another unused fiction scenario

Actually, aside from the fictional disease it strikes me as fairly plausible.

2305: Incident in very near future; terrorist dispersal of prion disease causes mass senility largest % adult cases result in total cognitive loss and subsequent premature death in all but a handful: other significant percentage suffer varying degrees of memory loss, impairment of short term and or long term memory formation, loss of language, loss of higher cognitive functions, cumulative impact creating a majority adult population ranging from high function, language-comprehending individuals lacking cognitive equipment to engage in undirected, independent or planned activity to permanently damaged individuals, totally lacking higher symbolic intelligence, living as animals as roaming solitary predators or violent and loosely organized packs. A higher percentage of children are able to regain some or most of their cognitive function because the major damage occurs prior to the completion of brain development. A small percentage of individuals both adult and child are unaffected by the disease due to a rare mutation or an artificial vaccination the origins and method of production for which is lost in the first and most chaotic century following the plague. Several hundred years after the plague begins a human population of several hundred million exists thinly spread over the globe, concentrated in a few dozen emergent societies built in the information-rich ruins of the world’s greatest cities: Tokyo, New York City, Mexico City, Bombay, Sao Paolo, Los Angeles, Shanghai, Lagos, Calcutta, and Buenos Aires. Warlords control all cities. The average life expectancy is thirty or fourty years, and early-onset senility is highly common in older adults. A small, young adult population in each cities have a disproportionately high impact on local politics due to their superior cognitive function: in some they are a ruling class while in others they are a despised and fiercely hunted heretical insurgency. Many but not all of the Warlords are secretly or openly of preplague normal functioning intellects. Many individuals are passing for a higher or lower function capabilities based on their local environments. All societies are segregated to some extent by castes based on broad functional groups. All societies must compete with animalistic human packs which steal food and kidnap females from human settlements. Some groups preserve a more or less accurate history of the events leading up to and subsequent to the plague (the latter much more fragmented due to the nature of postplague society) and a (progressively more idealized and divorced from reality) sense of the past history of the world as understood by preplague societies. In the current society the majority of preplague technology has ceased to function; technologies from the 16th to 18th centuries are being recreated. There were several small scale nuclear wars in the first two centuries postplague. Unknown agencies destroyed the majority of nuclear weapons and after the 3rd century postplague there are no known working nuclear weapons and this technology has been lost. Transcontinental flight is impossible, only subatmospheric rocketry has been achieved, and there is no functioning orbital equipment. Coal is the only fossil fuel in ready supply. The atmosphere is heavily polluted, most precipitation is acidic, and the weather is extrordanarily chaotic due to global warming, nuclear winter, and mass atmospheric pollution.

this is what is up with this.