Research revealed that the most frequently reported symptom of LLPDD was depression; therefore, work group members felt it should top the list of symptoms for diagnosing PMDD (Severino, 1996).
While the categories of LLPDD and PMDD have been identified as advances in the provision of "operationally defined diagnostic criteria for PMS" (Freeman & Sondheimer, 2003, p.
Olasov & Jackson (1987) reported a general inability to find cyclical changes in affect associated with the menstrual cycle and Schnurr, Hurt and Stout (1994) found no significant psychological differences between women with and without LLPDD. Much of the psychological research done on women with premenstrual symptoms is correlational, thereby making it impossible to determine whether or not the psychological symptoms are causes or consequences of the menstrual cycle-related changes.
xxiii) for DSM-IV diagnostic categories, some authors have been critical of the DSM process (Caplan, 1991) and, according to Caplan (2004), even the DSM's own subcommittee on LLPDD concluded that "(1) very little research supported the existence of a premenstrual illness [that could be separated from the physical signs associated with PMS]; and (2) the most relevant research was preliminary and methodologically flawed" (Caplan, 2004, p.