The NPA traits are N (sanguinity, or narcissism), P (perfectionism) and A (aggression).
Posted by ABenis on July 6, 2011, 12:33 pm
We have been speaking of “protection” from schizophrenia (SZ), as in the paper* by Monakhov et al., but what exactly does this mean in the context of the NPA model?
“Protection” from SZ arises when researchers find an allele that is less frequently found in the SZ group as compared to control subjects. In the NPA model, having both the N and A traits fully expressed is very low risk. Hence, we can make the statement:
Protection from SZ arises when there is an excess of NA and NPA dominant types in the control group as compared to the SZ group.
Note that the key issue is that there must be a substantial number of NA and NPA types in the general (control) population. A corollary of this statement is that in order for protection to be detected 1) in a sanguine area, the prevalence of the A trait must be moderate to high, and 2) in a non-sanguine area the prevalence of the N trait must nevertheless be substantial.
That, is in a highly sanguine area where trait A is very low, all SZ patients and controls will be N and NP types, and the N trait cannot possibly show up as protective. Conversely, in a non-sanguine area where the N trait is very low, all patients and controls will be A and PA types, and the A trait cannot possibly show up as protective.
So, in general, both traits must be present to some extent for a protective affect to be discerned.
Referring to our “habitancies” (Benis 1985, 2008), here is the percentage of (NA + NPA) dominant types in each habitancy:
Polymorphic (mixture) – 58 percent
Sublime (predominantly N) – 4
Punctilious (NP) – 8
Introspective (submissive) – 28
Demonstrative (NPA and NA) – 82
Corybantic (NA) – 82
Authoritarian (PA) – 24
Militant (A and PA) – 24
The above shows that, practically speaking, protection from SZ by the A trait is least likely to be detected in the Sublime and Puctilious habitancies, simply because of the small numbers of NA and NPA types that would appear in the control groups. Somewhat counterintuitively, the most likely habitancies for detection of protection would be the Demonstrative and Corybantic habitancies because of the very high numbers of NA and NPA types that would appear in the control groups. But the exact numbers regarding protection would depend on the genotypes of the SZ individuals in each habitancy.
Given the above, it is understandable why some studies will find "protection" and some will not.
*Reference: Monakhov M, Golimbet V, Abramova L, Kaleda V and Karpov V. Association study of three polymorphisms in the dopamine D2 receptor gene and schizophrenia in the Russian population, Schizophrenia Research 100 (2008) 302–307.
Posted by ABenis on July 6, 2011, 9:37 pm
With regard to “protection” from SZ, I did some calculations to see what one could expect for the various habitancies.
I assumed that the risk of SZ was 1% for all types, except NA and NPA dominant types where it was assumed to be zero.
I calculated and compared the frequency (per 100 individuals) of trait N between SZ and the general population (“controls”), and also the frequency of trait A between SZ and controls.
In the bottom panel is the difference (delta) in the traits N and A between SZ and controls. The magnitude of this difference is “protection” from SZ due to that trait. (Researchers would actually be testing for difference in genotypes and gene frequencies for statistical significance).
I also added the two deltas together. The “sum” is a measure of the total genetic (N+A) difference between the SZ group and controls.
SCHIZOPHRENIA & CONTROLS IN VARIOUS HABITANCIES: Number of individuals with trait N and A (per 100 individuals)
SCHIZOPHRENIA & CONTROLS IN VARIOUS HABITANCIES: Differences in trait N (red) and trait A (dark green)
Note that the largest deltas are seen in the Demonstrative and Corybantic habitancies, and the smallest in the Sublime and Punctilious habitancies. Note that delta N is nil in the Sublime and Punctilious habitancies, while delta A is nil in the Authoritarian and Militant habitancies. The Polymorphic habitancy is somewhere in between. In the Authoritarian and Militant habitancies the difference between SZ and controls is nevertheless sizeable enough to be detected in a delta N study, but not at all in a delta A study.
Note finally the low deltas in the Introspective habitancy compared to the Polymorphic habitancy. This is because we have assumed that submissive types with the A- trait also have the same 1% risk of SZ, with submissive types therefore appearing in both the SZ group and the control group.
Reference for calculations of NPA phenotypes on the basis of gene frequencies (Hardy-Weinberg approach):
Benis A.M. (1985, 2008). Toward Self and Sanity: on the genetic origins of the human character. Chapters 10, 11. Psychological Dimensions Press, New York.