosed is likely to continue to surge upwards.
In Alzheimer’s, it is believed that abnormal deposits of protein form hard plaques and tangles throughout the brain which ultimately build up to the point that they can interrupt the communication between neurons which are the “messengers” of the brain. Eventually, these neurons die and this continues to such an extent that eventually parts of your brain actually shrink. The damage appears to start long before (perhaps as much as a decade) symptoms appear but at some point in time memory and thinking skills begin to progressively deteriorate. There is no cure for Alzheimer’s and our best medications, while safe, work only modestly at best.
The good news amidst all of this doom and gloom is that the vast majority of cases of Alzheimer’s (more than 99 in 100) are not inherited. In fact, having a grandparent or parent diagnosed with Alzheimer’s in their 70’s or 80’s does not change your risk relative to the rest of the population even one iota. The same holds true for the second most common type of dementia. Like Alzheimer’s, most cases of vascular dementia are not due to gene defects and are therefore not likely to be passed down from generation to generation. The caveat to this is that the underlying health issues that can cause this form of dementia (such as high blood pressure or diabetes) may be passed on and it is thus even more critical than usual to control these diseases in order not to repeat an unfortunate family history.
For front-temporal dementia, a relatively rare diagnosis compared to the previous two, there is a much stronger inheritance pattern. 40% of those who develop this condition will have at least one close relative diagnosed with some form of dementia. The news is somewhat worse in the case of Huntington’s disease and Familial Prion disease which have a 50/50 chance of being passed on (because they are caused by a single faulty dominant gene) and a little better in Lewy body dementia in which 10% of cases appear to be tied to genetics.
Getting back to Alzheimer’s, there is one form of it that is more likely to be passed along to family members. In those who are diagnosed before the age of 60 (which is only about 3% of all Alzheimer’s cases), the disease is far more likely to have been caused by a mutated gene and therefore more likely to be inherited. The earlier a person develops Alzheimer’s, the greater the chance of inheritance. However, even in the extremely rare case in which a person is diagnosed in their 30’s, the odds of having a first degree relative diagnosed with it is only somewhat higher than one in 10.
This all begs the question, if genes appear to play such a small role in acquiring the disease, why do so many millions of people have it? Perhaps the best way to answer this question is to look at who is most likely to be diagnosed with it and draw conclusions from that. The number one risk factor is age. Given that this is a progressive disorder, perhaps caused by a cumulative amount of damage, this makes sense. Essentially the longer we have been around to absorb these injuries, the greater the chance is of our brain reaching a “tipping point” and succumbing to this abnormal protein accumulation.
Alzheimer’s is also more likely in females. Most scientists believe this is mainly due to the fact that females live longer than males (see point one) but a 2010 study suggested that the female hormone estrogen, which declines at menopause, may have a protective effect which disappears as its levels plunge. Another risk factor for Alzheimer’s may be having a previous history of brain trauma, such as a concussion. There appears to be a link between the two and there is evidence that brain injuries do result in large amounts of the same protein (beta amyloid) found in Alzheimer’s being created (although it does not appear to clump into the plaques).
People with mild cognitive impairment also seem to be at a slightly increased risk of diagnosis. All of these risk factors are a little disheartening because there really is not much you can do to control or lessen them. But there are a few risk factors that you can actively manage. The first is related to lifestyle and a healthy heart. Older adults with coronary artery disease or peripheral artery disease do seem to have higher risk for both Alzheimer’s and other forms of dementia. However, a healthy diet (check out the MIND diet which has been linked to a 19% reduced risk of being diagnosed with a dementia), exercising regularly, quitting smoking and controlling your blood pressure and sugars are good for your heart and subsequently for your brain. Other research seems to indicate that quality sleep may also be an important preventative step.
Lastly, a lifetime of learning not only seems to be associated with higher happiness scores but also fewer beta amyloid deposits. This was true of learning throughout one’s life, but the case is particularly strong for the efforts made in the early and middle stages. This could be in the form of a formal education but could also encompass many other mentally challenging activities such as learning a new language or a musical instrument.
In the end, much like Parkinson’s, a diagnosis of Alzheimer’s in the family is not a reason to wreck your life with misplaced worry about your future cognitive health. It should serve however as a firm reminder that there are steps that all of us could take that have been proven to help prevent these tragic outcomes from occurring as often as they do.
