*Cognition Disorders/mo [Mortality]
        Mitchell, S. L., Kiely, D. K., Lipsitz, L. A. 1997. The risk factors and impact on survival of feeding tube placement in nursing home residents with severe cognitive impairment.. Archives of Internal Medicine.  157 (3) 327-32.  
          Perls, T. T., Morris, J. N., Ooi, W. L., Lipsitz, L. A. 1993. The relationship between age, gender and cognitive performance in the very old: the effect of selective survival. Journal of the American Geriatrics Society.  41 (11) 1193-201.