Control of appetite is complex, and not well understood. A lot of brain chemicals Brain chemicals
Chemicals released by the neurons in the brain in order to communicate. are involved, and while classically appetite is disrupted later in Alzheimer's disease Alzheimer's disease
A neurological disease that affects memory and behaviour. It is characterized by beta-amyloid plaques and neurofibrillary tangles in the brain. There is no known cause but genetics and lifestyle are thought to play a role., it can also be seen even in mild Alzheimer's disease, or before a diagnosis Diagnosis
The process by which a physician determines what disease a patient has by studying the patient’s symptoms and medical history and by analyzing any tests performed (blood, urine, brain scans, etc.). is made. Of course, sometimes, a decreased appetite reflects in decreased sense of smell and taste, which is seen in some people a few years before Alzheimer's disease starts.

There are several theories about why weight loss occurs in Alzheimer's disease. Many people believe that it reflects a 'more active metabolism', but there is little evidence to suggest that this is the case. What seems more likely is that certain aspects of the inflammatory response that occurs in Alzheimer's disease release chemicals that break down muscle Muscle
Body tissue that contracts to produce movement or force. , as well as having some effect on fat stores. This might be one reason that tube feeding is often ineffective in Alzheimer's disease. In addition, the part of the brain known as the hypothalamus is important in appetite control, especially the brain chemical called leptin. Studies about leptin and associated chemicals that control the sense of having eaten enough are an active area of inquiry by scientists interested in Alzheimer's disease.

People who are depressed often have a disrupted appetite. It is therefore worth having the person you care for evaluated for depression Depression
A disorder where a person experiences a constant state of sadness and low mood which interferes with their daily activity..