Self-injurious behavior within the menstrual cycle of women with mental retardation

There are no reports of an association between the menstrual cycle and self-injurious behavior (SIB) in the mentally retarded population. However, the endogenous opiate system has been implicated in both menstrual cycling and SIB. Catamenial and behavioral records of 9 women with mental retardation who exhibited SIB were analyzed for 6 months to determine the association between phases of the menstrual cycle and rates of SIB. Menstrual cycles were divided into four phases: (a) menses and early follicular phase, (b) late follicular phase, (c) early luteal phase, and (d) late luteal or premenstrual phase. Analysis showed that the highest frequency of SIB occurred in the first two phases: 43.5% during early follicular phase and 47.3% in the late follicular phase. Pairwise t and binomial expansion tests confirmed that SIB was cyclic across the menstrual cycle with Phase 1 > Phase 3, Phase 1 > Phase 4, Phase 2 > Phase 3, and Phase 2 > Phase 4. Seven of the 9 women were cyclers and manifested identical phase/SIB relations. The cyclical character of SIB may relate to changing peripheral and central endorphin and pain threshold during the cycle.