The sexual response cycle may be weakened at all stages by neurologic disease. Incentives lessen as intimacy between partners is altered and expectation of reward fades. Reduced sensation and mobility limit the effectiveness of stimulation. Attention to stimuli is interrupted by distractions about illness or sexual outcome or by difficulties in concentration. Appraisal of stimuli is negatively affected by depression, medication, or pain, thereby precluding subjective arousal. A sense of desire may not be triggered. Autonomic involvement limits physical arousal and orgasm. The outcome is unsatisfactory and lessens any future motivation. ANS, autonomic nervous system.