The sense of smell is closely connected to memories, which is why a pleasant scent can immediately transport your mind to another happy place or bring you comfort. But, what happens if your sense of smell begins to change? This doesn’t just mean you are missing out on comfort and good memories, it could signal health problems.

Some people begin to smell things that are not there (phantosmia), others may smell things differently or unpleasantly (parosmia). Still others may lose their sense of smell altogether (anosmia). Any of these changes, except when explainable by having a head cold, perhaps, could signal problems.

Donald A. Wilson, Ph.D., deputy director of the Emotional Brain Institute at the Nathan Kline Institute for Psychiatric Research and a professor at New York University School of Medicine, states, “Problems with smell are associated with many disorders and often show up very early in the disease progression.”

Here are five conditions that have changes in the sense of smell associated with their symptoms:

1. Alzheimer’s Disease

A study conducted at the University of Florida evaluated participants’ sense of smell in their left and right nostrils, and determined that those with less powerful sense of smell in the left nostril were more likely to develop early-onset Alzheimer’s. Ileana Showalter, M.D., stated, “Decreased sense of smell is one of the earliest signs of Alzheimer’s disease.” This degenerative brain disease may begin to attack the smell sensors in your brain first.

2. Parkinson’s Disease

The sense of smell requires that your nose and brain work together. Within your nose are olfactory sensory neurones, and when you smell something those neurones send messages to your brain to identify the scent. If you are having trouble smelling familiar smells, like car exhaust or delicious bacon frying, then this may indicate that there are changes happening within your brain. Like Alzheimer’s disease, Parkinson’s is degenerative, which makes sense when considering the loss of the sense of smell as an early sign.

3. Hypertension

Those with a diminished sense of smell may also have a diminished sense of taste. This can lead to overdoing it with the salt shaker while cooking. Too much salt can lead to hypertension. Alan R. Hirsch, M.D., a neurologist and psychiatrist who specializes in the treatment of smell and taste loss states, “People don’t realize that 90% of taste is smell. So when they say they can’t taste something, it’s really their sense of smell that’s off.”

4. Obesity and Diabetes

When you cannot smell or taste your food properly, you are more likely to overeat, according to Hirsch. Overeating leads to obesity, which is highly correlated with type 2 diabetes.

This information should not make you panic about looming health conditions, but it should help make you more aware of early signs of problems that might be related to your sense of smell. Be sure to not ignore changes in your health, and see your doctor soon if the problem does not resolve.