Jeremy Brett was born Peter Jeremy William Huggins at Berkswell Grange in Berkswell, then in Warwickshire. His birthdate was actually on 3 November 1933 but it has also been stated as December 1933 or 1935, according to many sources, although this was probably a later vanity claim to reduce his public age. He was the son of Lieutenant Colonel Henry William Huggins, DSO, MC, DL (1890-1965), an Army officer, and Elizabeth Edith Cadbury Butler (of the confectionery dynasty). He had three older brothers: John, Patrick and Michael.

On 24 May 1958 Brett married the actress Anna Massey (daughter of actor Raymond Massey). Their son, David Huggins, born in 1959, is a British cartoonist, illustrator and novelist. Brett and Massey divorced on 22 November 1962 after she claimed he left her for a man. From 1969 until 1976, Brett was in a romantic relationship with the actor Gary Bond, who died exactly one month after Brett. In the late 1970s, he was involved with actor Paul Shenar. In 1976, Brett married Joan Sullivan Wilson, who died of cancer in July 1985.  In the latter part of 1986, Brett exhibited wild mood swings that alarmed his family and friends, who persuaded him to seek diagnosis and treatment for manic depression, also known as bipolar disorder. Brett was prescribed lithium tablets to fight his manic depression. He suspected that he would never be cured, and would have to live with his condition, look for the signs of his disorder, and then deal with it. He wanted to return to work, to play Holmes again.  The first episode to be produced after his discharge was a two-hour adaptation of The Sign of Four in 1987. From then on the changes in Brett's appearance and behaviour slowly became more noticeable as the series developed. One of the side effects of the lithium tablets was fluid retention; he was putting on weight and retaining water. The drugs were also slowing him down. According to Edward Hardwicke, Brett smoked up to 60 cigarettes a day, which "didn't help his health." He also had heart troubles. His heart was twice the normal size; he would have difficulties breathing and would need an oxygen mask on the set. "But, darlings, the show must go on", was his only comment.  During the last decade of his life, Brett was treated in hospital several times for his mental illness, and his health and appearance visibly deteriorated by the time he completed the later episodes of the Sherlock Holmes series. During his last years, he discussed the illness candidly, encouraging people to recognise its symptoms and seek help.Answer this question using a quote from the following article:

When was he diagnosed?
1985.