Ron Reagan reveals (My Father at 100) that his father was thrown from his horse six months after leaving office during July 1989. He sustained a closed head injury and needed neurosurgery to relieve the pressure in his brain. The surgeons discovered that he already had the neurological changes of Alzheimer’s disease. This raises two interesting issues about memory. First, there is a great deal of debate about whether President Reagan showed signs of Alzheimer’s disease while he was in office. Second, John McCain (aged 71) would have been the oldest elected president of the United States, if elected.

First, consider age. Although we don’t have a standard of too old to be president of the United States, there are a number of prejudices about age and competence. Should there be an age for mandatory retirement? Should there be an age for mandatory surrender of the privilege of driving? On the one hand, there are clear changes in efficiency of mental processes with age. Our thinking slows. Our reaction time slows. We have a more difficult time multitasking. On the other hand, we are very good at compensating for the changes in efficiency that accompanies aging. Also, knowledge and problem-solving experience improve with age as long as our mind stays “sharp.” More importantly, the factor most clear from research on cognitive aging is that there is great variability. This means there are some who function very well into their ninth decade and beyond and others who don’t. Therefore, there can be no arbitrary decision based on age alone.

Second, consider the chance of someone developing a progressive dementia such as Alzheimer’s disease. This unfolds over a period of at least a decade and the early signs are very difficult to differentiate from normal aging. The greatest risk factor for developing Alzheimer’s disease is age. Nearly 50% of those who life to be 85-90 will receive a diagnosis of Alzheimer’s disease. Again, age does not help to determine who may be capable and who is not. The converse of the statistic is that 50% of those 85-90 are cognitively able.

So how do we decide? It comes down to understanding what will happen early in the course of Alzheimer’s disease. The first sign will be subtle short-term memory loss. This will affect new learning as well as complex decision making. And in the very early stages, subtle memory loss cannot be determined by just listening to someone or administering a Mini-Mental State Exam. The only practical way is to provide a rigorous evaluation of short-term memory and cognitive skills. Ideally, I propose that the only way to assess whether a person is cognitively able to be president is to have them undergo a thorough memory evaluation. We raise the issues of physical health and can reassure ourselves by prudent evaluation. I recommend adding memory assessment to the equation with full disclosure. But why just pick on those who are in their 70s or just presidential candidates? Is it time for all candidates for public office undergo appropriate cognitive testing? Standard cognitive evaluations are being provided for players in the NFL. Why not do the same for those in public office? Furthermore, why not for the rest of us?