QUESTION: I'm 83 and have been told I have low blood pressure. One hears very little about low blood pressure. What are some of the causes, symptoms and treatments?

ANSWER: The phrase "low blood pressure" seems to imply that one's blood pressure is too low. Actually, blood pressure is never too low as long as there are no associated problems such as fainting or lightheadedness. When blood pressure is so low that symptoms do occur, the term "symptomatic hypotension" is used.Symptomatic hypotension is a problem for many older people. The regulation of blood pressure is a complex phenomenon, requiring the interaction of many different systems within the body. With aging, the body has more difficulty regulating blood pressure smoothly and rapidly. Stiffening of arteries and the reduction of cerebral blood flow may contribute to the problem. Under certain circumstances, blood pressure may decline to the point where serious symptoms such as dizziness and fainting occur.

Orthostatic hypotension is a fall in blood pressure causing symptoms which occur with a change in position. This often occurs when a person goes from a lying to a standing position. Symptoms also may occur with a change from lying to sitting or from sitting to standing. This problem can be due to normal aging processes, medication side effects or diseases such as Parkinson's disease, diabetes and alcoholism.

A variety of strategies can decrease symptoms of orthostatic hypotension. Chronic sufferers should rise slowly in the morning and sit on the side of the bed for a moment before standing. Similarly, rising slowly from a chair after prolonged sitting, and standing for a moment before walking can decrease the chance of a dangerous fall. Elevating the head of the bed slightly may help.

Hypotension often occurs or gets worse after meals. Recent studies indicate that about one-third of unmedicated elderly persons experience a reduction in blood pressure of greater than 20 points within one hour after a meal. Some doctors speculate that hypotension after meals may be an unsuspected cause of fainting and falls among the elderly. Patients experiencing such symptoms should avoid taking medications such as antihypertensives before meals.

If you believe you have symptoms of hypotension, discuss them with your physician. A careful review of the circumstances surrounding the fall in blood pressure is the key to correct diagnosis and management of this problem.

QUESTION: My husband and I are moving from our home of 40 years to Florida. We don't want to deal with the problems of owning a single-family dwelling and are thinking of buying a cooperative or condominium. However, we don't really understand the difference between the two. Can you help?

ANSWER: Many people think of cooperatives as 1960s-style group living, but co-ops have been popular in urban settings since 1945. Cooperatives offer many of the same tax benefits as single-family home ownership, with none of the headaches of maintaining a private home.

Cooperatives are corporations set up to operate the residential units. The owner of a cooperative unit owns shares in the building. The unit's location, size and layout are among the factors considered when the shares are allocated. Each owner usually has one vote, even though a resident with a larger unit may own more shares.

The purchaser of a cooperative apartment has a proprietary lease which outlines the owner's rights and responsibilities, as set forth in the corporation's bylaws and the house rules developed by the cooperative's board of directors. Cooperatives usually have rules concerning subletting and permanent guests. The board of directors typically reviews prospective co-op owners and must pass favorably on them before a unit can be sold. Because of these restrictions and regulations, many people believe cooperatives are harder to sell than condominiums.

In a condominium development, you hold title to your own unit, along with a portion of ownership in common areas and facilities. Each owner is required to carry insurance for fire, liability and other hazards. Normal maintenance expenses, such as for landscaping, are divided among the owners and billed at a fixed monthly rate. Unexpected, high-cost expenses, such as replacing a damaged roof, may result in a special assessment on all homeowners.

Like cooperatives, condominiums are generally managed by a board of directors elected by the tenants. Conditions, covenant restrictions and association bylaws govern life in the condominium development.

Before you buy either a condominium or a cooperative, consult a lawyer to be certain you understand the terms and conditions of the sale. Also, talk with residents of the co-op or condo development to find out what they think of the management company and the board of directors.

Send questions about growing older to On Aging, P.O. Box 84256, Los Angeles, Calif. 90073. Questions of general interest will be answered in the column; individual answers cannot be provided.