We identify a temporal loss-of-function of TDP-43 starting with individuals characterized by differentially affected pools of neurons, some with evidence of cryptic splicing events and some with normal STMN- 2 splicing, who had not yet begun to develop symptoms of cognitive decline and ending with clinically manifesting individuals who had a complete loss of STMN-2 expression. Here, STMN2 is linked to Mental deterioration.