Are Different Personality Types More or Less Susceptible to Alzheimer's Disease?

An article in StudyFinds.org reported on some research at the University of Geneva, Switzerland on the relationship between personality and susceptibility to Alzheimer's disease.  The researchers claim to have found that stubborn and argumentative people are less likely to develop Alzheimer's disease.  My wife's question is, "Well, what happened to you?"  (Maybe she never really said that, but she'd be justified if she did.)

The research was reported in the journal Neurology of Aging, and involved 65 subjects, 65 years of age and older.  The research investigated whether there was a relationship between personality profiles and brain integrity in old age.  The hypothesis was that brain structure might be involved in personality, and characteristics of varying brain structures might influence the advent and progress of Alzheimer's disease.

For slicing and dicing personality types, the researchers turned to the Big 5 model.  (Nothing to do with the sporting goods chain.)  The Big 5 model has largely displaced the Myers-Briggs type indicators as a tool for understanding (or misunderstanding) personality distinctions.  The Big 5 personality traits are:

• Openness to experience (inventive/curious vs. consistent/cautious)
• Conscientiousness (efficient/organized vs. easy-going/careless)
• Extraversion (outgoing/energetic vs. solitary/reserved)
• Agreeableness (friendly/compassionate vs. challenging/detached)
• Neuroticism (sensitive/nervous vs. secure/confident)

The researchers measured the volumes of the parts of the brain known to be affected by Alzheimer's disease at the beginning of the study and after 54 months.  They conducted neuropsychological assessments at those times, but also at the 18-month mark.  Results were evaluated in the context of the personality traits displayed by the test subjects.

This is similar to the testing I underwent for the insulin trial we discussed in Beating the Dementia Monster.  In that case, my brain volumes were measured by MRI at the outset of the study and again at 18 months.  I had neuropsychological assessment quarterly for 18 months.

So what did the new study find?

• Lower agreeableness is associated with better preservation of limbic areas.  (Or could we call that higher disagreeableness?)  The limbic system includes the hippocampus and is critical to emotions and the formation of memories, among other things.

• Age-related hippocampal volume decrease was lower in subjects with higher openness.

• Personality impact on brain volume is independent of beta amyloid and presence of the APOE4 gene often associated with a higher risk of developing Alzheimer's disease.