In the 1800’s, and well into the 20th century, many people believed that certain parts of the brain had specific control over particular functions, so that there might be, for example, a “music appreciation” part of the brain. What we now know instead is that performing brain functions requires brain circuits to be intact. Unfortunately however, when these circuits pass through physical parts of the brain that are damaged, they too becom damaged. As a result, the ability to perform the functions is impaired. But that is not the same as having particular parts of the brain given over to particular functions, like hobbies.

Hobbies require many circuits to work in unison. Like all complex functions, it particularly relies on an intact front part of the brain. Different types of hobbies will require different skill sets, and different circuits. For example, hobbies that require manual dexterity Dexterity
Dexterity refers to one's ability to move hands and fingers.  For example, painters and musicians have above average dexterity., such as needlework, or wood-working, particularly involve circuits that go through the part of the brain known as the parietal lobes. These are commonly affected in mild Alzheimer’s disease. Even so, a typical pattern in mild Alzheimer’s disease is that these complex activities can still be carried out, and often to a high degree of skill, although it often takes longer to perform them. In addition, over time, people with early Alzheimer’s disease gradually lose interest. Commonly, they lose interest before they lose the skill to perform the hobbies.

Loss of interest in hobbies is often an early sign Sign
In medicine a sign is what a physician finds by examining a patient. For example, a patient with the symptom of pain might have signs of a fast heart rate, a pale face, a clammy touch and tenderness. of dementia, and sometimes is only seen in retrospect. It is common at any stage in life for interest in hobbies to be variable, and different people will have different patterns. Some people can only undertake hobbies when everything else is going well. Others throw themselves into hobbies as a means of relieving stress. But a decrease in either how well the hobby is done, or how interested the person is in doing it, are each common in mild dementia. It is this gradual decline in interest, and in skill, that families often see only in retrospect, after 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.). has been made.