A new study, published in the journal Biological Psychiatry, suggests that abnormal cholesterol levels can cause depression in the elderly.

Scientists evaluated a large population of elderly men and women aged 65 and older over a seven year follow-up period, assessing them for symptoms of depression and measuring their lipid levels.

They found that, in women, depression was associated with low levels of the "good" form of cholesterol, high density lipoprotein (HDL).

In contrast, the men who were at a greater risk of depression had low levels of the "bad" form of cholesterol, low density lipoprotein (LDL).

Researchers say that although low LDL levels seemingly protect men from developing cardiovascular diseases or strokes, their study suggests that it increases their mental health risk.

"Our results suggest that clinical management of abnormal lipid levels may reduce depression in the elderly, but different treatment will be required according to sex," wrote the study’s lead author, Marie-Laure Ancelin, Ph.D.

Eating a healthy diet and getting regular exercise are often considered key to keeping cholesterol in check. Among the herbs and nutritional supplements believed to help lower cholesterol are fish oil, flaxseed, garlic, blond psyllium, guggulipid extract, green tea extract and beta sitosterol.