I do not think any NT spectrum should be devised.
I disagree, because If we are going to continue to use the terms 'low functioning' or 'high functioning' autistic then by the same token we need to understand what is meant by a 'low functioning' or 'high functioning' neurotypical to give the matter some perspective.
There is already a commonly used global assessment of functioning that can apply to everyone autistic or not autistic, that is part of the DSMIV diagnostic manual.
There are no set standards as to what differentiates high functioning from low functioning autistics other than an abscence of cognitive deficits, currently per diagnostic guidelines of Aspergers.
However, there are individuals with Aspergers that fall into the rock bottom scale of global assessment of functioning.
91 - 100 No symptoms. Superior functioning in a wide range of activities, life's problems never seem to get out of hand, is sought out by others because of his or her many positive qualities.
81 - 90 Absent or minimal symptoms (e.g., mild anxiety before an exam), good functioning in all areas, interested and involved in a wide range of activities, socially effective, generally satisfied with life, no more than everyday problems or concerns (e.g., an occasional argument with family members).
71 - 80 If symptoms are present, they are transient and expectable reactions to psychosocial stressors (e.g., difficulty concentrating after family argument); no more than slight impairment in social, occupational, or school functioning (e.g., temporarily falling behind in schoolwork).
61 - 70 Some mild symptoms (e.g., depressed mood and mild insomnia) OR some difficulty in social, occupational, or school functioning (e.g., occasional truancy, or theft within the household), but generally functioning pretty well, has some meaningful interpersonal relationships.
51 - 60 Moderate symptoms (e.g., flat affect and circumstantial speech, occasional panic attacks) OR moderate difficulty in social, occupational, or school functioning (e.g., few friends, conflicts with peers or co-workers).
41 - 50 Serious symptoms (e.g., suicidal ideation, severe obsessional rituals, frequent shoplifting) OR any serious impairment in social, occupational, or school functioning (e.g., no friends, unable to keep a job).
31 - 40 Some impairment in reality testing or communication (e.g., speech is at times illogical, obscure, or irrelevant) OR major impairment in several areas, such as work or school, family relations, judgment, thinking, or mood (e.g., depressed man avoids friends, neglects family, and is unable to work; child frequently beats up younger children, is defiant at home, and is failing at school).
21 - 30 Behavior is considerably influenced by delusions or hallucinations OR serious impairment, in communication or judgment (e.g., sometimes incoherent, acts grossly inappropriately, suicidal preoccupation) OR inability to function in almost all areas (e.g., stays in bed all day, no job, home, or friends)
11 - 20 Some danger of hurting self or others (e.g., suicide attempts without clear expectation of death; frequently violent; manic excitement) OR occasionally fails to maintain minimal personal hygiene (e.g., smears feces) OR gross impairment in communication (e.g., largely incoherent or mute).
1 - 10 Persistent danger of severely hurting self or others (e.g., recurrent violence) OR persistent inability to maintain minimal personal hygiene OR serious suicidal act with clear expectation of death.
A person can have an IQ of 160, be a billionaire, and end up in the lowest scale of functioning, at some point and time in their life. A person with an 80 IQ that makes minimum wage can be in the highest of levels of functioning per this scale. Life is capricious; there is no guarantee of functioning on a day to day basis regardless of apparent advantage or adaptation that may be perceived by external appearances.
In diagnoses of ASD per the DSM5, everyone with an ASD diagnosis will have significant limits and impairments in everyday life functioning. There will no longer likely be high functioning autism as it relates to the global assessment of functioning. It would be almost impossible to score higher than 70 on the GAF, and be diagnosed with Autism Spectrum Disorder per the DSM5.
The minimal severity level of 1 would likely put someone no higher than a 70 scale of functioning, level 2 would likely put someone no higher than 60 on the scale of functioning, and level 3 would likely put someone at below 50 on the scale of functioning.
For perspective the Billionaire with an IQ of 160 can be at a scale of 0 to 10, depending on the individual and life circumstances.
These global assessments of functioning are used, in part, to determine whether or not someone meets the standards to gain financial assistance in the US, for subsistence puposes.
There is the common misperception that individuals with Aspergers are automatically high functioning because they have no intellectual deficits and cannot score lower than 70 on an IQ test, and technically be diagnosed with the disorder. There are many individuals diagnosed with Aspergers that are not assessed higher than 70 on the gaf assessment regardess of IQ. In everyday life the GAF is a more important measure of functioning than IQ.
I've never been higher than 80 on the GAF scale, because I've always had a narrow range of interests in life. However, I've been described by others per the description above, in the 90 to 100 range, to my surprise at different times in my life.
The GAF functioning scale is subjective; from my viewpoint I went fairly long stretches of time in my life, where I could not imagine being any happier. In my opinion that's a hundred in the grandscheme of human functioning experience. But, technically from the perspective of cultural norms per friends and wide ranges of interest, I was no greater than 80, in the GAF scale.
I likely would have been diagnosed with classic autism as a child, if they diagnosed children back in those days with verbal delays. However, there is no way I could have been diagnosed in 23 years of my adult life, because I never had a reason to visit a doctor.
Interesting too that if Abraham Lincoln had been assessed with the GAF, he would have likely scored in the 50 to 60 range, but that was his normal in life. An adversity that he lived with and was able to overcome with the highest of achievements among cultural norms.
Not suggesting he had an ASD, but there are those that suggest he had psychopathic traits, per inherent biology, in his lifelong flat affect; which he related as chronic depression.
A diagnosis for an ASD, is only necessary when one has problems meeting the demands of everyday life functioning. One person's difficulties/adversities that end in failure, may end in the highest of achievements in similar circumstances for another individual.
What is high or low functioning in anyone, is dependent on what one considers important in life functioning; and the external cover of an individual is never a sure indicator of what lies underneath that cover, per what may be subjectively determined as high functioning.
The functioning criteria is really only useful for determining support and therapy, per diagnostic guidelines, regardless if one is autistic or not autistic. It is hard to determine it for sure, from the outward appearance of others, so it is not always effective to try to label others as such through outward appearances.
There are threads that address GAF, among individuals that express themselves in extremely intelligent ways in online autistic communities; looking through some of them, it is rare that someone reports their functioning ability per the GAF scale as higher than 70, and most people with what is considered a high functioning form of Autism, Aspergers syndrome, report scores around the 50 range. That is social security disability territory for those fully assessed and determined as such.
This appears to be a problem with the DSM5, because failure to accommodate and adapt to social demands can occur much later than childhood for some individuals, when adaptations lose their effectiveness.
There are some adults with ASD spectrum disorders, diagnosed in adulthood, that already prove this to be a reality. At one point in time, they were able to adapt sufficiently, to never make anyone externally question their overall functioning ability in life, other than a bit of odd.
I'm not suggesting that the older folks diagnosed with ASD's are inherently more reslient to adapting to life, I think it is likley much harder to adapt today, given the level and variety of assault of stimulus in life than there was when I was growing up in a small town.
It's likely always been tough in large population centers. Research actually suggests this as the case for both individuals with Autism Spectrum Disorders and other disorders like Schizophrenia that grew up in large cities.
So, while there may not be significantly more people in the world with atypical neurologies, there be many more that have developed problems in functioning in everyday life, because it is more demanding for some than it was in the past. That moves well beyond the statistics of the 1 in 88, because that statistic is limited to 8 year olds, well before the full social demands of life may present a problem for adaptation.
Still waiting on studies that provide a full demographic of the issue. From my point of view, while some may improve with early intervention, others that do better early on, whom current studies don't even identify or measure, may have significant problems later on into adolscence, adulthood, or even later on in adulthood when greater social demands must be met.
Just the factor of a supportive family may make the difference where functioning may become an issue for some in different areas of the spectrum, across a lifespan. It's definitely a large part of where my personal feeling of a 100 GAF score came from, during the course of my lifetime. I can't credit complete independence for it.