Chronic or recurring constipation, defined as fewer than three bowel movements per week over several months, is common among older people. It is not an inevitable consequence of aging, but results from a complex interaction of physiological changes, long-term medications, and shifts in daily lifestyle. Understanding these factors is crucial to recognizing why older adults are uniquely prone to this digestive issue.
Age-Related Physiological Changes in the Gut
The digestive tract undergoes alterations that slow the movement of stool. A key change is reduced colonic peristalsis, the coordinated muscle contractions that propel waste through the large intestine. When motility slows, the colon absorbs excessive water from the waste, resulting in harder, drier stools that are difficult to pass.
The sophisticated network of nerve cells controlling this process, the enteric nervous system, is also affected by age. There is a measurable loss of neurons in the myenteric plexus, the nerve layer coordinating muscle action in the gut wall. This neuronal loss makes the nerve signals that initiate and sustain peristalsis less effective.
The final stage, defecation, is compromised by the weakening of expulsion muscles. The abdominal wall and pelvic floor muscles naturally lose strength and coordination over time. This can lead to defecatory disorders where muscles cannot relax or contract properly, resulting in a sensation of incomplete evacuation.
The Influence of Medications and Underlying Health Conditions
Medications
Long-term treatments are a significant contributor to recurring constipation. Many older people manage multiple chronic conditions (polypharmacy), and numerous common drug classes list constipation as a side effect. Opioid pain relievers, often prescribed for chronic pain, reduce motility and increase water absorption by binding to receptors in the gut.
Other medications affect the nervous system or gut musculature. Anticholinergic drugs, found in medications for urinary incontinence, allergies, and certain antidepressants, block the chemical signals needed for normal gut muscle contraction. Calcium channel blockers, used to manage high blood pressure, relax the muscle tissue in the bowel wall, further slowing transit speed.
Underlying Health Conditions
Systemic diseases common in later life can also impair neurological control of the gut. Parkinson’s disease frequently causes severe constipation, sometimes predating motor symptoms, due to nerve damage affecting the autonomic nervous system. Similarly, diabetes can lead to autonomic neuropathy, where nerve damage to the gut wall reduces motility. Hypothyroidism slows the body’s entire metabolism, which is reflected in a generalized slowing of gastrointestinal movement.
Lifestyle and Mobility Factors
Behavioral and environmental factors often compound the physiological and medical challenges. Inadequate fluid intake is common because the aging process dulls the sensation of thirst. When dehydration occurs, the colon attempts to conserve fluid by drawing more water from the stool, causing it to become harder and more difficult to pass.
Reduced physical activity and immobility also slow the digestive process. Movement stimulates intestinal muscles, and a sedentary lifestyle or prolonged bed rest significantly decreases colonic peristalsis, contributing to slow-transit constipation. Immobility is a major risk factor for complications like fecal impaction.
Older people may intentionally ignore the urge to defecate due to mobility limitations or lack of privacy. Repeated suppression of the “defecation call” leads to rectal hyposensitivity, where the rectum becomes less sensitive to the presence of stool. The delayed response causes the stool to remain longer, becoming drier and firmer, which perpetuates chronic fecal retention.
When Constipation Becomes a Serious Concern
While chronic constipation is common, certain accompanying symptoms necessitate immediate medical consultation.
- Sudden, unexplained changes in bowel habits that persist for several weeks.
- The presence of blood in the stool (bright red or black/tarry).
- Unexplained weight loss, which may signal a serious digestive condition.
- Severe abdominal pain, distension, or vomiting alongside the inability to pass stool or gas, which can indicate a bowel obstruction.
Chronic, untreated constipation can lead to fecal impaction, where a mass of hardened stool becomes lodged in the rectum. This sometimes causes the paradoxical symptom of watery diarrhea leaking around the blockage.