The present invention generally relates to the treatment and/or prevention of Alzheimer's disease, other neurodegenerative diseases, and/or diseases characterized by the presence of certain metal ions, by using certain compositions including organosilicon compounds. A composition of the invention may be administered to a mammal, such as a human. In some cases, the composition may include a silanol, a silandiol, a silantriol, or a cyclic organosilane, and/or be able to form a silanol, a silandiol, or a silantriol upon exposure to physiological conditions such as are found in the blood, in the stomach and/or gastrointestinal tract, or in the brain or other organ. In certain cases, the organosilicon compound may be bound to a moiety able to be transported across the blood-brain barrier into the brain, for example, an amino acid, a peptide, a protein, a virus, etc. The organosilicon compound may also be labeled (e.g., fluorescently or radioactively) in certain instances. In some embodiments, the composition, or a portion thereof, may sequester aluminum, copper, iron or other ions, for example, by electrostatically binding to the ions. The composition may also include other functionalities such as amines, certain alkyl and/or aryl moieties (including substituted alkyls and/or aryls), or hydrophobic moieties, for example, to facilitate transport of the organosilicon compound through the blood-brain barrier.