Benign Prostatic Hyperplasia (BPH): This condition is very common in older men and can cause urinary symptoms such as weak stream, hesitancy, and straining to urinate due to the enlargement of the prostate gland.

Urinary Tract Infection (UTI): UTIs can cause changes in urination patterns, including a weak or interrupted stream, especially in older adults.
Overactive Bladder: This condition can lead to urinary urgency and frequency, and sometimes a weak stream due to the bladder muscle contracting too often.
Neurogenic Bladder: Conditions affecting the nerves that control the bladder can lead to problems with urination, including a weak stream.

Prostate Cancer: Although less common than BPH, prostate cancer can also cause urinary symptoms, including a weak stream. Early detection is crucial for effective treatment.
Urethral Stricture: A narrowing of the urethra can cause a weak or interrupted urine stream and is a condition that requires prompt medical attention.
Bladder Cancer: Similar to prostate cancer, bladder cancer can cause changes in urination, including a weak stream, and is critical to diagnose early.

Urethral Diverticulum: An outpouching of the urethra can cause urinary symptoms, including a weak stream, though it is less common.
Sphincter Dysfunction: Problems with the muscles that control the flow of urine can lead to a variety of urinary symptoms, including a weak stream.
Bladder Outlet Obstruction: Any condition that blocks the flow of urine from the bladder can cause a weak stream, though the causes can be varied and less common.