In their effort to prevent the spread of infections, retirement homes have been forced to limit physical interaction between residents and the outside world and to drastically reduce their residents’ activities, decisions which are likely to increase loneliness in residents. To investigate this issue, we evaluated loneliness in patients with Alzheimer's disease (AD) living in retirement homes in France during the COVID-19 crisis. The study included 63 participants with mild AD. Participants were invited to complete the following statement “During the social distancing, I feel” with one of the three options: not at all alone, somewhat alone, or very alone. Most of the participants answered “somewhat alone”, suggesting a significant level of loneliness during the crisis. While it serves to prevent infections, social distancing in retirement homes is likely to result in significant loneliness in residents. Because loneliness may increase cognitive decline in AD, it to pressing to prepare social programs/activities that promote contact between residents of retirement homes and the outside world as soon as the confinement is lifted.