Affective and Cognitive Symptoms in the Elderly: Review and Case Report of Co-Occurring Klein-Levin Syndrome and Cerebellar Cognitive Affective Syndrome.

Illnesses with both cognitive and affective symptoms are common in older adults and have a broad neuropsychiatric differential diagnosis. We present a case of a 66-year-old female with fluctuating affective symptoms on a background of chronic dysexecutive cognitive symptoms, posing an intriguing diagnostic challenge and ultimately considered to be probable Kleine-Levin Syndrome (KLS) and cerebellar cognitive affective syndrome (CCAS). To our knowledge, this is the first published instance of both diagnoses not only co-occurring, but having a contemporaneous onset. This is followed by an overview of common differential diagnoses for such presentations, and a detailed narrative review of the features of and KLS and CCAS, highlighting their possible intersection. To account for the manner in which CCAS may have precipitated KLS in this case, we discuss the possible impact of posterior cerebellum damage on thalamic, default mode network, and other otherwise undamaged cerebral areas' function, via the disruption of broader neuronal connectivity networks.